Bongo Archives 2

This is where you can find responses to all the enquiries that nurse has received over the years here at the Bongo Clinic. We have broken the information down into categories.

Please select the category you require.

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Chassis Electrics

Q: Where are headlight and sidelight relays situated? (Adrian from Chiswick)

A: Open the bonnet and look on the passenger side above the wheel arch. Starting at the header tank and moving forwards the relays are in the following order. 1) Headlight 2) Side and tail light 3) Aircon Hi/Lo 4) Fog light (if present). The relays are different on post 03 Bongos.

Q: I bought a new window switch for my driver door off eBay. Although it is for a Mazda 323 the buyer said it would fit my vehicle. I have a 2001 V6 lowtop. (Toby from Pontypridd)

A: Although this will fit pre-99 Bongos, on the later editions the switch  is wired differently so that the driver switch operates the passenger door and vice-versa. If you know what you are doing it is possible to reverse the process.

Q: My interior flourescent light is flickering, so I need to change the bulb. Any clues how you get the plastic case off? (John from Woolwich)

A: Look carefully and you will see that the base has two prise points around the edge to help get the cover off. If it’s tight, give it a gentle squeeze.

Q: Is it possible to fit LED bulbs for the headlights? (Paul from Bodmin)

A: I’d avoid LED headlamp bulbs. The reflector isn’t designed for the light dispersal LEDS give.

Q: Can you advise me on the correct fitment for headlamp deflectors on a year 2000 (new shape) Bongo? (Dave from Reading)

A: (Thanks to Mark Woodhouse for supplying the answer). “I recently asked Travelspot about fitting Eurolites and they came back with the following images.”

Q: Where can I find the relay for the side lights? (Paul from Bristol)

A: It is located next to the headlight relay under the bonnet on the nearside inner wing.

Q: Can you tell me were the sensor/button thingy for rear interior light is?? It comes on when the door is first opened but then goes out when door is
fully open?? (Ange from Wrexham)

A: It’s in the rear door handle – squirt some WD40 around inside the back pane, that should sort it.

Q: What’s the easiest way of getting to the wires behind the dash? I seem to have a problem with my speedo wiring. (Simon from Launceston)

A: Drop the steering wheel to its lowest adjustment, undo the 4 screws around the fascia, lift it out, 4 more screws holding the clocks in, pull it out, dead easy!

Q: How do I install a leisure battery? (Wendy from Falmouth)

A: Glenn Morgan has written a full illustrated guide, and it can be found at

Q: My drivers side window won’t go down properly. It starts off slow and stops half way down. Any idea how to sort this?
(Shirley from Poole)

A: (Thanks to Richard Williams for this):- Sounds like a case of ‘grease me please’. There are some runners in the door that guide the window, below them is a ‘contraption’ for want of betters words, that pushed the beast up and pulls it down, this being fed from the motor. Being a window, water can get in to the works. Don’t delay though, a burned out motor can be expensive.

Q: Although my key still operates the driver’s door, the central locking mechanism ceased to have malfunctioned. I know about the relay behind the glovebox, but that seems to be in order. Is there anywhere else I should check? (Rob from Barry)

A: This is quite a common problem, and is probably a dodgy wire where the wiring goes across the driver’s side door hinge. Look for the large rubber grommity thing that takes the loom into the bodywork (cunningly concealed by the rubber conduit section).

Q: Where is the light switch that activates the small rear light when the back door is open? I had assumed there would be an obvious plunger type switch. I suspect mine has a dicky earth as it does not operate the light though the light is working independently. (Tom from Edinburgh)

A: You will find the contact to be a blue wire that is connected to the lock at the bottom of the door. It makes an earth contact with the chassis when closed. Trace the wire up into the top of the tailgate. It passes through a rubber grommet into the bulkhead of the bongo.There are three connectors in the panel void. One does the rear demister (the big wires). The other does rear brake light in spoiler and rear wiper. The other one with a 4 pin connector does the central locking ,rear light and door contact. Chances are if the light isnt working then there is a wire that has chafed within the grommet area. It’s just a matter of renewing the cables. Be aware that the colours change between the main loom and the tailgate, so you must do a continuity test to find them out.

Q: We need to replace the interior flourescent light, but we are unable to prize off the plastic cover. Any tips? (Stuart from Preston)

A: 1) Grab the plastic cover in a claw like grip at the rear of the unit and squeeze gently towards the centre of the light cover.
2) There are 2 clips here in the roof of the unit.
3) Now wiggle it around and pull it towards the rear of the vehicle.
4) Another clip will be exposed at the centre front of the unit.
5) Unit should now come off.

Q: Can anyone tell me the way to get at the side light bulb at the front? Do You release the whole light from under the screw/plate fitting on top by the grill? Or do you get at it from the headlight cluster? (Smudge from Melksham)

A: This is how to do it on pre-99 vehicles. Slacken the screw above the side light that goes through the black, plastic lug into the slam panel and then pull the sidelight/indicator cluster towards the front of the Bongo. It’s not necessary to remove the screw completely. Then, on the back of the cluster you’ll see the lampholders for the sidelight and indicator. Twist the relevant one about 30 degrees anti-clockwise to the unit and the holder should pop out. For later models you can access the bulbs from under the hood.

Q: The instrument lighting on my Freda has gone AWOL. I had the instrument panel off and confirmed that all the bulbs are ok, as is the fuse (all other items on fuse #22 are working fine). (Peter from Christchurch)

A: The dashboard illumination is on the same circuit as the tail-lights, controlled by fuse #8 of the second fusebox under the bonnet.

Q: Unless there is something wrong with my eyesight, it would appear that when I pull up at traffic lights and the engine is idling, the headlights go out. Or become very dim. And then they re-activate once I get going again. Is this normal for a Bongo? (Donald from North Shields)

A: Because the Japanese spend many hours in severe traffic jams, even worse than the ones to get in the Tyne Tunnel at Friday tea-time, some of them have a device fitted to save on battery power. Look for a black rocker switch on front bulkhead above right foot or shin area. Switch it the other way and the lights will stay on all the time.

Q: Can you tell me the colour of the wire on the alternator to connect my relay for my caravan battery? (John from County Down)

A: It’s the thin oily-coloured one! Connecting a relay might cause the ignition light to glow faintly and if this is aesthetically unpleasant (I don’t like it myself) then you can actuate the relay from the ignition feed to the radio. This is live when the ignition is switched on but the starter is not cranking the engine and therefore has the (dis)advantage of being able to connect the batteries when the engine is not running! The other alternative is to use a voltage-sensing relay such as the Smartcom but these have their disadvantages too, namely they can burn out if they are overloaded or arrive from the factory incorrectly set (which has happened to us recently).

Q: I want to fit a second battery to my bongo and have found that there is room under the bonnet on the nearside directly opposite to where the current battery is fitted. This area even appears to have the bolt holes in the same position to fit a battery tray. Is there anywhere that I might obtain a battery tray to fit? (Derek from non-membersville)

A: These are available through the club shop.

Q: I have had a kitchen fitted in the back of my Bongo and with it a compressor fridge with dual voltage 12/24 dc. When this is connected to the leisure battery alone it’s fine but when it’s all connected to the Bongo it cuts out. This I was told was because the Bongo’s charge voltage is 15v dc and therefore when the fridge is selected to operate on 12v dc it detects the higher voltage and switches automatically to 24v dc. The 15v charge is then not sufficient to run the fridge and obviously the fridge then is not working. 1. Is the 15v charge correct? 2. How can we overcome this problem and have you had this in the past? (Henry from Chepstow)

A: This will not be due to the charging voltage, which should never get as high as 15 volts except under fault conditions. The problem is probably due to the length / thickness of the cable used to connect to the vehicle battery. The fridge instruction booklet contains a diagram of length vs wire thickness but the best bet is probably to use a voltage-sensitive relay to charge the leisure battery when the engine is running and, if neccessary, incorporate a manual override switch to connect the leisure battery and vehicle battery when stationary (but beware of flattening the start battery!)

Q: Can you give me any tips on where ( in the electrical circuit) I would wire up my spot lights? Do I have to have them independant of the head/side
lights with their own switch on the dash?. (Les from the middle of Salisbury Plain)

A: There is a plug behind r/h of dash. It is already wired for spots, just plug in new switch (it has 4 wires to it ) If the switch is on they will come on
with side and headlights.

Q: Which fuse is used for the operation of radio/mirrors/lighting & aircon? (Various)

A: The one that is top right in the fuse box below the steering wheel.

Q:Bloody hell! When I reverse, the bloody thing beeps at me. When I leave my bloody keys in the bloody ignition, the same thing happens. Is there any way to turn the bloody thing off? (Pete from St Helens)

A: The buzzer is located on the right side in the drivers footwell, pull off the plastic trim on the lower door frame you will see two aluminium cased units one behind the other. On mine it is the front one, it’s easy to check just put the ignition on and gear select in reverse, you’ll soon hear which one, then pull the two electrical connectors off the unit. Peace at last! (Update from member Chris Hawley): Just wanted to mention that it is vital the plastic trim is refitted properly if you remove the ignition/reversing beeper. When you floor the accelerator the trim will trap it ‘on’ if it pops out!

Fact sheets on the following related subjects are available in the members-only area of the site. 

Bulbs (changing front & rear lamps)

Climate Control Illumination

Continental Headlights

Current Affairs (about the leisure battery)

Dashboard Bulbs

Electrics (beginers guide to leisure batteries and hook ups)

Fusebox (diagram of fuse locations)

Interior Lights

Rear Door Electrics

Rear Light Removal

Transformer (converting from 110v to 230v)

Washer Motor

Window Switch

Wiring Loom


Q: Do you have any suggestions as to the best product to use for removal of damp stains on our roof tent? (Roger from Needham Market)

A: You need to use a non-bleach based product, such as Thetfords or Blue Diamond awning cleaner.

Q: My Bongo is a classy vehicle, except for those awful “Auto Free Top” and “Full Time 4 WD” decals. I know I can use a hair drier to remove them, but how do I get rid of that horribly pungent glue that is left behind? (Traffic Cop from Norfolk)

A: Halfords sell a sticker remover chemical (AutoGlym Intensive Tar Remover). Or you can use perchloethylene (dry cleaning fluid). Finnigans Hammerite Thinners will do the job as well.

Q: Ever since I bought my Bongo last summer, I have endeavoured to keep it clean inside and out. To achieve this, each morning either myself or my wife arise at 5am, and armed with an old toothbrush, ensure that the last vestiges of yesterday’s suburban grime are removed from the Bongo before I go to work at the local language school where I teach. But the other morning, when it was my wife’s turn, a strange look came over her face and she began to tremble. I realised at once that I would either have to find a new wife, or perhaps a different method of cleaning my vehicle. So my question is, will it be safe to put my SGL through the car wash at the local Safeways? (Doug from Egham)

A: Some members have done this without incident, but others have reported damaged fairings, smashed rear mirrors, cracked wing mirrors and broken aerials. So I wouldn’t really advise it.

Q: I absent-mindedly tapped my bowl on the steering wheel and a burning shard of torched shag dropped on the seat, creating a hole about the size of a 50p piece. Do you have any advice? (Doug from Egham)

A: You are using the wrong type of tobacco. From the description you give, I deduce that you were smoking a rough mix, perhaps Dutch in origin. This has a tendency to “ball-up” causing a major fire hazard in campervans. I find that St Bruno is very good and gives a leaner smoke. Also, you tapped the bowl on the steering wheel. It is much safer, especially when the vehicle is in motion, to tap the bowl on the back of your shoe. If you want DIY products for upholstery repairs, then visit the Smart Repair Shop.

Fact sheets on the following related subjects are available in the members-only area of the site. 

 Headlight Refurbishment

Cooling, Heating, Aircon

Q: There was a bubbling noise from the header tank on my V6 whilst driving. No movement on temp gauge. I stopped, let it cool down, but no drop in coolant level. My low coolant alarm did not go off. Returned home, all OK, but next morning LCA went off at start-up, and the header tank was low. No sign of any water under the vehicle, and no moist hoses or pipes. How do I identify the source of the leak? (Claire from Buxton)

A: Pin-hole leaks in the system are very difficult to detect. The fine spray evaporates over a running engine, so it could be coming from anywhere in the system. One of the suspects is the waterpump gasket or seal, but the only real way of checking is an Ultra Violet (UV) dye test. Kits are available on eBay and elsewhere.

Q: I’m thinking of changing the 2 pin temprature sensor on my diesel Bongo as the fans are running all the time.  Will I need to drain, bleed and refill the coolant at the same time? (Colin from Darwen)

A: If you coolant level drops below the level in the header tank. But, as Rita has pointed out on the Forum, “…. you can change it when the engine is cold and no pressure in the system, dont remove the caps. Remove the old one and put your finger in the hole ,remove finger and fit the new sensor. If you haven’t tried you could remove wiring from old sensor and connect to new sensor before make sure that this is your problem.”

Q: In the worst case scenario, if a cylinder head on a diesel Bongo overheats and cracks, does it affect a particular cylinder? (Den from Llandudno)

A: If the head cracks, it is usually on cylinder number 2 or number 3. It usually cracks into the exhaust port area. A check you can do is take the van out to get it warmed up and then without switching it off lift the seats (or unbolt the drivers seat to gain access its quite easy to do) and see if you can see a plume of steam/venting in a torch light where its condensing in the cooler air.

Q: I have a diesel Bongo. My temperature gauge does not move above zero, even when the engine has warmed up. Should I be worried? (Ken from Bedford)

A: This means your thermostat is stuck open or it has been removed entirely. Unscrupulous dealers have been known to remove thermostats to hide potential overheating problems. Get it fixed sooner rather than later.

Q: Can you explain what the different fans are for? I understand that there are radiator fans, and a scavenger fan? What do they do? (Barry from Monmouth)

A: The Scavenger fan is the one situated directly in front of the engine pointing upwards, it pushes air through the engine bay. It mainly comes on when static and the normal airflow has stopped hence causing the engine bay itself to heat up. It is controlled by an air-input sensor. The engine cooling fans are the ones behind the radiator which draw air in to cool the radiators, they also come on when the air con is selected to ensure that the air con radiator receives sufficient cooling. They are controlled by a temperature sender unit that sits low down on the cylinder head.

Q: I had some welding work done on my bongo and the mechanic needed to remove some coolant hoses whilst the work was being carried out. How do I know if he has bled the system correctly? (Nigel from Worthing).

A: If the front and rear heaters are both showing good heat output then you will be fine, any air lock in the system usually stops coolant flow, this shows first in the heaters, then triggers the front fans.

Q: Most of the Bongo parts suppliers sell one type of cap that fits both the radiator and the expansion cap. But I note that the genuine Mazda parts have different part numbers. Can you enlighten me on this? (Mike from Taunton).

A: The caps are interchangeable and as long as they are rated at 1.1 bar, you should not have a problem. However, only the expansion tank cap has the large spring loaded pressure relief valve underneath. They are physically interchangeable but will not work correctly if the wrong way round.

Q: Can anyone tell me why, after bringing my 2.5td Bongo up to temp on a short run, the coolant wants to bubble and gurgle out if the reservoir when I unscrew the lid? The temp gauge sits at the usual place, just below half, and the aftermarket tenp sensor doesn’t sound. (Kev from Paisley)

A: The coolant level will naturally rise when hot and should not noticeably bubble when the cap is on. If you remove the cap it reduces the boiling point such that it will bubble up. As long as the cap is on and you are not losing any coolant from the overflow pipe then you shouldn’t have anything to worry about. If however, the level rises and and comes out the overflow under pressure, it suggests either a faulty seal on the cap or air is present in the system. This could be due to a hole in the pipework which is allowing coolant to escape / air to be drawn in, or combustion gases are getting into the cooling system either from a failed head gasket or a crack in the head. (Thanks to Haydn for this)

Q: My windscreen is all misted up and won’t clear. There doesn’t seem to be anything coming out of the vents. Any clues? (Doug from Hertford)

A: In the passenger/driver footwell there are mechanical linkages which control the vents (picture below). Check that nothing has become disconnected.

Q: My Bongo has suddenly overheated. The low coolant alarm never went off. I have had the whole system checked and can’t find any leaks. Help! (Mick from Limerick)

A: At the recent Bongo Bash there were a couple of instances of this. On both occassions it was found that the radiator cap was not up to specification. Please ensure that both your radiator cap and header tank cap are rated to 1.1 bar.

Q: I have a Low Coolant Alarm. When I start my Bongo in the morning it peeps at me for a few seconds and the red light comes on. Is this normal (Kim from Cumbria)

A: Yes, perfectly normal and nothing to worry about. It is telling you that it is still working! If it stays on for a prolonged period though do NOT fire up the engine as it has probably done its job correctly.

Q: It would be helpful if someone could explain to me how air in the coolant system leads to the coolant evaporating. There doesn’t appear to be any sign of a leak, but the header tank needs topping up.(Pricey from Newport)

A: Any leak in the system from a hose, water pump, rad leak, pipe, or anywhere else will discharge water when running, and let air in when cooling. The coolant will evaporate as soon as it hits the outside world so you will not notice it. The imported air gathers around the highest spots in the system, usually the front heater, or the cylinder head, and stops coolant flow. This causes a rapid temp increase inside the engine, similar to leaving an aluminium milk pan on a stove.

Q: I was driving home and noticed the temp guage had moved higher than the normal 11 o’clock position. I opened bonnet and I could see that there was a lot of water that had sprayed from the top of radiator. Is it OK to start the engine to see exactly where the leak is? (Ken from Guildford)

A: Absolutely NOT OK!! Get it recovered to a good garage and ask them to pressurise the system to 1 bar. Do this without running the engine at all. This will show any leaks without poss damage to the engine.

Q: I’ve got a weeping radiator. It’s the crimped seam between the plastic top radiator manifold and metallic radiator body, top left as you look at it from the front. I know I’ll have to get the whole thing renewed, but I’m a long way from home. Any idea as to whether I can reseal it as a temporary repair? (Ross from Bristol)

A: Yes, I’ve done a temporary repair in the past. Clean thoroughly with methanol to ensure a non greasy surface and then use epoxy. Check that the epoxy is rated for about 120C. I applied it with the rad hot but the expansion bottle cap loose to reduce the chance of seepage. As the engine cools, once you put the cap back on, suction occurs and some glue is sucked into the join. The heat also helps the epoxy set off faster. (Thanks to “Diplomat” for this advice.)

Q: My Bongo was laid up for the winter. Before starting it up, I checked the level in the header tank, and it seemed very low. But there was no evidence of any leakage. Any ideas? (Carl from Leigh)

A: It may be the water pump seal. And you may need ro replace your expansion cap. The Bongo rests at 1 pound negative pressure when cold, provided your expansion cap is good. If it’s not good it can be higher, the cap is not letting in as it should whilst cooling so it sucks in where it can, usually the weakest point is the water pump seal. This usually seals again when warm, thus no sign of leakage.

Q: My Bongo’s temperature gauge is always at zero, except when the engine is working really hard, when it flickers in to life. That’s not normal is it? (Joe from Wilmslow)

A: It’s a very real possibility that your thermostat has either been removed, or drilled through. One of the usual reasons for butchering the stat is that a dodgy garage doesn’t know how to bleed the system after having some work done on the cooling system. This then gives the appearance that the engine is running smotthly when it isn’t. It’s an old way of curing all ills. (Not).

Q: What size is the Aircon Belt on a 2 litre petrol Bongo? (Amanda from Doncaster)

A: It measures 13 x 1025 mm.

Q: I’m sure there used to be low-coolant alarms for sale in the Bongo Shop, but now I can’t find them. Are they still manufactured? (Toby from Sunderland)

A: We no longer stock them because it is cheaper to buy direct from the suppliers. You can contact Haydn on 01458 270230 or visit his website

Q: When starting up, it sounds like not all the cylinders are firing at the same time. I’m also getting white smoke from the exhaust, but there’s no sign of overheating. Any ideas? (Andy from Brighton)

A: When a head gasket fails sometimes they dont go completely. You may have a little bit of pressure leakage between the layers of the gasket or a micro crack behind the injector shrouds in the head. That is OK (ish) most of the time but when it parks up for a little while with no combustion pressure from the cylinders a little bit of water leaks back into the cylinders and you get smoke on start up. You need to get it to someone that knows what they are doing, it needs a pressure test and a combustion gas block test, this will likely confirm head/headgasket problems. (Thanks to Paul at LPG Imports for this).

Q: I know they both have WL-T 2.5 diesel engines, but will a Ranger cylinder head fit a Bongo? (Tim from Dublin)

A: It will fit OK, until you have to air bleed its coolant system. The Bongo head has a triple spigot coolant outlet fitted top front, with the middle spigot added for connection of an air bleed hose. The Ranger head doesn’t have this, although you can tee off the pipe and fit a bleed pipe, but it’s a bit of a faff.

Q: Apart from price, what is the difference between a genuine Mazda thermostat, and a “pattern” thermostat such as that manufactured by Blueprint? (Tracy from Liverpool)

A: Both ‘stats perform exactly the same way. Where they differ is that the Mazda stat has an extra seal on the stem which prevents loss of wax at the extreme upper end of the temperature range. When wax is lost (and it doesn’t take much of a loss for this to happen) the ‘stat becomes ‘lazy’ – ie: it takes a higher temperature for it to respond. Also, at the top end, it may not fully close the bypass, again due to the wax loss.But this will only happen if the ‘stat has experienced very high temperatures. (Thanks to Steve Widdowson).

Q: I keep an eye on the coolant level in my header tank, and have noticed that I am losing about a cupful of coolant a month. I then top up with a 50-50 antifreeze mix, but I’m getting a bit worried. Surely I shouldn’t be losing any coolant at all? There’s no tell-tale signs anywhere……(Mark from Spalding).

A: Over time the rubber pipes can harden and the retaining clips are unable to apply the correct preassure and don’t seal properly so allowing a small amount of coolant to weep whilst the system is cold. Within a very short time the pipes warm up and reseal and the small amount of coolant that has leaked is given off as steam hence disgusing the problem area. This is more likely to occur during cold weather.

Q: I have recently changed the coolant in my Bongo. I followed the instructions on bleeding the system correctly, and have fitted a new thermostat (genuine Mazda item). Yet the main engine fans keep coming on, the bottom hose is very cold, and there is movement on the temp gauge. I’m thinking of replacing the waterpump, but is there anything else that might cause the fans to come on? (Adam from Padstow).

A: (Thanks to Ady & Steve & others for this): One thing you might want to check is the Engine Temperature Sensor. If it is defective, it may be sending a wrong message to the ECU, which means the fans will come on. If it needs replacing make sure you fit the genuine Mazda item; there are some cheap & nasty substitutes out there. The Mazda sensor (mb59318840a) costs about £40.

Q: I have heard that there is a product on the market called “Steel Seal”, which claims to be a permanant fix for cracked cylinder heads. At £30, it sounds too good to be true! Have you received any feedback about this sealant? (Naz from Leicester)

A: The manufacturers of Steel Seal, which should not be confused with K-Seal (which provides a temporary fix only) certainly make some bold claims. And one of the Bongonauts on the Bongo Forum (see here) has used it without incident. But there again we have had a report of someone buying a Bongo, driving it 30 miles, overheating problem, and upon investigation found the cylinder head full of gunk. We will keep the situation under review.

Q: The bottom bearing on my motor has seized and worn a hole right through the motor casing. I’ve packed it with grease and it spins more freely now but I don’t think it’ll last long. Do I have to buy a new one, or is there some kind of repair I can make? New heater motors cost a lot of money….. (Stuart from Bristol)

A: You should not need anew motor if this one still works. Get the motor out, take it apart and remove the bottom bush/bearing. You can do this by heatng it with a small blow torch and getting some pump pliers on it. Clean everything up, and use a plastic scourer on the armature shaft where it had seized. Apply some silicon grease to the bearing and the felt washer and put it back together. I also drilled a drain hole in the bottom of the bearing casing too. (Thanks to BongoMTBer for this)

Q: I am trying to get my Aircon system recharged, but the garage wants to know which type of oil goes in with the gas. (Colin from Kensington)

A: 14 ml of PAG46 will do the trick.

Q: I have recently had a replacement radiator fitted which I picked up cheap on eBay. Generally it works fine, with no overheating problems, but I have noticed that I am discharging some coolant on my drive overnight. It’s not the hoses. I suspect that it is because the new radiator, which came from a Ford Ranger, is configured differently. Can you confirm this? (Diane from Kent)

A: Ford Ranger radiators will fit OK, but you have to block off the top overflow pipe. This is simple enough to do. Two jubliee clips, a three or four inch length of hosepipe with the correct bore size and an appropriate bolt rammed up one end should do the job.

Q: Is there a quick test I can perform to find out if my cylinder head gasket is knackered? (Eddie from Bristol)

A: Ian from Chesterfield says; ” A quick test for failed head gasket is to remove the rad cap and start the engine up (you will need to remove the air cleaner ducting to get to it, 2 screws/bolts IIRC). Only do this when cold, start the engine and look for discolouration in the coolant (mucky brown) and for air bubbles. Either of these two symptoms would indicate that exhaust gas from the cylinders is entering the coolant and yes, a failed head gasket or even worse a cracked head. However, the only sure way to check is to get the system pressure tested.”

Q: My Bongo has developed an air con fan problem, it dosent seem to be the normal resistor or fan seized issues people have as the fan seems to work perfectly at all speeds. In fact the screen vents are getting full air speed form the fan & the windscreen clears fine. When I switch the mode button (I have the LED style Air Con controls) to blow air through the dash vents, nothing happens. (Stuart from Bristol)

A: (Thanks to Pastpants for this): See if the operating levers (in the driver’s footwell on the left hand side) are engaged. These are the levers that drive the flaps open /closed. They can slip out, and all you will get is a whriring from the motors.

Q: Is there a quick way of telling if my thermostat is working or not? (Tony from Portsmouth)

A: (Thanks to Ian Dunse for this):- A stat can fail in one of two ways:

  1. Stuck in open position – symptoms, engine coolant takes a long time to reach optimum operating temperature.
    2. Stuck in closed position – symptoms, engine coolant gets too hot, as coolant not allowed to flow, and overheats.

To check, remove stat and there should be a temp value stamped on it. Typically this might be 82 ie. 82 degrees centigrade. Place stat with a thermometer in a pan of water and bring to boil. If ok the stat will start to open at designated temp. If it doesn’t replace.

Q: I have been reading recently on the forum of a few problems of mechanically-sound Bongos being stricken by overheating problems, leading in one or two instances to cracked cylinder heads and even full engine replacements. Is there are any preventative action I can take to avoid this happenening to me? (Marjorie from Dore)

A: It’s difficult to prove exactly what was causing these recent problems, but one of the chief suspects is accumulated gunk in the radiator, which in turn leads to poor coolant circulation. So one of the precautions should be that you flush out the radiator at least every 2 years.

Q: Because I am a lazy arse, I forgot to flush out my radiator, and now my garage informs me that the radiator needs replacing. I have phoned Mazda, but they have quoted me a price that is far too high for my liking. Is there anywhere else I can source a radiator? (Marjorie from Dore)

A: There’s usually a few firms selling these on eBay for around £130 plus postage. Try Autojapspares on 0247-647-4848.

Q: My Bongo is suffering from an intermittant overheating and loss of coolant problem.The temperature gauge will suddenly swing over to hot and then return to normal and sometimes I can hear the coolant bubbling like a kettle in the engine. This also happens in the expansion tank although the radiator appears to remain full. The expansion tank cap,thermostat and water pump have been replaced and air locks have been investigated. There is no sign of oil in the coolant. Can you offer any advice please? (John from Nuneaton)

A: This sounds like a radiator problem to me. First, check that you are not losing pressure through your radiator cap. And secondly, get the radiator checked for blockages. In the worst case scenario it may need re-coring.

Q: I’ve got a 1995 Bongo with the basic horizontal slider control on the dashboard that directs the heater/blower air variously at the windscreen, feet, cabin etc. I’ve recently noticed that, regardless of the position of the slider, the direction of the blown air doesn’t change – it always just blows into the cabin. This is a pain because I can’t demist my windscreen and I can’t defrost my missus’ frozen feet! I’m guessing that a mechanical linkage somewhere behind the dash must have broken or separated. Can anyone suggest where I should start looking? (Tigger from Swansea)

A: On the passanger side if you remove the glove box you can clearly see one set of linkage There is another one under the centre console on the driver’s side. You can see where the cable coming from the control panel terminates and is hooked onto a white plastic swivelling lever type thing that switches the air flow. If it’s the windscreen vents that won’t work, it’s likely that this cable has come off – probably a carelessly placed size 11.

Q: So where is it? I’ve hunted all over the engine, looked under the seats etc, but I still can’t find the thermostat. (Nick from Leyland)

A: It’s easiest to access it from underneath. If you crawl under the Bongo, under the passenger side at the front you will see a black plastic cover with 8 bolts on it. It’s in here, hidden by the turbo. If you want to access it from above, then it can be found under the passenger seat, behind the alternator, looking down, under the exhaust manifold. Where the dipstick assembly bolts onto the block, the thermostat is in the unit on the side of the block, where the bottom rad and rad pipes etc are.

Q: These things seem to go with alarming frequency. So how can I find the fan speed resistor? (Mac from Fleetwood)

A: It sits on top of the air duct behind the aircon evaporator.

Q: I have a front & rear climate control system in my vehicle. One of the air conditioning options is entitled “Econ”. What does this do exactly? (Marianne from Sheffield)

A: Remember night storage heaters that used cheaper Economy 7 electricity overnight? Well, these units work on the same principle and only draw fresh air in to the system at night, when it is less expensive, chill it in a large tank that is suspended under the vehicle, and expels it in to your face during the day if the external temperature reaches 20 degrees celsius.

Q: I am just about to take my van in to have the Aircon sorthed out. What gas does it take and what quantity of gas should be used? (NBS of South Shields)

A: The gas is Safe Moern R134a and it should take 700g.

Q: I need to know the width and length of the air con belt for SGL3F please. I had a new one fitted a week ago and it broke. Mechanic thinks it was the wrong size! Can any one advise? I have a P reg 2.5 T diesel 2wd auto. (Chris from Havant)

A: It’s 13 x 1000 mm.

Q: When I put my air conditioning system on it smells like a sweaty sock left to marinate in tom cat urine. Does something need cleaning or replacing in there? (Wiskers from Norfolk)

A: This can be caused by one of 2 things. Either a tom cat has indeed been using your Bongo as a litter tray, or, more probably, it can be due to stagnant water, crud etc around the evaporator. Try a cheap quick-fix: get a can of Wynns air con freshener (try Halfords) and do what it says on the tin. Simple, quick and if it solves the problem, great. If it comes back, get someone to check the evaporator fins etc etc aren’t blocked.

Q: When we put the fan on in the back of the bongo the vent near the floor behind the drivers seat pumps out hot air which counteracts any benefit we get from the fans on the roof. Is this normal and is there anything we can do about it as we’re off to France soon and don’t want to roast? (Emma from Leicester)

A: The blow air system behind the driver seat is independent of both the aircon system, and the blow air system in the cab. It is activated when you flick the dash button labelled “Rear”. I have checked out mine this morning, and it blows out cool air. Not cold air as in air conditioning, but cool air. It gets this cool air from the engine cooling system. I would be inclined to turn this off when in a hot climate as the cool air being blown from the side vent will always appear warm compared the ice-chill of your aircon system blowing through the top vents. However, it may be possible that the rear blow air system is not working properly. If this is the case, it could be any number of things, including blocked inlets, resistor switches, motor unit etc.

Q: Does the radiator fan ( drivers side ) have a thermoswitch, and where is it located? Also how can you test it to check that its working OK? (John from Dorset)

A: The fans are operated by the ECU, acting on information from at least two sensors. You shouldn’t have a problem testing the operation of the fans in this hot weather! The big one in front of the engine will come on fairly quickly after you stop in traffic

Q: I’ve read somewhere that I should run my aircon system once a week to keep the pipes clear, even in the depths of winter. Is this true? (Eric from Hastings)

A: Member Craig Grady informs us that he had a problem with his aircon system and ” I called a local specialist who said if the coolant was too low a pressure switch shut the system down, for £60 inc vat they checked for leaks recharged the system and it’s as good as new. The Bongos aircon uses the safe moern gas (r134a) and it was just a case of the seal drying cos I didn’t use it over winter. Airkool of Hull reccommended running for at least 10 mins a week year round and a recharge every 3 years max as the coolant slowly absorbs water and loses efficency.”

Q: I switched my air conditioning on during the Easter break and although the little green light comes on the airconditioning is not working. I do not have the climateair conditioning system but the one that is set manually (temperature dial) and unfortunately this system is not referred to in my manual. The airconditioning has worked fine up until now and I have kept it running periodically during the winter period. I wonder if you have any idea what coule be wrong. (Alison from SE13)

A: Aircon systems are complicated beasts, and best left to specialists. But you might want to check the following before rushing to your local aircon clinic. These suggestions come from a Ford Ranger manual, which has a similar system.

1) Get the aircon belt checked. It might be slipping, or perished. If so, replace it .
2) Check all system hoses for leaks. Replace if appropriate (Hassop Mazda).
3) Clean the condenser with condensed air.
4) Check the refrigerant charge, and add refrigerant fluid if necessary.
5) Check it is not a fuse problem.

Q: My heater controls work fine on maximum (4) but are next to useless on other settings. (Colin from Norwich)

A: It sounds like you need a new fan speed resistor. which is situated near the fan engine. It looks a bit like an ignition coil only smaller, and there are 2 coils inside. If one of them has burnt out, your fan heater will only work at the fast speed. (Update from Sean George 05/05/04: I have recently had trouble with my fan speed resister, I diagnosed the fault myself and the resistors can be repaired as long as the card isn’t damaged. It was just a case of re-soldering the electrical pick up points on the side, these solder joints can become weak and brake due to vibration. You can seperate the card by grinding off the 2 rivets and replacing them with self tappers when putting them back together, much care is needed though and mine has worked fine for months.)

Q: My van keeps overheating. I assume it is the thermostat. But how can I tell? (Tom from Herts)

A: The quickest way to tell is to run the engine for a few minutes, shut it off, and then (carefully) use your hand to check the temperature of the upper radiator hose. If it’s cold, then the thermostat is probably stuck closed. But if it’s hot, it’s probably a cooling system problem.

Q: How do I get the rear heating controls to work? Nothing seems to happen….(Tony from Wakefield)

A: The rear air con only works when you switch it on from the front switches. I think the switch is labelled ‘REAR’. The front console controls the temperature for the rear as well as the front but you can control the fan speed and direction for overhead or from the side panel.

Q: My hot air heating system seems to have failed. Which is a bit of a problem as it’s minus 12 centigrade where I live. And that’s in July. What would you advise? (Jason from Derbyshire).

A: It sounds as if there is a air lock in the heater system, it is caused if the water has been drained for antifreeze or just gone down low. The two heater pipes (small hoses) should be the same temperature to touch. To bleed the heater system put the heater controls on the red position then you remove the heater hose at the heater (the highest one of the two). Block the heater to stop the water, toping up the hose pipe then refit hose to heater.

NB: Fact sheets on the following related subjects are available in the members-only area of the site. 



Coolant (Diesel)

Coolant Change (Petrol)

Coolant & Temperature Alarms

Coolant Alarm System


Fan Speed Resistor

Front Heater


Hoses for Petrol Bongos

Hose Clips

Low Coolant & Temperature Alarms

Mason Alarm


Radiador (Fitting Instructions in Spanish)


Radiateur (Fitting Instructions in French)

Rear Heater Matrix

Steel Seal

Temp Gauge