940 turbo leaking

My 95 940 2.3 Turbo had a bit of a leak which has now expanded to extreme swallowing of water. In the morning there is a wet patch on the join between manifold and Turbo. This morning I tried some radweld, but on the way home on a motorway journey the cooling system almost completely emptied and the engine overheated, bright red turbo etc. Luckily I had plenty of water which just got me home over about 20 miles. The wet patch has been there for some time and I had put it down to some top speed trials with turbo boost turned up and comdemned the turbo as it was starting to use an annoying amount of oil.

When I got to a water source near home I tried to undo the filler cap but was presented with severe eruptions from the water bottle, and what felt like bumping and bubbling from the system.

When it was eventually cool enough to open I filled it again, ran the engine and noticed that on reving it a little the water frothed up.

Is this classic head gasket failure, should I go for the Turbo or both?

-- Tony Stanley

Reply to
Tony Stanley
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If you're talking about froth in the reservoir that may be normal (no idea how the 9xx are setup) but I changed the coolant in my 850 today and there's a line from the thermostat housing to the reservoir which seems to always run a bit of water through it. It frothed a little in the reservoir but settled down just after sitting a few.

Reply to
Franz Bestuchev

Yes sounds like head gasket failure (or a warped / cracked cylinder head). Don't condemn the turbo just yet, it's possible all your problems stem from the cylinder head.

Reply to
Mike F

Well got the Turbo off for starters, and its mush. About 6 cracks on the exhaust inlet port, and some all the way through, surprising it was in one piece, also crack around the centre join. Will try and get a picture uploaded. Manifold also cracked, but could be repairable.

Possiblly this was due to the overboost and top speed test, or could have been the overheat and glowing turbo that occured after all the coolant was lost. I have been fairly diligent with the cooldown and warm up, but it is enough?

Does this means the Turbo is worth nothing in the exchange system?

Would uprated water flow to the Turbo help, it could also be set to continue with the engine off?

Started to get the head off as darkness arrived. I went to get the front crank pulley off and tried to apply my patent flywheel lock by dropping a socket down the sensor hole. However this engine its a little different to the older 360s I have worked on, and there is a weak insert in the bell housing that the sensor bolts into. This insert broke and looks like to replace it needs the bell housing seperated an inch or so, I think I have to knock a bracket up.

Any suggestions on flywheel locking or insert replacement? Manual is useless, and leaves this bit out.

-- Tony Stanley

Reply to
Tony Stanley

Likely the cracking was caused when the coolant was lost, if part of the turbo had coolant and part was red hot that could easily crack the cast iron. As for locking the flywheel, to get the crank pully off I've always just put a beefy socket wrench on it, wedged the handle against the water pump and bumped the starter, always worked like a charm.

Reply to
James Sweet

This does indeed work on (most or all) Volvos, but be aware that most (most or all) Hondas rotate counterclockwise. Not only won't the bolt come loose but the handle can be launched - especially if it isn't a ratchet. Just a general caution....

Mike

Reply to
Michael Pardee

Reply to
<grays560

I don't imagine that improved water cooling will help with the type of problem you have with yours - remember not too long ago, there was no water cooling at all in the turbo - it just relied on the oil to take the heat away. Water cooling the turbo keeps the oil cooler, hopefully below its sludging temperature, and also is especially helpful after the engine is shut off when the oil flow has stopped because the local heating causes a certain amount of flow. I know some Audis use a pump in this circuit.

Reply to
Mike F

Well I hadn't got the head off at that stage, but the gasket looked as if it had failed. It was an aftermarket gasket and looked like someone had tried to cut the gasket to match the water ways and damaged it in the process. In the gasket I put in (Non-OE) there was a 3mm hole instead of the moon shaped water way in the block and head, but I left it as it was.

The car was actually running fine after the major loss, if run gently, warmed up carefully etc but using about 1L of water per hour. So I'd say it was the head gasket that was the main problem, as that goes intermittent on non-turbos. I probably could have put the turbo back on, but it was leaking some water (dilution of anti-corrosion additive will eventually lead to head failure again) and it was whining and using oil, so I thought it better to replace.

Its not clear what happen first, but I suspect the overpressure turbo contributed. The head did the water swallowing trick on the last trip probably caused by the weakened gasket by the poor work and overpressure gasket.

All in, it cost about GBP600 with me doing all the work (thankfully ECP took back the cracked turbo), which if caused by the overpressure turbo well worth the money for the fun I had. I'd still consider doing it again with a few more measures, such as an on/off button and no long full welly tests.

-- Tony Stanley

Reply to
Tony Stanley

Sounds like the fellow who changed the gasket did not retighten the head after 1,000 miles. This is a must on the 200/700/900 series cars even diesels.

Cheers, Peter.

Reply to
Peter K L Milnes

Even with the newer stretch bolts? I've never retightened those.

Reply to
James Sweet

You would if you fitted a new set every head gasket change like you are supposed to.

Cheers, Peter.

Reply to
Peter K L Milnes

My rule of thumb has been to reuse those once, never had a problem with it. The old rigid bolts have to be retorqued after warming up to full temp and then cooling for 30 minutes, I actually prefer that as they can be reused as long as they're in good condition.

Reply to
James Sweet

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