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2003 Deville - cooling system problems

3834 Views 34 Replies 5 Participants Last post by  20grand
I have to do this on my Deville in the AM. It drives and rides nice but after a while at idle the gauge will increase and cold air kicks through the vents. After I rev the rpms real high, the gauge comes back down and then I have heat. I also checked the tank and she's nice and full. Was thinking maybe a faulty thermostat but will check the lines before I pull that out.
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Never got much into golf besides a put put and a really cool range in Chelsea.

As far as the air pocket goes, could there be several runs to get the air out? Should I rev it once it gets hot to bring the gauge back down or park it when it gets hot?
Just drive it normally and check it in a few days.
You either STILL have air in the system, or ARE PUTTING air in the system.
Hey fellas. Looks like it's all good. Drove it all day today and the gauge went up just two notches for a couple of seconds. I added just a little more antifreeze earlier and so far the heat blows hot and the gauge is where it's supposed to be. Fingers crossed.

Thanks for all of the input.
Spoke too soon. After a couple of errands, the temp gauge went all the way to the top. Not sure wth is going on, but it's past annoying. No coolant spilling out either.
It maxed out? If the water pump is spinning and the purge line is clear, it's time for a block test.
Maxed out. On the side of the road now. Purge line is clear. Wouldn't the water pump be turning if the belt is turning? I did a block test on it and the sob stayed blue. I did it twice.
If you can see the pump pulley turning, it's doing its job.

Did you do the block test after an overheat?
No. Waited until the gauge went to the halfway mark.
I don't think so. It was just a random check after I let it warm up. I still have a block test at home. I'll give it a shot tonight once I make it home and let you know.


Didn't have enough fluid tester but noticed that the coolant levels are still good. I e never had to put any coolant in this car.

My first head gasket overheated right away and the other Deville that I have loses coolant. I've even seen coolant shoot to the moon. This one is a bit weird but it just maybe a HG. I don't know what else it would be. Water pumps going, new thermostat, plenty of good coolant, bottom radiator hose is cool and the top is nice and hot.
Do the block test again as soon as possible after the overheat episode. Sure sounds like you are putting exhaust gases in the cooling system. Probably in the early stages.
So I went and tested both of the radiator caps that I had for the Deville, and both failed. Got a new one, drove it and it and didn't overheat once. I'll keep driving it and keep you guys updated.
Amazing what something as simple as a surge tank cap can put you through. It's always the last thing you think of and check. Good luck and keep us posted. Inquiring minds want to know.
I have a 2000 or 2001, can't remember which year, but it has two hard coolant lines that run across the top of the motor parallel to each other. One gets hot and the other one does not. The one that gets hot, runs to the reservoir, which is the line that I believe is closest to the firewall. The one closest to the radiator is the cold line. I figure this is NOT normal. Am I correct?
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