Repairing and Maintaining Your Imperial's Transmission Oil Cooler


Imperial Home Page -> Repair -> Cooling System -> Transmission Cooler

Tip from Kerry:

An overheating transmission will impact the radiator. The transmission cooler in the bottom of the transmission can put a lot of heat into the system. I have seen overheating problems solved by simply going to an aftermarket transmission cooler that is mounted in front of the radiator.

Question from Roy:

A friend of mine bought a 68 NYer a short time ago and I had occasion to look at it this morning. Aside from the usual minor problems, it had a pinhole in a radiator tube just below the tank. We took a quick trip to the auto parts store to get some Alumaseal, however, when I pulled the radiator cap to put it in, I saw the telltale tan color indicating oil in the coolant. When my friend asked what the bad news was I told him it was time for new head gaskets or to ignore the problem and pray it doesn't get worse. Trying to keep a positive outlook, he quizzed me on other possible causes, which left me at a loss. Finally, he pointed to the transmission lines at the bottom of the radiator and asked what they were for, after I explained that they contained transmission fluid, he asked if that could be the cause??? Anybody have any comments on the causes of oil in the cooling system, could it be from the transmission cooler leaking inside the radiator?

Reply from Steve:

I would first check the transmission fluid and engine oil to see if there is any contamination of it too. A pin-hole leak in the transmission cooler that is inside of the radiator tank will put transmission fluid inside of the radiator. When the engine is off, pressure will still remain in the cooling system for a little while if the engine was up to operating temp, the radiator cap is ok, etc...thus putting a small amount of coolant into the transmission lines which will mean slow death for the transmission once the car is used again. The same process will apply if there is a crack in the block between a water jacket and an oil galley. Check the oil to see if it appears contaminated. For a head gasket to blow between a water jacket and an oil galley is not very common. They are more apt to blow between cylinders or cylinder to water jacket....not from water jacket to oil passage. And as far as I can remember...oil does not even pass thru the head gasket area. I believe the top end of the engine is fed via the lifters and pushrods.....and then the non-pressurized oil flows down thru large passages in the top of the head, through the holes near the camshaft and then into the oil pan. Roy, why don't you recommend to your friend to get a auxiliary transmission cooler that attaches to the front of the radiator? Wouldn't it be nice if the transmission cooler in the radiator was leaking and all you had to do was install an aux one thus eliminating the one in the radiator??? I have one installed on my '75 Imp along with a sending unit and gauge to tell me what temp my transmission is running at. It usually runs at about 130 to 150. Heat is the #1 killer of automatic transmissions. Using the one that is in the radiator only cools the fluid to whatever the coolant temp is.  

Tip from Ken:

I suggest a transmission cooler, it would especially be good for the transmission in "parade-type-situations". (The air cooled type that plumbs into the lines to the cooler in the radiator.)   IMHO, the cooler does not *have* to be mounted in front of the radiator to still function, and I think you can get long skinny coolers that are made for the street rod people, that will mount in all sorts of creative places, usually along a frame rail.

Tip from Gary (about Torqueflite transmissions):

I would recommend the Hayden brand of transmission cooler, though any good cooler will work. They are available at any good auto parts store. The Torqueflite has a cooler integrated into the lower radiator tank. The problem with a radiator cooler, is that the transmission fluid is only cooled to the engine coolant temperature (180-200 degrees F). An air to fluid cooler such as a Hayden is far more effective, and helps to keep the fluid temperature lower, allowing for longer seal, band and clutch life.

Tip from PEN (1962):

The '62 does have a transmission filter in the cooler return line. It is about the size of a pint jar, and it is located on the left side of the engine just back of the motor mount. My service manual suggests to change it every 32,000 miles, and I have done so a bit less frequently. It is supposed not to clog because it has a built in bypass valve. These are available from Fram, and more recently I got one from NAPA. Every '62 owner should check out their transmission cooler lines front to back for wear through. These lines can rub up against each other, the trans case, or where any contact is made with metal. They will and do perforate, resulting in leaks which can lead to the destruction of a transmission. The most dangerous spot is where the trans cooler line crosses over the right front brake line directly behind the right side of the radiator. I have had the brake line wear through and burst because of the trans cooler line rubbing on it. It was very scary, so I recommend feeling the lines with your fingers for worn spots and replacing the worn or leaking lines. 

Follow-up from Mark:

 All the '63s had this filter, also.

Tip from Chris:

If you are having problems that you think are stemming from your transmission cooler, make sure to check that none of the lines have kinks and that they are free and clear of all gunk and debris that can cause a slow flow.

This page last updated January 20, 2004.  Send us your feedback, and come join the Imperial Mailing List - Online Car Club