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bubbles in header tank but not combustion gas

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andy46
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Joined: 15 May 2020
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Location: corby

PostPosted: Tue Oct 19, 2021 14:54    Post subject: bubbles in header tank but not combustion gas Reply with quote

I recently bought a new (to me) 3.0 trooper. Imagine my disappointment when on the way home the eml came on with a loss of power, I checked the guages and the temp was all the way over. I stopped safely within half a mile and switched off. It had obviously lost all ar most of it's coolant. After leaving it to cool for a couple of hours I filled it with water and started the engine. It started easilly and ticked over as well as you would expect for a 20+ year old truck and the eml was out but there was an obvious, sustantial coolant leak towards the rear RHS, getting dark now so recovery called.

I looked on here to find where the leak was likely to be and it was the hard to reach pipe on the back of the engine, I did a temporary bodge to fix the leak while I tried to work out whether the engine was cooked.

It starts and runs fine, if firing on all four (rigged up a temporary harnes between the injector loom plug so I could disconnect each injector individually). It does not overheat - in fact it won't get up to running temp on tickover. However there are bubbles in the header tank. I have pulled the tube out of the header tank and put it in a clear jar with some water so I could see the bubbles clearly - it's no more than me blowing gently down a straw but it is steady and persistent, if they were from an air lock surely they would stop after some time?

After this I was convinced I had a blown head gasket or a cracked head but not being keen to rip the head off I bought one of the tester kits which pass the bubbles through a blue liquid which turns yellow if combustion gasses are present, to my surprise it stayed blue, I even tested the test by rigging it up to the exhaust where it immediately turned yellow and shot all over my face.

I have repeated the tests with a little more care with the same results but without the facial.

The system seems to be pressurizing but not excessively - although the pressure is obviously releasing via the header tank tube and I haven't got it hot. there is a slight puff of escaping gas when removing the radiator cap.

So, please, where might my bubbles be coming from?
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PostPosted: Tue Oct 19, 2021 14:54    Post subject: Google Ads keep this community free to join!


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eithan h
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PostPosted: Thu Oct 21, 2021 21:09    Post subject: Reply with quote

what year trooper
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andy46
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PostPosted: Thu Oct 21, 2021 23:56    Post subject: Reply with quote

reg jun 2000
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andy46
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PostPosted: Fri Oct 22, 2021 0:01    Post subject: Reply with quote

I took it for a run yesterday and got it up to normal temp, after it had cooled overnight it needed topping up with about 1 litre of water. The passenger side footwell was very wet but it rained heavilly overnight. I took it for another run today with the heater bypassed - will check level in the morning.
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andy46
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PostPosted: Fri Oct 22, 2021 8:25    Post subject: Reply with quote

So having run (driving) it up to temp with the heater matrix bypassed then parked it inside and allowed to cool overnight it appears to have lost just under 1 litre of water (not using coolant untill I can solve this). So it may have been losing some thro the heater but I don't feel that that this is a conclusive result having only tried it once and it doesn't explain the bubbles.
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eithan h
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PostPosted: Fri Oct 22, 2021 20:32    Post subject: Reply with quote

obvious is head gasket especially if the temp gauge was right over, other points i've had leak is inlet manifold cracked, egr cooler if it's fitted and injector sleeves not sealing in the head
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andy46
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PostPosted: Fri Oct 22, 2021 21:19    Post subject: Reply with quote

I was convinced it was head or head gasket untill I checked it with one of those blue liquid tests - is it possible for those to get it wrong?
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eithan h
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PostPosted: Fri Oct 22, 2021 21:48    Post subject: Reply with quote

yes they are not the most reliable things
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andy46
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PostPosted: Sat Oct 23, 2021 19:00    Post subject: Reply with quote

Thanks Eithan, I absolutely agree that the obvious reason for my problem is a head gasket but as a DIY spanner monkey I need to be 100% sure before I embark on replacing one on one of these engines - hence the test kit. As I understand it this test is very accurate at detecting combustion gasses but if the head or gasket has failed in such a way that it is not allowing combustion gas into the cooling system, then they're pretty useless.
I don't see how such a failure can allow coolant into the combustion chamber and not allow combustion gas back into the coolant, but I'm open to being corrected.
I definitely have a coolant leak and it's definitely not an external one, it doesn't appear to be entering the oil so it must  going out the exhaust or into the fuel tank.
I understand that leaking injector sleeves can put coolant into the fuel and that can be checked by getting a sample from the fuel return pipe.
EGR cooler and or turbo housing (another suggestion from elsewhere) can both be checked by temporarily bypassing each as i did the heater.
Inlet manifold can be inspected as I start to strip it down for a HG.

If you can spot a flaw in any of my reasoning pls shout.

Are OE head gaskets still available? I believe pattern ones are not recommended - I won't be ordering one until I have had the head properly inspected but have access to a workshop very capable of doing such an inspection (or of the inlet manifold).
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eithan h
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PostPosted: Sat Oct 23, 2021 19:13    Post subject: Reply with quote

on a sleeve the section below the lower o ring is coolant, the sleeve end is a tight fit in to the head and thats all that stops coolant going in to the combustion chamber so if that fit gets a bit sloppy then it's possible that the piston on the suck stroke could suck coolant past the end of the sleeve. this could be made even more possible if where the sleeve butts up to the bottom of the head it is all pitted which does happen on this engine.
head gaskets are still available from the dealers and i think they are about £80
i don't use these kits myself as i don't trust them, i normally find myself doing head gaskets from about 150k mls upwards anyway so if it's close to that mileage then it might be worth doing anyway
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andy46
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PostPosted: Mon Nov 08, 2021 13:37    Post subject: Reply with quote

So the head is off. The gasket appeared to contain water (but not rust) between it's leaves which obviously isn't good but I can't see anywhere there is an obvious bridge between a waterway and a combustion chamber and still no sign of water in the oil. The sealed edges of the gasket around each cylinder appear to be intact.

No 2 cylinder is getting wet - there was a small amount of water in it and with the exhaust manifold off it is obvious that water is flowing from No 2 (brown rusty marks inside the head and manifold).
The appearance of these marks suggest that they were present before the engine overheated.

The bottom of the injector sleeve appears shiny on No 2 - the others have carbon deposits. Should this sleeve be removed for inspection? and if so how?
All injectors are very similar in appearance, the conical copper washer was slightly stuck to No 2 injector - 1 and 4 remained in the head untill I turned it upside down, 3 lifted off easily.
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eithan h
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PostPosted: Mon Nov 08, 2021 22:30    Post subject: Reply with quote

the sleeves can be knocked out from the combustion side now the head is off, check for pitting inside the head where the sleeve sits the heads are known to pit underneath the sleeve seat
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andy46
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PostPosted: Sat Nov 13, 2021 12:34    Post subject: Reply with quote

I may have found the problem.

I removed the sleeve and it looks fine, as does it's seat in the head. The rusty water marks appeared to be concentrated around the front exhaust valve so I removed the valve. The bottom of the guide is very rusty and a little damp even tho the head has been on the bench for over a week.

Is it known for the guides to allow coolant past into the exhaust port? Are they replaceable in a home workshop?

Of course it could be a crack in an area of the head which I still can't see - how likely is that?

I'm beginning to think the head is scrap which is a bit of a problem as replacements seem to be priced at around half the value of the car.
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eithan h
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PostPosted: Sun Nov 14, 2021 23:25    Post subject: Reply with quote

have you got an egr cooler on that model?
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andy46
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PostPosted: Mon Nov 15, 2021 20:09    Post subject: Reply with quote

No EGR cooler on this, I think it's too early, 2000 W reg. If there had been one I would've investigated it long before taking the head off. The rusty water marks are only on the exhaust port for cylinder 2, the other 3 are just a little sooty as would be expected.
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