Heater Valve Causing Overheating?

[Hltoppr]

Ok, 1994 FZJ80,

Skeddy and I replaced his valve cover gasket last friday, and we had to remove the heater valve from the firewall at the rear of the cover. When we went to put it back on the adjusting wire had come loose.

This morning, while driving up from Phoenix, Skeddy noticed the engine starting to overheat, pulled over and the wire had once again come loose. Replaced.

The engine has been overheating off and on since then this morning...

What the heck does this valve control, and is there any adjustment to it?

-H-

 

[turbocruiser]

If i read you right, that valve simply opens or shuts or opens or shuts partially to allow coolant to flow through the heater core or heater cores. This makes the heater cores as hot as the coolant, then through the fans the heat is pushed out of the cores and in to the vehicle. I might be missing the message you made but basically by removing that valve technically nothing should have screwed up so as to make the motor overheat. As strange as it sounds, it sounds like coincidence??? Think of it this way, unless you NEED to regularly run the heater to keep the vehicle from overheating, and unless you accidentally shut the heater off regardless of where the switch inside is set, then nothing you did should have started this trouble. Still, i'm intrigued by this. If in fact you NEED to regularly run the heater to keep the vehicle from overheating, then something else is seriously screwed up ( headgasket ) and perhaps somehow you pulled this bandaid from the skin and now you see the real wound. I started to wonder if what happened is some internal cooling system air lock ... did you actually remove the valve by disconnecting the heater lines or did you just remove it from the firewall and let some slack set it back enough to get the valve cover on and off??? This would help solve the mystery, but again, technically speaking, whether that valve is open or closed you should not overheat. HTH. Write back, this is interesting.

 

[snowwolfwarrior]

By what you discribe, if you did take the valve out, are you sure you got all the air out of the water system, sounds like an air lock, run the engine from cold and take rad cap off and keep topping up and squeezing all the hoses to make air come out.

 

[turbocruiser]

By what you discribe, if you did take the valve out, are you sure you got all the air out of the water system, sounds like an air lock, run the engine from cold and take rad cap off and keep topping up and squeezing all the hoses to make air come out.

Yes, this is sorta what i was thinking. The strange thing is that if the air lock was in the heater cores it should still not affect the motor, and, as long as there was enough extra coolant in the coolant overflow tank to replace whatever may be lost from removing the heater core valve, the air lock in the motor should quickly work its way out. It would be wonderful if this is all it is, even more wonderful if the reason for the temp spike was really only the temp sensor reading a dry hot spot that did not truly translate to an overheating situation. Still, I'm thinking something is wrong with the rad cap, and/or, the rad hoses, and/or there was more coolant lost than the overflow tank offers. HTH.

 

[skeddy]

you guys were right. more coolant was lost than the overflow showed and yes there was a lot of air in the system. after filling the radiator and purging some a ir. mo problems! thanks for the help.

 

[turbocruiser]

you guys were right. more coolant was lost than the overflow showed and yes there was a lot of air in the system. after filling the radiator and purging some a ir. mo problems! thanks for the help.

Cool, well, actually, HOT DAMN, if you are lucky, those three temp spikes you saw were just as the air pockets moved past the sensor, if not, the coolant was so low that those temp spikes actually were what the engine was running with! Did the needle spike up AND down rapidly or did it climb fast and stay there???