http://www.classicsaab.net/gallery2/mai ... emId=21670

I have never seen, or heard of these. Do they work? Any thoughts?

The liquid to liquid coolers do work but its important to note that they wont offer as much cooling potential as a liquid to air. The rate of heat transfer should be better with liquid to liquid because the liquid is a better conductor than the air. However when running coolant as your cooling liquid it won't ever drop below 180 deg F or so. One of these units would help warm the oil up on cold winter mornings though.

They pollute your oil with coolant when they corrode from the inside. VW has a big prob with those on the 1.8 turbo engines. I had a passat come in my shop and we put a 4 grand rebuilt engine from Volkswagen in, total was 6 grand. I dont recommend using water to oil coolers. The C900 engine has a thermostat in the oil filter housing that doesnt open the flow of the engine oil to the oil cooler lines until it is at operating temp, its a very nice design.

I have a couple of these from 99/900 Automatics. They work OK to keep the trans cool, but mine would cause boil over while crawling around in the mountains, even w/ the engine running cool. They help overload our already overloaded radiators, at least in hot climates where you really need a cooler. That said, I may use one for a manual trans cooler on my LSD trannys.

99Super wrote:I have a couple of these from 99/900 Automatics. They work OK to keep the trans cool, but mine would cause boil over while crawling around in the mountains, even w/ the engine running cool. They help overload our already overloaded radiators, at least in hot climates where you really need a cooler. That said, I may use one for a manual trans cooler on my LSD trannys.

keep in mind that ATF has an ideal operating temperature and part of the reason they use a coolant to oil exchanger is that the coolant helps warm up the ATF. So for use as an oil cooler it is not very good as it dumps it heat into the coolant and the coolant never gets colder then 170-180 deg F.

Interesting. I was thinking about using one on my manual trans for my 99 t16V project.

Downsides:
Contamination of coolant and oil (when they fail)
Tax the cooling system, causing more overheating in the summer

Upside:
Less space then a air to oil cooler (relevant for a 99)
Warms the oil in the winter


Anyway I don't think I use one then.

What do people do that run transmission oil coolers in the winter?
Where do you hang one on the already crowded 99, with an intercooler and engine oil cooler?