Overheating issues

[hellopablo]

Hi all,

My bongo has had some overheating issues recently so I took it to the garage (who have experience with bongos) who replaced a dud thermostat and replaced/bled the coolant.

For a short (number of days) while everything seemed to be ok, the temp gauge stayed at around 11 o'clock while driving about town, previously the needle was racing into the red after 15 mins or so of city driving.

However, I took it on a longer drive (~300 miles) and for the better part of the journey the needle was right at the top once again (just under the "100%' mark). We stopped a few times to let it cool right down, but the needle was right back up there again by the time we left the service station!

I have checked the lower hose and it's getting hot, which suggests the thermostat is opening.

I obviously need to take it back to the garage, but I'd like to do any simple DIY I can before spending the money. Any hints? I'm not at all technical and don't have access to many tools, ramps etc. I have attempted to do some research but the existing threads are long and seem to be very specific - I get a bit lost in them if I'm honest.

Thanks in advance for any help, I love my bongo and would hate to resent it due to a ridiculously expensive mechanics bill!

[Gasy]

I think you should take it back to the garage
Tell them it's still running hot
Bongo cooling systems are tricky
And very expensive damage if done wrong

Is the water level ok

[Bob]

Hi and welcome.

If you have little technical knowledge the Bongo cooling system is not for messing with.

This doesn't sound too good so I would recommend recovery to a Bongo savvy garage, damage may have been done before the stat was replaced, but a genuine Bongo garage should have picked this up.

Underlying problem seems to be driving it for '300 miles with the needle right at the top, stopping to let it cool down'.

This might be a significant bill but Bongy will be worth it. Honestly, not something to skimp on.

[haydn callow]

Agree with Bob......doesn't sound good......never drive a Bongo if the needle moves past 11 o,clock
(Unless it's been modified)

[Simon Jones]

Have you checked the level of coolant in the header tank when cold? After a bleed, the level tends to drop for the next few runs but if it drops too low, it will allow air into the system which is where problems start. If you haven't already got one, get a low coolant alarm which will give you a heads-up of this type of thing.

Also, what engine have you got? V6 and diesel are bled using the same method but 2 litre has a different arrangement.

[hellopablo]

Thanks for all the replies - an overwhelming "don't drive and get 'er checked!".

The garage is one I found on here and they tell me they have other bongos on their books, however I'm a little concerned that it's still overheating despite being in with them twice (both for overheating issues). Can anyone recommend a garage in (preferably East) London who I could maybe seek a second opinion from?

It's a 1997 2.5L diesel - not sure if it's a V6 or not!

[haydn callow]

Thanks for all the replies -

It's a 1997 2.5L diesel - not sure if it's a V6 or not!

There are 3 Bongo engines

Yours which is a 2.5 diesel

V6 which is a 2.5 petrol

2ltr which is a straight 4 petrol

[hellopablo]

Ok, bit of a weird one - wonder if anyone has any ideas, please read on...

So, this morning I checked the water levels thanks to a few tips here, and it looked a little low. I added about two litres to top it off, until I could see the water level in the header tank was at a "normal" level.

I decided a short test drive was a good idea to see if my newly topped up water levels solved anything. The van had been on the driveway for a few days and I noticed that there were no puddles/leaks etc when we drive off - it had NOT been leaking.

However, after about 2 miles the needle shot up to the 2 o'clock position (i.e 100%) and by the time we pulled over at a safe place I could hear the header tank bubbling and even a few pops and hisses (imagine an compressed air valve being opened briefly). We popped the hood and, sure enough, steam everywhere and water clearly visible inside.

Fearing the worst we called the AA, who came out very quickly. The first thing he did was put about 4-5 litres of water in - I'D ALREADY FILLED IT UP! He explained there was a leak and a pressure test would reveal where. One pressure test later and he's scratching his head, it was maintaining pressure and no water dripping from anywhere. He reckoned the header cap had done it's job and released the pressure - explaining the water inside and around the engine, but was a bit stumped as to why it needed so much filling up in the first place.

With it filled up again we drove the 5 miles back to the house and sure enough, because the mechanic was watching, she behaved herself and stayed cool the whole time.

So, with the van feeling healthier and my confidence a little higher I decided to attempt the 300 miles back to London (in reality I was going to do it anyway, had no choice really!).

The needle stayed between 11 and 12 for about 100 miles before slowly creeping back up. I stopped, let it cool and then topped it up with a fairly significant amount of water (can't say for sure how much, I did it from the water & air machine at the service station, but it was more than a little splash). Again, no puddles at all in the 30 mins or so I was stationary.

Continued another small while before stopping for some food, checked the tank and topped it up with some water we had in the van, about 2-3 litres worth. From here on out the needle stayed a steady 1-1.30 (~75%) for the rest of the journey. I was maintaining about 60Mph.

In the last 15 miles or so, seemingly randomly, the needle went from 1-1.30 back down to 12 and stayed there. Finally, I parked up, and as I was leaving the van I heard the gurgling and thought F**k this, I'm going to bed.

So, to summarise: where is all the water going if it's not leaking and maintaining a pressure test; what's the next sensible step (i.e what do I ask the garage to check for)?

Any thoughts welcomed and appreciated!

[hijimhere]

Lets go back to basics -

1) What did the garage do to "bleed" the system?

2) What mix of coolant and water is present (50/50 would be good)

A) If the garage did not bleed using the known method you may have an air lock! It is essential that the bleed hose is used to with a funnel to get air out of the cylinder head.

B) with a very weak coolant mix the temperature/boiling point could be lowered dramatically.


that having been achieved - the next tests are
1)engine warm pressure test of cooling system - if pressure drops and no leak is observed the problem is internal

2) engine warm block test - not all garages recognise this old test - sample of coolant is test for hydrocarbons! Sample will turn from deep blue to a puse green if hydrocarbons are present. This means the problem is internal.

[Simon Jones]

To be honest, if you needed 2 litres to bring it back to the correct level, then you really needed to bleed it to get the trapped air out. It's since lost another 4 or 5 litres and the gauge has been at 100%. If you've got no obvious external coolant leak then putting all the symptoms together tends to point to a cracked cylinder head. Whether that was the initial problem may never be established: it may have just needed a small top up but has been allowed to drop which has introduced air into the system.

Continuing to drive it with low coolant or air in the system will almost certainly have finished off the head.

[haydn callow]

Me thinks a new head will be required.....do find a garage or mechanic who has lots of experience with Bongo cylinder head replacement.....failing to do this could find you back where you are now a few weeks later and about two grand out of pocket.

[Klunk]

Hi hellopablo, did you manage to get to the bottom of this? I ask as I have a near identical problem.

I have just go back from a trip into and around the Limousin, France. Got back early hours this morning and all was fine. The van spent the last two weeks up hills and ploughing through the forest of the Millevache and she did not miss a beat. Anyway got up this morning after getting a distress call from her indoors. She had crept out with the youngest to do a bit of shopping and was stranded at the local Mozzas with a flat battery. It's only a mile away so I ran over there in the van, jumpstarted her car and drove back. Well about 2 minutes from home and I smelt the hot coolant and spotted the steam coming out the corner of the bonnet. I pulled over and let it cool down and sure enough the coolant was down a little, but no more than about a pint. I topped it up with some premixed I had in the van and got her home.

On inspection I found no leak or any other obvious signs of trouble. I topped up fluid and ran the engine and within a matter of minutes the fluid started pouring out of the expansion tank. None of the pipes seemed to be hot so I'm hoping it's just a sticky thermostat and not head issues. Can only cross fingers and see what tomorrow brings

[Simon Jones]

First thing you need to do is have a good look around the engine & under the van to see if there is any sign of a leak (either letting coolant out or air in). Then it needs bleeding with the header tank expansion cap off to ensure you get all the air out of the system. After that, refit the cap having checked that the spring & rubber seal is in good condition. Hopefully, the level will only go up a little amount & the pressure will not build up. Fingers crossed.