2000 Chevy Cavalier Coolant Leak No One Can Find

Reader Question I have a questions about my 2000 Chevy Cavalier. My coolant is leaking (takes about 2 months before the coolant light comes on). So far I have had the hoses replaced (mechanic #1) and a new thermosat put in (mechanic #2). The most recent mechanic (#3) said that it could be a head gasket but he wasn’t positive, it was a guess.

That’s a big $$$ replacement for a guess. He had it under pressure for about 6 hours, but couldn’t find the leak. I know it is leaking because the coolant light comes on, the temp goes up, and of course I can see that it is low and that the fluid is on my driveway.

No one can seem to fix my car. Have you heard this problem before? Do you have any other ideas? My insurance quote is attached…thanks!

Hi there,

I think you need to see ONE MORE mechanic..one is a little more qualified than the others. It does sound like you have an EXTERNAL coolant leak somewhere…radiator, water pump, intake manifold etc. etc. but probably NOT a head gasket problem. You said you can see coolant on the driveway…so this SHOULD be an external leak, and your mechanic SHOULD be able to see this leak with a cooling system pressure tester.

I would go to another repair shop…or the dealership and get them to pressure test your cooling system again, tell them this is a slow leak and they might want to keep pressure on the system for the day or overnight to locate the leak.

I have seen a few leaky water pumps that would not leak during a normal cooling system pressure test for hours but would begin to leak as the engine was running. You usually perform a cooling system pressure test with the engine off…so a leaky water pump might go undetected.

Keep adding the green or orange coolant to the radiator so it will be easier for you to see the leak yourself. I would open the hood and stick my head under the vehicle next time you see the coolant on the driveway.

There must be some kind of tell tale sign or trace of the leak somewhere under the vehicle. The water pump you can not see, so you will only see a few drops coming out of the engine area around the fan belts.

The plastic overflow bottles are notorious for leaking as well, so look around the bottom and back side of the plastic bottle and have your mechanic test the radiator cap as well since they too can also leak.

If you had a head gasket leak I would expect to see water in the engine oil, and it would look like a chocolate milkshake, you would have an engine miss due to water getting on the tip of the spark plug, and you would have lots of white steam/smoke coming from the tailpipe and your check engine light would most likely be on as well since the engine would be running poorly.

Thanks for getting the insurance quote…hope that helps you save money

Austin Davis

Posted in: Fluid Leaks

2 Comments on "2000 Chevy Cavalier Coolant Leak No One Can Find"

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  1. Al says:

    GM’s bright idea of a plastic outlet housing sealed by just an o-ring… FAIL.

    The housing sits underneath just off to the side of the power steering pump on the driver’s side of the engine. Anyone can replace it with normal hand tools, but prepare yourself with a lot of aggravation because it’s in a tight area. If this stupid plastic housing was metallic…and…a normal type of material gasket was used, this problem would not be a problem. Regardless, I’m glad it wasn’t the water pump because I’d blow up the car and be done with it.

  2. Scott Nearing says:

    I am working on a 2000 Chevy Cavalier 2.4 l for this same ‘mystery’ coolant leak scenario. It seems that the coolant outlet flange one the top driver side of the engine is known to fail. The flow from the leak is spotted on the ground, coming from just off center on the driver side near the firewall. Looking up, with the vehicle on jack stands, I see the water traveling from near the location of the heater hoses but can not see the source. I pulled all the sensor connectors near the flange, pushed the loom out of the way; this revealed the coolant was flowing from under the flange. No doubt the section of the flange that inserts into the orifice is crumbling and allowing the coolant to flow out.

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