# Boiling Coolant **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [October 12, 2008, 3:47am UTC](https://community.cartalk.com/t/boiling-coolant/20632 "2008-10-12T03:47:33Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![AJZier](https://avatars.discourse-cdn.com/v4/letter/a/dc4da7/32.png) [@AJZier](https://community.cartalk.com/u/AJZier)\ **Post date:** [October 12, 2008, 3:47am UTC](https://community.cartalk.com/t/boiling-coolant/20632/1 "2008-10-12T03:47:33Z")
My daughter has a 2002 Chevy Malibu. Not all the time, but at random times, the coolant in the overflow tank boils. I have replaced the thermostat. It does not seem to be overheating when this happens. Any ideas? ---
**Author:** ![hellokit](https://avatars.discourse-cdn.com/v4/letter/h/6a8cbe/32.png) [@hellokit](https://community.cartalk.com/u/hellokit)\ **Post date:** [October 12, 2008, 4:04am UTC](https://community.cartalk.com/t/boiling-coolant/20632/2 "2008-10-12T04:04:14Z")
There might be some debris (rust scale, etc) floating around in the coolant. Every so often it gets lodged in a radiator tube and impedes the flow of coolant. [Plausible theory, huh?]. Drain the coolant. Use a garden hose to flush the cooling system. Refill with your favorite brand. I hope this work because the theory of quantum cooling states isn’t well understood. ---
**Author:** ![galant](https://avatars.discourse-cdn.com/v4/letter/g/77aa72/32.png) [@galant](https://community.cartalk.com/u/galant)\ **Post date:** [October 12, 2008, 4:51am UTC](https://community.cartalk.com/t/boiling-coolant/20632/3 "2008-10-12T04:51:13Z")
These are notorious for intake gasket leaks. I am not sure if that is your problem, but I will check that before any engine damage happens. ---
**Author:** ![pleasedodgevan](https://avatars.discourse-cdn.com/v4/letter/p/51bf81/32.png) [@pleasedodgevan](https://community.cartalk.com/u/pleasedodgevan)\ **Post date:** [October 12, 2008, 5:11am UTC](https://community.cartalk.com/t/boiling-coolant/20632/4 "2008-10-12T05:11:09Z")
There may be nothing wrong. When the engine is running and is not fully warmed up, some expansion takes place and could make it seem like the coolant is boiling. The coolant is constantly expanding and contracting if the fan and thermostat are working right. ---
**Author:** ![Cougar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cougar/32/21348_2.png) [@Cougar](https://community.cartalk.com/u/Cougar)\ **Post date:** [October 12, 2008, 12:56pm UTC](https://community.cartalk.com/t/boiling-coolant/20632/5 "2008-10-12T12:56:28Z")
I tend to think that Galant may be correct about the headgasket theory. I would have a block check done to see if there are exhaust gases in the coolant. ---
**Author:** ![Docnick](https://avatars.discourse-cdn.com/v4/letter/d/ecae2f/32.png) [@Docnick](https://community.cartalk.com/u/Docnick)\ **Post date:** [October 12, 2008, 3:09pm UTC](https://community.cartalk.com/t/boiling-coolant/20632/6 "2008-10-12T15:09:34Z")
Agree, with a GM car of that age, always check for intake manifold gasket problems first. I had an oitherwise great Caprice, but when it developed problems the shop immediately identified the intake manifold gasket. ---
**Author:** ![Nickb2](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nickb2/32/5745_2.png) [@Nickb2](https://community.cartalk.com/u/Nickb2)\ **Post date:** [October 12, 2008, 3:38pm UTC](https://community.cartalk.com/t/boiling-coolant/20632/7 "2008-10-12T15:38:47Z")
If headgaskets were shot then the engine would probably pass combustion to coolant if blown on a coolant passage. But this usually causes overheating. But cyl combustion in coolant may apear to be coolant boiling. This is easily verified with compressed air in each cyl at TDC or as cougar said, verify exhuast gas in coolant at your local reputibal shop, if your blue test liqiud turns green you have a head problem. ---
**Author:** ![rrhoff](https://avatars.discourse-cdn.com/v4/letter/r/8e7dd6/32.png) [@rrhoff](https://community.cartalk.com/u/rrhoff)\ **Post date:** [October 12, 2008, 6:11pm UTC](https://community.cartalk.com/t/boiling-coolant/20632/8 "2008-10-12T18:11:49Z")
this model came from the factory with dex coolant.have you changed your antifreeze on this car.