2007 Vibe sudden lack of heat

[KGMtech]

Unless you have a unique car with a 12 ounce cooling capacity, 4 ounces low is not the reason for no heat.

 

[Warstud]

Could be due for a new water pump

 

[ekrampitzjr]

They are known for bad WP seals on the 1.8, the SLLC pink coolant seems to seep out of them (my mom’s ‘06 Matrix does), but it would have to get pretty low to start air locking the heater core. Throw a new quality radiator cap on it too, the xB in my sig lost coolant due to evaporation due to a leaky one. Or rent-a-tool a combustion gas coolant tester & get ready for a head gasket replacement…

This, unfortunately. In a sealed system filled properly, coolant levels should not go down significantly over time. Loss of coolant is a sign of something bad.

 

[nthach]

I would suspect a leak in the cooling system for the sudden coolant loss. Low coolant doesn’t mean loss of heat unless it’s too low.

Look at the WP/t-stat first. You have a 1ZZ-FE in that Matrix, the 2AR-FE(and the 2AR-FXE) is a known head gasket eater(in Prius/CT200h form, but it’s the same block and head between regular and hybrid versions.

 

[zzyzzx]

Bad head gasket, you just don't know it yet.

Exhaust gas made it into your radiator and airlocked the heater core.

I've had a bad head gasket. Heat worked GREAT!!!

 

[wag123]

Bad radiator cap (or another cooling system leak). If the cooling system doesn't pressurize the heater won't work. I would pressure test the cooling system and replace the radiator cap.

 

[bullwinkle]

I've had a bad head gasket. Heat worked GREAT!!!

It gets bad enough, it works a little TOO well-like shooting coolant steam out of the overflow tank well!

 

[philipp10]

Unless you have a unique car with a 12 ounce cooling capacity, 4 ounces low is not the reason for no heat.

Actually I still believe it was just the lack of 4 ounces. Here is the way I see it. The top of the heater core is the highest part of the cooling system. The heater core only holds about 10 ounces of fluid. Therefore a 4 ounce bubble of air, if all in the top of the heater core is a significant amount of the heating capacity that is lost. When the coolant was low, it had SOME heat, just not as good as it should have. Adding the 4 ounces displaced the air pocket and viola, the heat was back.