No heat, bad thermostat? but the gauge is fine. Options

[czwalga]

Alright the Temp gauge moves to middle of the gauge after the car heats up. However I still have no or minimal heat.

I obviously though that the heater core is clogged. Nope, I was able to run a pretty good stream of water through it with really no resistance. The valve is working and is open.


The only thing I can think of is that the temp gauge is 'wrong', and the thermostat is stuck open. It's a 3sge, and I did a lot of wire/dash ripping, but I dont think that has anythin to do with it. Removed the AC core, but I built ducting from the blower after I relocated it. Air is blowing out of the vents. Its my understanding that all the air passes through the heater core to the front vents no matter what. The heat is controlled by the valve in the engine bay.

[Batman722]

Bleed the system and change the t-stat.

[Galcobar]

If the sixth-gen's 5SFE isn't too radically different from the fifth-gen in this regard, look for the blue cable running through the firewall, almost in the centre of the engine bay. Make sure it's moving when you adjust your temperature.

[czwalga]

Yeah I've took that off and made sure its working fine it is. It's not the thermostat changed it no difference.


I'm going to put CLR in the heatercore.... even though it was able to pass water its still the only thing that makes any kind of sense to me at this point. Unless the water pump is dieing, but I dont think so.

[advancetoyota]

i feel ya on that one.. im having the same problem

[vile_v]

Same issue happened to me after I changed my waterpump. I thought it was a faulty thermostat at first but it turns out that it had an air bubble. The trick is to bleed the car while having the front jacked up as high as you can. This causes the air in your coolant system to rush to the top much faster than being on a flat surface. I hope that helps!

[czwalga]

It's no air bubble. Not the thermostat... probably going to pull the core.

[Bitter]

CLR eats aluminum.

[czwalga]

CLR eats aluminum.

Yeah, you can't leave it in too long.

[Cuts_the_Pilot]

So the gauge reads normal but the air from the heater when on hot is still cold? Is it cold or just luke warm?

Was the blown air hot before you did the dash ripping and A/C core delete?

Assuming the engine is actually at operating temperature the only things you can deduce is:

The core is blocked (proved not to be the case).
The core is clogged (you are checking this now).
Something you did when you pulled the dash apart has changed.
Coolant is not actually getting to the heater itself (or is only getting there with a small flow and not enough to heat up the core), perhaps the heater hoses to the tap or the coolant hoses or metal coolant pipes on the engine are blocked.

[richee3]

I have had to swap engines a few times now, regrettably. It seems like this is an issue I have each time a new motor goes in the car and I have to add coolant again. However, if I leave it running and the heater on long enough, eventually I get heat. I don't understand why that is, but it just seems to work like that. Even after the thermostat has opened and I've burped the coolant system, I still don't have heat for a while but it always comes back. Maybe it's the same issue?

[Bitter]

probably still have air in the system.

[Cuts_the_Pilot]

Mine has the same issue as richee3, it takes ages for the air to come out hot, I just put that down to a semi blocked heater core and I'm putting off fixing it (since its summer here anyway and the days are hot) until I need to drain the coolant again.

[njccmd2002]

put the car in your shoulder pat it on the back to make it burp!!!!

[czwalga]

It's not air.... The car was driven for 4 months without coolant level dropping. I also filled the heater core with water via a hose seperately via a hose, still nothing.

I pulled the core out and filled it with clr. Hooked the heater core back up to the system in the engine bay. For the first time the return hose got hot. I'll put it back in, the next few days but i'm confident I'll get heat now.


I thought that running water through it proved it wasnt clogged, but i dunno i think a lot of it was clogged.

[richee3]

I think mine is caused by the time it takes to burp the system. After the first time it gets heat with a new motor, it works perfectly. Just takes 15-20 minutes the first time. I thought maybe it was something similar.

Glad you got it lined out!

[czwalga]

It's fixed. I had a double wammy. The heater core was clogged, but when I unclogged it, still didnt work. Turned out the motor on the heater vent control thing died as well. So once I unclogged it the blades werent moving to move air across the core.