2002 Aurora 4.0 Coolant leak but engine is cool

[lisa]

I am a 65 year old woman who knows very little about cars. I have a 2002 Aurora 4.0 that I bought in 2014. I love this car and have had many repairs done including the head gasket 3 years ago. There has been minimal mileage since then due to Covid. Last summer on a hot day and after sitting in traffic I received the DIC message to turn off air conditioning as engine may overheat. I turned on the heat and pulled over. The gauge indicated we were slightly over normal but not anywhere near red zone. The car was parked until the gauge showed it was below normal snd driven a block home and parked. Over the next months the car was started but with no clues or messages displayed.Had it towed to be checked and they found the coolant level only slightly low and no signs evident of where the coolant leak would be. After two weeks they put GM tabs in the coolant system and sent it home to drive for further symptoms when I was not pleased with taking apart the engine again. Since then it starts and drives okay for about 15 minutes in residential area before my cabin heat seems to go from hot to cool and eventually disappear. At that time I notice my temp gauge mar rise very slightly or not. I park the car. My coolant overflow tank and the top hose to radiator are hot to touch but my engine is cool to touch? Recently I notice a leak dripping under the engine frame in the middle that I believe to be coolant and have a few times DIC Low engine coolant message although upon checking the level is up to the neck or more of the overflow tank. ( The overflow tank has been replaced in last few years as well as the water pump) I also notice that no matter when I take off my rad coolant cap it is super pressurized and makes a large hiss even if the car is cold overnight in - 30C. (Winter inCanada) I have considered the problem lies within the rad or thermostat or even the rad cap to now considering the throttle body. The car has 228,000 km mileage with minimal incurred since the head gasket repair. I would greatly appreciate any help. I have followed your comments for many years and hope you can point me in the right direction. Thanks.

[Marc]

My guess.....The thermostat is the first item to look at.

[Paulaurora]

or might be clogged heater core . I would pressure test the system. I had something like that as well and for me it was small invisible to the eye crack on already changed coolant tank where the coolant would go out under pressure. That's when do pressure test of the system reviled the problem. another common issue cross over gaskets.

[AUROD X]

I recall that job. Yes for me after checking, also replacing anything to do with Coolant and still had that Tiny Drip at the Bottom End of the Engine. That's when I knew I had to go Deeper, and sure enough it was the WATER PUMP HOUSING GASKETS 😖😢. What a Nightmare 🤦, so after replacing Gaskets, thank God no more Coolant Leaks.😃😎 Ran like a Champ, probably gain Huge Horsepower...🤔😂🤣

[Paulaurora]

Mar 6, 2022 13:13:23 GMT -6 AUROD X said:

I recall that job. Yes for me after checking, also replacing anything to do with Coolant and still had that Tiny Drip at the Bottom End of the Engine. That's when I knew I had to go Deeper, and sure enough it was the WATER PUMP HOUSING GASKETS 😖😢. What a Nightmare 🤦, so after replacing Gaskets, thank God no more Coolant Leaks.😃😎 Ran like a Champ, probably gain Huge Horsepower...🤔😂🤣

yep that can be as well.

[AmunRoo]

My initial thought could be that you have a leak from the water pump housing. If it's toward the middle of the car it would make sense. Could be that you have a bad water pump that led to the leak. If you're cool and think this pressurized even when the car is cold, this can also signify that the head gasket problem has once again returned. They can run a test for exhaust gases in the reservoir tank to see if it's exhaust that's pressurizing the reservoir. Hopefully you don't have to have another teardown. These cars are difficult when it comes to head gasket repairs because the block is made of aluminum. Trusting that they did the job correctly, they didn't have to retap any of the holes for the bolts. I guess I would start with testing the coolant reservoir tank for exhaust gases. Then a pressure test. Finally I would try to clean off as much as I could on the bottom using brake clean or some other type of cleaner and then looking for the leak.