2000 Malibu Coolant Loss

[Fishinguy40]

My wife has a 2000 Malibu that is losing coolant. I replaced the lower intake gasket about a year ago because it was leaking coolant. I used the Felpro kit and it seemed to work good.

One day in February I noticed a green puddle under the car. (I changed the Dexcool out a long time ago and went to the green stuff). It was obvious that the cap on the expansion tank was releasing coolant as it was wet on the frame below the overflow hose. I replaced both the thermostat and the cap on the expansion tank. When I did that it seemed like the threads on the tank are stripped. Though I was able to get the cap tight. The other night my daughter was driving the car and she came home and said it was running hot. One of her friends checked and there was no coolant in the expansion tank. I inspected everything. There is no evidence of an external leak any place. There is no evidence of coolant in the oil. There did appear to be some but not a lot of moisture under the overflow hose again. I suspect that even though I am able to screw the cap on tight to the expansion tank it is not holding pressure and I am slowly losing coolant this way. I plan to buy a new tank but was wondering if anybody has any other ideas.

[Big Buck Buster]

Head gaskets out? Get a cylinder leak test done to verify that the cylinders/valves are good.

If you don't want to bring it in to have that tested, I would fill the coolant back up again. Make sure that all the air is out of it. Use the bleeder screw(s), if it has them. Run it until it gets to normal operating temp with the cap off. They make a tool/product to test for combustion gases in the coolant. I call it the sniffer, because it pulls the air out of the expansion tank to test. You might be able to find it at your local parts store.

[Jeremy airjer W]

Something tells me Triple B on on the right track.

[Fishinguy40]

They make a tool/product to test for combustion gases in the coolant. I call it the sniffer, because it pulls the air out of the expansion tank to test.

What gasses are you looking for? CO? O2? I ask because I have access to instruments at work that will draw, sample and measure CO and O2 concentrations.

[Big Buck Buster]

Originally Posted By: Big Buck Buster

They make a tool/product to test for combustion gases in the coolant. I call it the sniffer, because it pulls the air out of the expansion tank to test.

What gasses are you looking for? CO? O2? I ask because I have access to instruments at work that will draw, sample and measure CO and O2 concentrations.

You are looking for exhaust gases(hydrocarbons) that would enter the cooling system from the cylinder. The sniffer that I am talking about will change color if the exhaust gases are present.

[Scott K]

Originally Posted By: Big Buck Buster

They make a tool/product to test for combustion gases in the coolant. I call it the sniffer, because it pulls the air out of the expansion tank to test.

What gasses are you looking for? CO? O2? I ask because I have access to instruments at work that will draw, sample and measure CO and O2 concentrations.

If you have a 4 gas analyzer, that will work, if not, the local parts store sells kits with the fluid.