Oil mixing with Water in Reserve Tank - 1980 Volvo GT 242

[Snake710]

Hello: I recently brought my car for an oil change, and my mechanic found oil in the water reserve tank (a thick creamy beige color substance). He flushed the car's system, but cannot find anything wrong. The car is running fine. I was told to drive the car, and keep an eye on the water reserve tank. What do you think is the problem. Thank You, DEE

[MadeInJapan]

Could be a broken radiator (internally) or a head gasket. Did you add some stop-leak? If so, this can also show up in the way you found things (as I found out in our old 850...had to end up changing the radiator anyway). In any regard, I agree with the mechanic...check it regularly....before and after each drive for awhile...if it shows back up it could be fairly serious (expensive) if not taken car of quickly.

[sntee]

I had (have ) exactly the same thing on my 850.

I replaced the head gasket and and thought this would cure it, but the problem seems to be back again. This leaves me with three choices......

1) Head gasket replacement was done incorrectly -

Of all the things that went wrong when I did this job, the actual gasket replacement bit seemed to come together nicely. However, in total it was a massive undertaking and I won't be trying it again in a hurry.

2) Oil hung up in Heater matrix -

After the gasket change, I tried real hard to make sure the coolant system was fully cleaned out. However, its possible that some of the oil got hung up in the heater matrix and has flushed out gradually since. (This is my favourite theory )

3) Bad rad -

The Radiator is less than two years old and is a Nissens (which I'm told are a good quality brand) so I'm less inclined to believe that the problem lies here. Besides which, there is absolutely no sign of water in the tranny fluid and I would expect to get atleast as much liquid going from coolant to transmission as the other way around.

Has anyone got any other suggestions as to where the oil and water may be getting mixed up?

[MadeInJapan]

Three parts to these radiators...engine oil, coolant and transmission fluid. They can leak internally between any of the parts...for instance they can leak between coolant and engine oil but not into the transmission. However with the rad being only 2 years old I hope that your second theory that oil was left in the system is the real case. When it comes up to the top of the expansion tank, use a Kleenex, dip it in and get the gunk out, letting the tissue absorb as much as possible. Then keep an eye on it. Maybe you'll be lucky on this one.

[billofdurham]

One of the major drawbacks of any coolant flush is getting the rubbish out of the heater matrix. I would think old oil would be classed as rubbish!

A tip I picked up many years ago was to flush the heater matrix separately.

Remove the inlet and outlet pipes, set the temp control to max and allow the water to drain out of the matrix. If necessary give it a hand by using low pressure air. My informant had rigged up an adapter that connected to a bicycle tyre pump.

Partially close the outlet using a bottle cork with a hole drilled through (to allow air to escape) and slowly pour near boiling water mixed with your favourite coolant system cleaner into the matrix.

When water runs out of the hole in the cork block it with the reverse end of the drill bit that cut the hole. Wear safety gloves for this part to avoid scalding your hands. Then quickly block the inlet and let it stand for a reasonable time to shift whatever is in there.

Remove the corks and flush out the matrix with hot water several times before reconnecting the pipes.

Bill.

[sntee]

I'll have a look on VADIS later, but I'm fairly sure that my T5 has a seperate Oil cooling rad.

Great tip about flushing the matrix. Perhaps Matthew could clip it out and paste it into the Repair database. It might be useful, even if just to help people to do a thorough job of flushing their coolant system.