No heat after head gasket replacement

beewstew · Post by **beewstew** » 03 Apr 2025, 06:04

I finished a head gasket replacement a few weeks ago and in so doing replaced the coolant. New thermostat. Added coolant via the expansion tank, also added some bars leaks because initially there were a few drips from the system.

Tried running the car for a half an hour with the expansion tank cap off. Adding coolant every 5 minutes or so when it would go down. Do I have to do that for a few more hours?

Car shows no sign of overheating. Temperature needle is straight up and down. Oil is still oil, no chocolate milk.

It's been about 150 miles since I did the repair and there's still no heat from the climate control system. If there's some kind of air bubble or clog in the heater core, how do I get it out?

Or is there some kind of mixing valve that's stuck closed somewhere?

Post by **jonesg** » 03 Apr 2025, 07:31

thermostat upside down,
thermostat air bleed hole at the bottom instead of the top.
or flap doors in the cabin.
Grab the coolant pipes where they enter and exit the firewall.... both should be hot.

Post by **cn90** » 03 Apr 2025, 08:04

Bar Leaks should never be used.
It is likely the cause behind this.

Post by **vtl** » 03 Apr 2025, 10:10

What cn90 said. You are up for a heater core replacement. Behr/Mahle is the good one. If you can find one. Nissens and everything else is worse.

beewstew · Post by **beewstew** » 03 Apr 2025, 15:40

vtl wrote: ↑03 Apr 2025, 10:10 What cn90 said. You are up for a heater core replacement. Behr/Mahle is the good one. If you can find one. Nissens and everything else is worse.

Appreciate the suggestion. Can I flush the core while it is still in place? Thinking of holding a garden house up to where the hoses connect at the firewall.

Post by **vtl** » 03 Apr 2025, 15:56

beewstew wrote: ↑03 Apr 2025, 15:40 Appreciate the suggestion. Can I flush the core while it is still in place? Thinking of holding a garden house up to where the hoses connect at the firewall.

Yes

beewstew · Post by **beewstew** » 03 Apr 2025, 18:32

vtl wrote: ↑03 Apr 2025, 15:56
beewstew wrote: ↑03 Apr 2025, 15:40 Appreciate the suggestion. Can I flush the core while it is still in place? Thinking of holding a garden house up to where the hoses connect at the firewall.
Yes

Perfect, thanks for the suggestion. I flushed the heater core at the firewall with the garden hose and that seems to have cleared the clog out of the heater core. Heat now seems to work. Had to alternate a half a dozen times between the two nozzles before the water ran consistently clear.