Heater Question

sixstringsteve

sixstringsteve

Well-Known Member
Location
UT
My 1981 pickup's heater isn't very hot. I pulled the heater core and flushed it and replaced it. I'm getting a little bit of heat, but not much.

I'm guessing I have air pockets in my heater/coolant lines.

The engine does not overheat at all, it doesn't even get past the 50% mark on the temp gauge. T-stat is working. I'm guessing I either have a bad valve (the one that allows coolant to flow to the heater core), or I have a few air pockets in the line.

What are you thoughts? How do I get rid of the air pockets in the heater line?
 
Check to make sure when you flip the lever from cold to hot that it actually moves the arm on the heater box. I'm not familiar with the 80's Toyota but most trucks I have seen have the lever on the right side. I even had a truck that the lever wouldn't stay connected and I just moved the arm manually on the heater box.
 
yeah, I've traced the cable back to the engine bay, and it is moving the little lever on the heater valve. But I haven't pulled it apart to verify that the valve is actually opening.
 
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I believe there is also a flap that opens/closes in the box that the heater core sits in. Both the valve and the flap should move with the lever on the dash. You could tell if the valve is allowing hot coolant through by feeling it (if you can access both sides of the valve or feel the return line on the heater core).
 
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Here's the control pieces on the bottom of my Tacoma heat box that control heat. When you move the lever the white pieces move which basically opens or closes the flap to allow hot air through. (81 truck could be quite different but the concept should be similar)
 

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it's pretty different on the 81. The problem isn't airflow, it's the problem of hot coolant getting to the heater core.
 
First thing you want to do is warm up the motor, touch both heater core water lines. If both are hot then your heater core is hot. If you fan works and your heater core is hot then it is the flapper door deal. If your heater core lines aren't heating up, check your t-stat. Maybe you need a hotter one.
 
Also, if your heater lines are hot, it could be your heater core is not isolated. The fan will pull cold air around the edges of it if you don't have it sealed right.
 
Its an early toyota... get used to it.
out of the 4 toyotas I have been in, non of them has a warm heater, on Pirate they said to back flush your heater core, i have never done it.
 
Like has been said before, you need to check the temp of the lines going in and out of the core. The hot air from the heater will never be as hot as these lines. Any chance there is an aftermarket ball valve shutting off flow? If the blend door is not operating fully or doesn't seal you will mix hot and cold air. Just looking to see if the cable is moving fully doesn't mean a lot. By now there will be enough slop in the line to keep the door moving all the way to heat if there is a small blockage such as the foam seal around the door falling off.
As far as old Yotas not blowing hot..... I've rebuilt them and know they can put out the heat.
 
I'll check the temp of the lines, I"m guessing that's my culprit. The cable moves the valve it's connected to, I'm just not sure if the actual valve is plugged or not. I'm still guessing i've got air in my line.
 
I'm sure the core is fine, I don't think aftermarket heater like a mojave would fix the problem. I'm 99% sure the core isn't getting hot water to it. I'll check it soon. Thanks for the help everyone.
 
Spork said:
I believe there is also a flap that opens/closes in the box that the heater core sits in. Both the valve and the flap should move with the lever on the dash. You could tell if the valve is allowing hot coolant through by feeling it (if you can access both sides of the valve or feel the return line on the heater core).
Click to expand...

I was wrong Spork, I apologize. You hit the nail on the head. Now that I close the box the heater sits in, the truck gets toasty warm in 5 min! It was so hot that I had to turn it down. Thanks everyone!

Hey, 2000th post. I must have a problem.
 
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