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?

 

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.

 

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.
--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

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.

 

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.

 

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

 

I have never in 15 years found a turbo to cause this problem. Sounds like
from the inspection that the turbo is on the way out but not the
problem.Sounds like a head gasket between 2 and 3. They are the hottest
cylinders. Do a leakdown test

 

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.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

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.

 

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.

 

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

 

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

Cheers, Peter.

 

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.