Heat stopped working

[deercoker]

air in system maybe?

 

[cucvrus]

I think you need to pressure check the cooling system cold. See if it can hold 15 PSI. I suspect a head gasket leaking. Does it have coolant in the over flow? And if so does it seem to have more in the over flow after a 25-30 mile drive? Check that and report back.

 

[deercoker]

I checked the over flow this morning and it was at the cold mark, I drove it 30 miles and after 5 miles the heat was lukewarm and stayed that way till I got home, I checked the overflow again while hot and it was about 2 inches above the cold mark. This is the 3rd M1009 I have owned and I don't think the other 2 had hot heat so maybe it is just me, the outside temp is about 50 degrees and the heat seems to be just a little warmer than outside temp.

 

[cpf240]

The heater core could be plugged up, might try flushing it. Or, perhaps the PO replaced the heater core with an aftermarket one. Some of the aftermarket cores are thinner than the stock core, and unless installed properly, air can go around them, rather than through them.

 

[deercoker]

so does the level in the overflow tank after driving 30 miles 2" above cold level sound right?

 

[cucvrus]

Anything is possible. if it where mine I would remove the heater box entirely and double check all the flap seals which are gone I am sure. And check all the duct work and make sure 1/2 the blades on the squirrel cage fan are not chewed thru or just plan disintegrated. Also pressure test the cooling system. I have changed several sets of rusted thru head gaskets in the last year. Heat loss inside the cab was the first symptom. I hope not yours. but not a bad PM to do on a 30+ year old vehicle. Good Luck.

 

[deercoker]

I will have someone pressure test the cooling system, I can't see changing a head gasket unless bad, one would think a blown head gasket would also have other symptoms as well, Thanks cucvrus

 

[cucvrus]

Sorry to say it does not. I drove one 4-5 years with a bad head gasket. Heat loss was the first symptom, over pressurized cooling system was the next and then steam from the left side tail pipe in damp rainy weather was the final and last thing before I removed the head gasket and had the heads redone. The original head gaskets were/are tin and rusted thru at the water ports and that lead to the combustion chamber. I seen it on several engines in the past couple years. Good running engines. I hope this is not the case. But I think it is something to keep in mind for the long haul. Good PM. Take care.

 

[deercoker]

So no coolant loss? if it is burned burned off in the combustion chamber it is not replaced right? I am not nearly as knowledgeable as you about the head gasket situation but I would imagine coolant loss at some point, not arguing just trying to understand! I think the easiest first is the thermostat check then the duct work, Thanks cucvrus

 

[cucvrus]

I agree. Check everything. that is why I ask if you had a thermometer. Good Luck. But putting head gaskets on is not all that bad.

 

[deercoker]

Changed the thermostat to the 22 dollar one from napa and found that it had the same one in (hockey puck type) but the plastic puck was stuck at an angle so it was not working, it got dark so did not have time to look at it further to check manufacturer but long story short, ran it with cap off to relieve any air and topped off coolant, drove about 2-3 miles on way home and had hot heat for a cucv so hopefully that was the heat problem, now I have to fix all the other little things that are bad, thanks to all for the help.