I am looking for some pros and cons on the turbo oil filter housing oil cooling vs later style elimination of the oil cooler in favor of another water cooled one.
The '91 I have has the external oil cooler attached to the radiator, while the '94 lacks that set up--the oil filter housing is different with coolant lines instead of oil. Has anyone done that conversion? Since the later models are that way I imagine it was an improvement?

Hello
the older style setup i believe has a thermostat and only opens when it hits a certain temp.
i dont know whats better but i will take the newer style.
the hoses on my two 940 turbo cars are over 5 years old and i will be putting new ones on there real soon.
thats where i use volvo hoses and not aftermarket.
good luck
Mike

I assume you are referring to the oil coolers on the later 900 turbos that is at the base of the oil filter versus the earlier set up of a cooler beside the radiator.

I do not know how efficient one versus the other is but I do know that the later type seems to be a poor design in my estimation. Filter changes expose those coolant lines to a lot of oil because of their location and it simply accelerates their deterioration.

They are not difficult to replace but I look at them as maintenance items that need to be watched and replaced when they start to get "spongy". It is a good place for a rupture to occur and drain the coolant in short order- another good reason to equip your car with a low coolant warning circuit.

Randy

Unless I'm really confused. Pretty sure all turbos need oil for lubricate. Then you have some that are air cooled and others water cooled. My old garret T3 is oil lubricated with water cooling.

"the oil filter housing is different with coolant lines instead of oil."

If this were the case, you would be mixing oil and water. If you are saying the "separate" oil cooler is gone, and the lines run to the passenger side of the radiator. If so, where those lines run into the radiator is separate from the internals of the radiator. Normally auto trannys have the tranny oil running to these connectors on the radiator as a tranny oil cooler.
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Post Back. That's whats makes this forum work.

I am assuming the later turbo oil cooling setup discussed here is like the one on my S90. Small diameter (5/8?) engine coolant hoses go to a casting bolted to the engine that forms the oil filter base and in there, but in separate passages, heat is exchanged between the oil and engine coolant. In other words a liquid-to-liquid heat exchanger rather than liquid-to-air. It is more efficient to exchange heat liquid-to-liquid so this thing can be smaller than the oil cooler mini-radiator of the earlier cars.

Engine coolant heats up quicker than the oil after a cold start, so this later heat exchange method starts off by warming the oil up - a good thing. At full engine temperature the coolant is at about 92C (197F) which is the "right" temperature for best performance of engine oil.

The engineers' logic behind these engine coolant-to-oil heat exchangers is to maintain oil temperature closer to the ideal, and to do so earlier in the cold start cycle. And the accountants' logic may be that they are cheaper both in parts cost and assembly line time.
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Bob: Son's XC70, daughter's 940, my 81 and 83 240's, 89 745 (V8) and S90. Also '77 MGB and some old motorcycles