Issue with coolant

Jessica Lopez-Rogina

Asked by Dec 27, 2014 at 05:34 PM about the 2005 Cadillac DeVille Base

Question type: Maintenance & Repair

I believe the water from the coolant
system is not flowing right because
I've noticed the water pressure is
building back into the coolant tank
and is building up pressure. Another
issue is the check engine soon light
appears and a green temperature light
appears as well but the car
temperature in the dash is where it
should be even though the engine is
hot. There are no leaks any where but
the water drains out when the car is
turned off. I checked the oil to make
sre no water is going into the engine
but it appears fine. Would could be
the cause of these issues? Will
changing the thermostat fux the

5 Answers


Need to find out where the coolant is leaking out. Low coolant level can cause these issues. Do pressure test on cooling system to find the leak. Small inspection mirror comes in handy while looking for the leak. If the weep hole on the water pump shows any signs of leaking replace water pump and therm.

1 out of 1 people think this is helpful.

Radiator cap or thermostat. If the cap can't hold sufficient pressure (about 15-16 lbs) then it is allowing coolant to flow into the overflow bottle needlessly. If you have a stuck thermostat it is allowing the car to run too hot, again causing coolant to expand and overflow into the reservoir bottle. Hopefully replacing one (or both) of those items fixes your problem, and it's not something serious like a gasket issue in the engine.

3 out of 3 people think this is helpful.

Pressure test the cooling system. You most likely have a blown head gasket. These Northstar engines are notorious for that. If that's what's going on you're looking at upwards of $3500 to fix it. The engine and transmission must come out, from the bottom of the car to pull the heads. There's also "buttons" that need to be installed to repair the head bolt holes in the block. HTH. -Jim

1 out of 1 people think this is helpful.

I've been fighting months on my DeVille with leak after leak and car overheating.firat thing mechanic told me WAS head gasket. I panicked. Before u panic when someone says must b gasket FIRST go to AutoZone, rent a tool that u put down in overflow, car running,add liquid u have to buy, ifs liquid turns yellow means YES u do have the head gasket issue But if the liquid stays blue u DO Not have a blown gasket. I did this test 4 times to make sure it kept giving same answer I have all problems that points to gasket Check that first It is 25.0 0 to rent that test apparatus take back full refund.just liquid u do have to buy


Regarding the thermostat issue yes if the thermostat is stuck or blocked that blocks water to flow through correctly

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