How to check for bad heah gasket on 07 Equinox. had my mechanic check engine after losing heat, heat did return after 30 minutes and still working fine the next day, however mechanic told me i had a bad headgasket.

ole

 

One thing to look for is white smoke from the exhaust - this could occur only at startup or continuously depending on the severity of the leak. Don’t let steam fool you, which is normal - the difference between steam and white smoke is the steam will dissipate almost immediately once it exits the tail pipe - smoke, on the other hand, will remain in a cloud formation for at least a few seconds.

You could also check the compression of each cylinder - one or two cylinders with a low reading relative to the others indicates a leak. Generally accepted numbers are 100 PSI minimum with no more than 10% difference between the highest and lowest reading (divide lowest number by the highest number - any result less than 0.90 is too high a difference).

There’s also a test kit available from Lisle tools ( ) that checks for the presence of exhaust gases in the cooling system - I’m not saying it’s a completely fool proof method of testing, but I’ve checked several vehicles with it and have had dependable results.

 

Thank you Gumby22
I had some time today to check out the equinox. It starts up quickly and idles smoothly. let it run for about 45mins and other then exhaust vapour no white smoke, we are getting heat, we did see liquid leaking from pasenger side of muffler however could not tell if it is coolant or water. No coolant in engine oil. Its has only lost heat on 2 occasions and on the 1st mechanic bled system and checked for bad head gasket and told us head gasket was good. 2nd time was 30 days later and heat retuned within 20 mins on its own however mechanic told us we had a bad head gasket. Did replace coolant over flow cap with new, old cap was very hard to remove.

 

It’s completely normal for water to drain from the muffler. Water is a by-product of the Catalytic converters doing their job, so most mufflers these days have a hole drilled in one end to allow the water to drain and prevent rusting them out.

Does the transmission cooler also utilize the radiator? I can’t recall if it shares the radiator or AC condenser, so if it does use the radiator, check the ATF to see if it’s milky in color.

If it’s only lost heat twice and about a month apart, Determining the reason could prove difficult, and I’d advise taking any diagnosis for major repair (head or block related) with a grain of salt until there’s sufficient evidence to support it. Fortunately there’s things you can do to help narrow it down so you don’t have to pay a shop for extensive diagnosis.

1) Check the coolant level once per week - and just to be clear, the level is best checked after the car has sat overnight and had plenty of time to cool down - and keep track of how much coolant it’s using per month.

2) Note the conditions present next time it loses heat, such as:
-engine and vehicle speed (idle vs. acceleration, town vs. highway, etc)
-engine temp (doesn’t need to be exact - just note position of gauge needle)
-ambient temperature
-blower motor speed
-temperature blend setting
-Mode setting (AC is automatically utilized for defrost, so having the AC engaged could make a difference)

3) By feel, check the temperatures of the heater core inlet and outlet hoses next time it loses heat. The inlet should be hotter than the outlet, but both hoses should be warm. A warm or hot inlet and a cold outlet indicates the heater core is plugged. Both hoses being warm but still no heat in the cabin indicates a malfunction with the temperature blend door actuator. Both hoses being cold indicates air in the system.

4) Thoroughly wash the engine and engine bay using hot water and low pressure to monitor for external leaks. Park in a garage or on a clean slab of concrete to check for wet spots before driving.