Bongo Fury

Hi Everyone,

I am new to the Forum but not new to Bongos having owned our 99 V6 for just over 2 years and I was hoping some of you may be able to offer some advice and I guess a sanity check on my current thought process to diagnose my Bongos current issues.

My V6 overheated today on the M27, I was not in the Van but my wife reported that in the very hot weather and in stop start traffic there was a smell of coolant, a whirring noise like a pump with nothing to pump through it and the temp gauge shot up. She pulled over and turned off immediately and we arranged for the Van to be collected on a flat bed and returned home.

When it got recovered I inspected it thoroughly expecting to find an obvious leak or split hose, but the only evidence of lost coolant is around the expansion tank blow off/vent hose. It seems to have only lost about half a litre of coolant maybe slightly more which seems commensurate with an overheat / boil over.

I have refilled the system and run the engine back up to temperature (I have not bled it yet) to try and identify any leaks but there is not a whiff of a leak anywhere that I can find and I had it running for a good half hour or more going over every pipe and clamp with a head & hand held torch.

What there is however is a clacking noise at idle which sounds a little bit like a zip or button in a tumble dryer coming from the front of the engine, loosely in the same area as the water pump. I heard this noise recently and thought it was the auxiliary pulley as it jingles a bit when under load, but now I am not so sure. (I have taken a recording of the noise but there does not seem to be a way to embed in my post so I assume I need to link to somewhere the file is hosted).

I have run out of time / daylight this evening to investigate any more and my current train of thought is:

1. Pressure test the system - does anyone have a suggestion on the best way to attach a car valve to the hose on top of the expansion tank? I have some old inner tubes I can use and a foot pump with gauge, just not sure on the best way to get it on there?
2. Check the Water Pumps operation - any suggestion on the best way to do this? Any thoughts on the noise?
3. If neither of these comes up with anything I guess maybe a sniff and compression test, to make sure there are no head / gasket issues
4. Full drain & chemical flush to check for any blockage or crud build up
5. I am out of ideas

It goes without saying it wont be driven anywhere until this is resolved but that does make it an urgent issue as its our main vehicle and in constant use.

Also as a last bit of info as I guess someone will maybe ask when it was last bled, it was approx a year ago when a new Thermostat was fitted, it was done by a Bongo savy Garage in Fareham at the same time as the Cam / Crank seals and cambelt.

Sorry for the long winded post and thanks in advance for any help.

i assume its similar to diesel with 3 belts,2 on alternator ,water pump one on a/c pump

are they all there

also on some diesel the rubber that bonds the 2 alternator belt pulleys to the inner bit fixed to engine shaft have given up

ad whilst it looks ok is infact its just floating and not beiing driven

the first water pump i changed on mine the veins inside on the impellor had broken of and that made a wierd noise

The whirring noise that was heard at the time of the over heat could have been the scavenger fan cutting in to cool the engine bay. If it was stop start in hot weather there would have been no air flow through the engine bay as the van wasn't moving. Perhaps the temp sensor for the scavenger fan is cutting in to late. It is exactly this type of situation that the scavenger fan is designed to deal with. Perhaps in the heat we've been having the over heat was a direct result of scavenger fan failure. I have personally fitted an override switch for the fan to my V6 so that in circumstances such as you described I can manually switch the fan in. After all the vans are getting old now & I'm sure that tolerances of ageing sensors must change with time.
I would check that the fan does run & that the temperature sensor works as it should. There is a section in the engine manual if you have one covering how to test the sensor.

Cheers

windywatson wrote:The whirring noise that was heard at the time of the over heat could have been the scavenger fan cutting in to cool the engine bay. If it was stop start in hot weather there would have been no air flow through the engine bay as the van wasn't moving. Perhaps the temp sensor for the scavenger fan is cutting in to late. It is exactly this type of situation that the scavenger fan is designed to deal with. Perhaps in the heat we've been having the over heat was a direct result of scavenger fan failure. I have personally fitted an override switch for the fan to my V6 so that in circumstances such as you described I can manually switch the fan in. After all the vans are getting old now & I'm sure that tolerances of ageing sensors must change with time.
I would check that the fan does run & that the temperature sensor works as it should. There is a section in the engine manual if you have one covering how to test the sensor.

Cheers

Or even radiator fans coming on, as they're even more important in preventing overheating? Same observations about ageing sensors apply!

Thank you all for responding.

I have added checking the radiator flow and function to my check list.

Regarding the scavenger fan am I right in saying this is the one that faces back toward the engine and looks a bit like a desk fan? If so I think you may be right about this being the whirring noise as talking over with my wife and daughter they say it sounded more like a fan that was sticking than a pump. I tried turning it by hand and it's quite stiff in engagement so another thing to test/check.

The radiator fans come on fairly regularly and the noise is well known. It's done this for 2 years of ownership and 30+ k miles so I assumed normal due to the unusual design of the cooling system but research last night suggests that they kick in quite late when the engine is already running hotter than is ideal?

Scavenger fan is the one you describe.

Rad fans come on regularly when a/c is on. Without a/c, on the diesel they only come on in extreme situations.

Thanks cmm303.

My current train of thought is that the Petrol should run slightly cooler day to day due to the lower combustion temps etc over the diesel, also I would assume the lack of a turbo and associated hot running items must make for generally cooler operating temps, so the regularity of the main rad fans operation, especially as we rarely use the a/c is definitely cause for concern and I'm guessing at this stage indicative of general high operating temperatures.

Can anyone with a V6 comment on how often their rad fans turn on, particularly without the a/c on?

Thanks

lb81 wrote:Thanks cmm303.

My current train of thought is that the Petrol should run slightly cooler day to day due to the lower combustion temps etc over the diesel, also I would assume the lack of a turbo and associated hot running items must make for generally cooler operating temps, so the regularity of the main rad fans operation, especially as we rarely use the a/c is definitely cause for concern and I'm guessing at this stage indicative of general high operating temperatures.

Can anyone with a V6 comment on how often their rad fans turn on, particularly without the a/c on?

Thanks

I think it is a cause for investigation if not concern. I have a diesel and in 10 years of ownership have only caught rad fans coming on once without aircon on. Mind you i don't do a lot of hot day traffic jams up here. My scavenger fan has always felt a bit stiff to turn also but seems to work fine so hopefully it is normal.

from the clues i would hazard a guess at the crankshaft pulley torn apart as in the above comment. not sure if its the same construction as the diesel but its worth seeing if you can spin the belt/s with the crank staying put.

elevated temps, no sign of a leak, tapping sound on tickover,fans on more often,incident happened in traffic when there is little through air flow.

http://lushprojects.com/bongopartsmk2/c ... mgno=.html.


diesels fail like this link.
http://igmaynard.co.uk/bongo/forum/view ... ey#p637393

lb81 wrote:Thank you all for responding.

I have added checking the radiator flow and function to my check list.

Regarding the scavenger fan am I right in saying this is the one that faces back toward the engine and looks a bit like a desk fan? If so I think you may be right about this being the whirring noise as talking over with my wife and daughter they say it sounded more like a fan that was sticking than a pump. I tried turning it by hand and it's quite stiff in engagement so another thing to test/check.

The radiator fans come on fairly regularly and the noise is well known. It's done this for 2 years of ownership and 30+ k miles so I assumed normal due to the unusual design of the cooling system but research last night suggests that they kick in quite late when the engine is already running hotter than is ideal?

I'll stick my neck out & say the scav fan should turn quite freely.. Even on its own driving at high speed?
I fitted a scav fan warning light (red led flasher.) should the fan come on? To my old 95 diesel tintop. But what I noticed at speeds above 70, (Geman autobahn.) was the LEDs flashed rather dimly (noticeable at night.) as the fan motor acted a little like a "dynamo".. Lol

This never happened in the UK.

Northern Bongolow wrote:from the clues i would hazard a guess at the crankshaft pulley torn apart as in the above comment. not sure if its the same construction as the diesel but its worth seeing if you can spin the belt/s with the crank staying put.

elevated temps, no sign of a leak, tapping sound on tickover,fans on more often,incident happened in traffic when there is little through air flow.

http://lushprojects.com/bongopartsmk2/c ... mgno=.html.


diesels fail like this link.
http://igmaynard.co.uk/bongo/forum/view ... ey#p637393

Indeed the crankshaft pulley will make an unhealthy chatter on idle if the rubber bonding (I belive to counteract vibration?) on the fly wheel degrades? I've had this happen in my old vans history too!

Thanks.

The crankshaft pulley has been suggested elsewhere as well and seems to be a very good place to start based on the symptoms. It may explain the hot running if its not turning the water pump over properly.

I have a busy day tomorrow!! But hopefully if I can identify whats caused the overheat I can then test to see if there is any obvious head damage

lb81 wrote:Thanks.

The crankshaft pulley has been suggested elsewhere as well and seems to be a very good place to start based on the symptoms. It may explain the hot running if its not turning the water pump over properly.

I have a busy day tomorrow!! But hopefully if I can identify whats caused the overheat I can then test to see if there is any obvious head damage

Hey don't forget the possible knock on effect to the alternator lagging with its output too...

Out of curiosity. Do you have a Mason alarm fitted?? Sometimes, any charging issue to the starter battery manifests itself with the Mason acting strangely, or even sounding the alarm falsely...?! The aforementioned question is in context with the crankshaft pulley operation.
(Not trying to muddy the waters on your investigation.)

I would suggest that your engine has been running hotter than usual for some time. Nether of my V6's has the cooling fans come on that frequently that I regularly hear them. Only notice them running when Air Con is on. I would check that the thermostat is operating correctly. Not easy to do unless you have a good thermometer to check the temp at the top hose when the stat opens.
May actually be worth investing in a new stat anyway & having the coolant system flushed at time of fitting.

Cheers

You will probably find that the V6 has a solid crank pulley and not the harmonic type that the diesel uses, also the v6 will probably use only 2 belts of the horizontal fine ribbed type, rather than the 3 belts (used on a grooved pulley)that the diesel uses.

Never the less it is worth checking that the pulley is in fact secure.

Good Luck.