Cadillac CTS First Generation Forum - 2003 - 2007 Discussion, 03 CTS 84K miles oil cooler leak need help in Cadillac CTS Coupe, Sport Sedan and Sport Wagon Forums; I went thru this site and see a lot of talk about oil in the coolant..what I could not find ...
I went thru this site and see a lot of talk about oil in the coolant..what I could not find was a thread to repair your own oil cooler etc...I need pics and step by step if that is available on here...the dealer wanted $5600 and did not really want to touch it....I bought the wife a new STS and brought this one home..too nice of a car to give away for $1000 to a dealer...any way hope you guys can help....
do not drive it like that, you will blow the line off the rad, which is actually your transmission fluid.
there is a bunch of threads on this, you most likely need a new rad then to have the tranny lines attached and the tranny properly filled.
other option, which is what im switching to and i wish i would have thought of a year ago, is switch to a external cooler. there is some that have a ball bearing or something like that , it blocks the flow till the fluid reaches operating temp.
i dont know a brand off hand but someone else will jump in and tell you where to look.
did you see where it is leaking?
it is most likely the transmission oil... it is a oil cooler but for the transmission.
i am 90% sure the engine oil does not have a cooler....i just looked at the diagrams and i cant see any engine oil cooler.
hope this helps.
there is a internal oil cooler, looks like it is on the top of the engine inside.... most likely not what the dealership was referring to you having leaking.
the transmission oil cooler lines that go into the rad are one of the biggest problems on the cts..they leak and blow off.
someone else will jump in and verify.. but these diagrams may help you either way.
It is pushing the oil into the radiator and out of the pressure tank...it is oil for sure. I am hearing I need a new radiator, water pump, cooler, and all hoses relating to cooling....oil just destroyed them. The engine is fine, I do have a start issue with a sensor or starter, but that will have to wait. Where can I get a good service manual?
If its the lines going into the rad follow them back and you will see they connect to your transmission.
Transmission oil/fluid mixing with coolant is common when the line starts to leak, as well is it common for coolant to get in the transmission and ruin a perfectly fine tranny if not properly repaired and flushed out.
If you want the cooling system manual pm me your email address, the files are large but I will try to send them.
I suggust you call whoever told you about the leak and verify what they saw, and what oil it was..be specific and ask engine or transmission oil.
Also starting issues on the 3.2 usually point to the CPS (crank position sensor ) as the cause.
i've commented on these 'oil cooler' (oil and or coolant) leaks in the past a bunch of times - the saturn 3.0L engine, and the catera as well as the 3.2L CTS engines all seem to have the possibility for this problem
here's the illustration from my parts catalog (which shows a bit more)
what usually is leaking is the seals to the oil cooler #473 (banjo bolt metal seals) and #434 (the oil cooler seals) ... the cross-over seals #405 also seem to leak coolant and if you're going in there you might as well change them out as a precaution even if they're not leaking
we have seen a couple oil coolers that were actually leaking, but not very many - the cooler itself it a pretty pricey part
i don't think either of these leaks could get oil and coolant mixed though... it would have to be the head gasket to do that (i think)
Chris Heath (RippyPartsDept) is an ASE Certified GM Parts Consultant at
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I bought my 03 with chocolate milk shake throughout the cooling system. A dealer will not want to do this because of the process of cleaning out the cooling system. Here's what I recall that was important.
1) Next time, I would put the car up to access the cat/exhaust manifold bolts(driver side) (use extensions) and if worried about braking the stud (which are welded to the exhaust manifold), run the car to heat them , stop the car and break the bolts loose.
2) You will need the snapon tool for the fuel disconnect.
3) Doing the thermostat without accessing the timing belt is very hard. But, getting the oil cooler out with a crow bar was not easy.
4) Replace ALL the water hoses in the back of the engine.
5) Cut the hose off the heater. Twisting the hose can break the heater.
6) You will need lots of distilled water (I used reverse osmosis water) And, i used 3 large (gal) jugs of liquid cascade dishwasher detergent. About 4oz per treatment.
7) Dump fluid via large hose at the bottom of the radiator. With the big upper hose loose and the hose going into the throttle body loose, fill via reservoir. Connect each hose when it overflows. Keep filling reservoir.
8) Initially, heat up, let stand to cool a bit and drain. Leave this stuff in over night, not empty. To drive, you should do 1 or 2 heat/cool cycles filling up reservoir when cool.
9) Increase the time/miles when you are no longer dumping just sludge. Toward the end, drive the car 100 to 500 miles between treatments.
10) After ~2months, the brown, hydrated oil on the inside of the big hose on top of the radiator was gone.
11) I got a manual for my PC on ebay. It was very useful. Stuff like getting the air out of the fuel rail. LockTight the cooler bolts,...
12) I did get new, expensive rubber coated washers for the new cooler.
Good luck. You will fell like you earned your $5K savings.
I've checked the trans cooler lines and I have a small leak there. However, my coolant is still a nice pink color, and hasn't become chocolate milk just yet. I'm getting an external cooler and I'll have that on hopefully by tomorrow or Wednesday. I'm also going to install a PCV Oil catch can once that comes in. Hopefully that will be the last of this. I'm going to need a replacement for those trans cooler lines. Anyone have a part number for that?
And yes, I recognize this thread is about 10 days old. At least its not 3 years and its a valid question/comment. LOL