I have a problem with my 940T but this one has me baffled. As of late, every few months my vehicle runs low on transmission fluid (ATF Dextron III) to the point that I have to add a couple of litres (quarts). I do not know where it goes. For a short test, after fluid addition, I put the car in drive with the handbrake on and ran it for 15 minutes. No sign of leaks anywhere. The fitting for the fill tube at the transmission end is tight and dry. The fittings for the oil coolant lines at the transmission are tight and dry. The fittings for the oil coolant lines at the radiator are tight and dry. The lines are also dry. So, where could this fluid go? Does anyone know what is inside the radiator for the transmission oil cooling system? This whole thing is unique and maybe someone out there may have a bright idea. Meanwhile, I keep adding ATF.

 

Check your engine coolant to see if the trans fluid is mixing in. On rare occasions you may develop a leak within the radiator between the trans cooler & radiator. However, usually you will get coolant in the transmission as well

Another common area for leaking is the rear trans seal. There is a bushing for the rear trans shaft that wears out and causes the rear seal to leak. This is easy to see as there will be trans fluid on the underside of your car.

 

When I looked for leaks with the engine running in drive, there was none from the rear of the transmission. Also, if it leaked there, I expect that some residual oil would show up on my garage floor after parking it there for overnight or days on end. So far all is clear there. Thus I suspect the radiator.


It appears to me that the trans oil cooler is built in and an integral part of the radiator. If there is a leak there, I suppose there is not a good way to test it. What exactly would the coolant look like with ATF in it? And if it does go there, would I not see an increase in coolant level in the expansion tank?

 

It appears the ATF is actually entering the coolant inside the radiator. I found the coolant expansion tank MT and it showed some pink residue. Then I added Volvo coolant (50:50 mix) and up came a bit more of the pink scum. I took a couple of photos but could not upload these. Looks like a radiator replacement is in order. I also found a small leak at oil cooler hose leading to the turbo (bottom right side of engine under the oil filter) and this likely explained the reason for the MT expansion tank and why coolant volume hadn't increased with the additional ATF.

 

If ATF is entering your radiator, then coolant is also entering your transmission. So when you put in a new radiator make sure you flush your tranny and replace the fluid.

 

Yes, thanks, that was my plan. I'll also do the water pump since there is 108k miles on it and it does squeal a bit. The job will have to wait until after Easter.