Troubleshooting Transmission Fluid And Engine Coolant Mixing On 2003 Cadillac CTS

Updated 03/20/2015 | Published 03/19/2015

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Derale Series 8000 Plate-Fin Transmission Cooler Kit w/Barb Inlets - Class III - Efficient

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Question:

Im not familiar with the car myself. Its my brothers car. The transmission quit working and apparently, the tranny fluid has gotten into the engine coolant. Folks are telling me that the tranny cooler is under the Intake Manifold... Which is kinda strange to me. I am under the impression that this is a common problem for this particular vehicle. My brother is on a fixed income and cannot afford to either buy another car or spend Thousands of Dollars to get this one fixed. Q1: Where exactly is the tranny cooler located? Q2: If it is under the intake manifold... Can an external cooler be used? If so, what about the sensors? I would greatly be thankful for any information/guidance you could give me. Thanks Sincerely

asked by: Dan P

Expert Reply:

Sorry to hear about the problems with your brother's 2003 Cadillac. The first thing you will want to do is have the transmission taken care of.

I am not aware of a separate cooler for the transmission located under the intake manifold. Typically what is used is a line that runs from the transmission to the radiator. The radiator holds engine coolant and the transmission fluid line is run inside the radiator as well. The radiator cools both the engine coolant and the transmission fluid and the cooled transmission fluid exits the radiator and runs back to the transmission. I think the problem you have is that there is a break in the line that is running through the radiator and engine coolant has found a way to enter the transmission fluid line or vice versa.

You will want to replace your radiator. You may be able to find one at a salvage yard or worse case, need to have a dealer install a new radiator.

After your system is up and running again, you can add a cooler for your transmission. I have attached links to a couple of helpful articles about transmission coolers you can check out and I also attached a link to our transmission cooler product page.

I have attached a drawing that shows the best location for a cooler. You may find that a cooler like part # D13503 will work well for the Cadillac. This is a Class lll cooler that measures 11 x 8-3/4 x 7/8 inches. When installing the cooler you will also need a hose fitting, part # D13035.

expert reply by: Jeffrey L