V6 Coolant Leak Mystery Problem

[BongoBonkers]

Hi

We have a yr 2000 V6 with LPG. It has a long term minor coolant leak that we cannot find the source of. Basically, coolant very slowly collects in a casting well to the right of the middle spark plug passenger side underneath the cam cover. After 1000 miles or so the coolant builds up enough to begin to spill out of the top of the casting well and drip down the spark plug holes. This causes a misfire. We then remove the coolant from the well using kitchen roll and it's all fine for another 1000 miles ish...

In the course of diagnosing the misfire and trying to fix the leak we have done the following:

New plug leads, new plugs, new distributor cap and rotor arm. New cam cover gasket. Removed cam cover and applied thread seal to hex head bolt found at base of casting well. Cooling system pressure test (result no leak). New coolant and K-Seal added to coolant system.

The van has been to 2 very well known 'Bongo garages' to fix the leak and both of them have failed to sort it.

Has anyone else had a similar problem? Or does anyone have any brainwaves as to what it might be or how to rectify it? All suggestions gratefully received.

The van is fine to drive and we can work round the problem (and have done so for a couple of years now...) but I would dearly love to fix it

[mikeonb4c]

Have you considered putting u/v dye in the coolant and using a u/v torch to trace the source of the leak. Kits can be bought for that.

[BongoBonkers]

Hi Mike

Thanks for the suggestion. Might be worth a go but the area where the coolant collects is fairly well hidden underneath the cam cover, I have to use one of those tiny inspection torches on a stick just to see it and access is really difficult. I will have a look at them on Ebay, I guess if the kit's cheap enough it's worth trying.

Thanks

Dave

[Simon Jones]

The only coolant pipe that passes near the cam cover is the bleed pipe that can been seem here going from top left to bottom right. I guess that has been checked for signs of damage where it clips in place?

[BongoBonkers]

Hi Simon,thanks for the reply.

Yes, no luck there I'm afraid. The coolant actually collects in a well underneath the area of cam cover between the middle and right hand spark plugs in your pic. You can only see it by removing the middle plug cap and poking a tiny inspection light down the spark plug hole and immediately right though a little gap. It really is most bizarre.

The even stranger thing is I've been told by someone who ought to know that there's not really any coolant passage near that area either. If it were oil then it might make sense....?

Simon, you know a lot about Bongo V6's. Could you possibly recommend me a mechanic? I don't mind travelling a bit. We have tried Discount Trucks and 321 Away already with no luck.

Thanks

Dave

[Simon Jones]

Hi Dave, that does sound like a bit of a mystery. I take it there is no doubt it's coolant rather than water / other fluid? It could be spraying up from lower down and then collecting there perhaps. Is your LPG vaporiser on the passenger side? If so, it is likely to be plumbed into the coolant pipe that runs by the chassis member.



You've tried the two places closest to you that I would have suggested. You could try Bellhill near Bath, but when I last spoke to Tom there, he said he was not a big fan of the V6 so he may not be that familiar with them. The only place I've had mechanical work done was at Allan's in Plymouth who did my cambelt and oil seals. Might be worth a phone call to see if he has any ideas to save you a long trip to Devon.

[BongoBonkers]

Hi Simon

Yes it is almost certainly coolant. It took me a little while to work it out and another member (Cheffy?) had I think been posting about spray issues and I was thinking along those lines...but the liquid accumulation I was getting was yellow. I couldn't figure it out but then I changed the coolant and realised the yellow was some kind of Jap market coolant - I hadn't been able to see it was yellow in the semi-opaque plastic header tank. I changed it for blue and instantly the fluid accumulation from then on changed to blue - I'm pretty certain it's coolant. Plus of course the evidence that this problem occurs in dry weather i.e. down to Spain and back last Summer there was no rain but still the same issue.

Plymouth is probably not gonna happen for us. It's a 500 mile round trip and we'd leave it there for them to work on so you're looking at 1000 miles of travelling to drop it off and then pick it up. Thanks for the suggestion though.

[teenmal]

I think these vehicles might have core plugs on the very top of the heads, worth a check. It might also be worth checking the engine oil for water content ( done after vehicle has been standing overnight preferably, taking a sample by removing or slackening the sump plug.)

Good Luck.

[mikexgough]

Having no knowledge of this engine..but... is the Inlet manifold heated per chance?... if it is.... it could be worth a look see at the coolant feed pipes and clips etc... just in case it's a small leak there... I say that as the manifold (looking at images) is above the banks of cylinders... and a drip or mini spray will drop and collect...
Might be suggesting something completely rubbish but check it out and dismiss it or dismiss my opinion... Hope you find the source of the problem

[Simon Jones]

No heated manifold, just pipework to the gas injectors:

[mikexgough]

No heated manifold, just pipework to the gas injectors:

Well that's that idea ticked off....

[BongoBonkers]

Well thanks all you guys for your ideas and efforts. I'm not much further forward but it's nice to know someone cares! I think I might have to let our local 'jack of all trades' garage have a go unfortunately. They can be very good or very bad, hope I get lucky. Cheers all

[apole]

Hi there,

Used to have a V6 on LPG. Fred at Discount Trucks near Newbury knows alot about your car. Also has the right test gear and a proper code reader. Bit of a trip from you but could be worth it.

BPV in Slough also very good, more on the LPG side but familiar with petrol bongos too. Between them they looked after me well in the past.

Out of interest are you loosing coolant at all? Reason for asking is as others have posted, other than the bleed pipe, there aren't any coolant pipes round there. At the rear drivers side top of engine as I recall is a small set of coolant pipes preheating the inlet manifold, maybe dripping down from there? Just a thought. Also check your thermostat housing, sure it's at the front of engine on nearside.

Keep us posted.

Good luck.

Simon, that engine looks immaculate, you been polishing it or something?

Andy

[New Forest Terrier]

I would second Discount Trucks. They look after a lot of petrol Bongos, including mine. Gerry has one himself now. Probably your best bet for finding an obscure fault. They import a few V6s as well.

[Simon Jones]

Simon, that engine looks immaculate, you been polishing it or something?

You know what, it doesn't look that clean in the flesh even though I did give it a going over with Gunk prior to having the LPG fitted. The alloy has quite a bit of oxidation on it & doesn't look at fresh as it should do. I have had a go with a fine wire brush to get the 'fur' off, but it didn't make much difference & to be honest, it's more fun to drive it than to clean it

I do try to keep it fairly clean so any leaks show up. The seals around the rocker cover bolts are weeping a little even after nipping them up slightly. That's on the long-term 'to do' list.