Need help troubleshooting a cooling system issue

Any progress on this? Having a similiar issue with my wife's GP.

No/little heat, temp rises, get heat for a few seconds, temp falls and blows cold. New thermostat, same issue. Bypassed heater core, same issue.
 
Axis said:
Any progress on this? Having a similiar issue with my wife's GP.

No/little heat, temp rises, get heat for a few seconds, temp falls and blows cold. New thermostat, same issue. Bypassed heater core, same issue.
Click to expand...
3400/3100 ?
 
Sorry for the delay, just worked on this again this morning. I flushed and filled the whole system then took the truck for a ride and it still ran cold with no heat. So I pulled the brand new Motorcraft thermostat that I installed last week and sure enough it was defective (thermostat was not seated in the plastic housing)....remember this is all one unit, so it was basically stuck open and allowing coolant to bypass the whole time. I compressed the spring and seated the thermostat then reinstalled it and topped off the fluid. Temp came right up, heat is hot in the cabin and no leaks so the problem is fixed.

Thanks again to moneypit for loaning me the vacuum refill kit.

--Joe
 
3100. Completely drained coolant & refilled with a vacuum kit today. I think I'm to the point I'll have to pull the new thermostat out and check it.
 
Axis said:
3100. Completely drained coolant & refilled with a vacuum kit today. I think I'm to the point I'll have to pull the new thermostat out and check it.
Click to expand...

I did head gaskets on my grandparents 92 3100.... It took FOREVER to purge. I had to jack it up and use the bleeder on the intake and have someone burp the throttle. I always turn the heat on, jack it up so the cap/fill hole is the highest point and squeeze the hoses while working the bleeder. Ill keep the bleeder open til it spurts then close it off til some pressure build then crack it open and itll force some air out. I think the key is to get the water pump moving coolant to force the bubbles in the core out. A vacuum bleeder is a great tool but they aren't always going to get all the air out right off the bat.
 
soap said:
Sorry for the delay, just worked on this again this morning. I flushed and filled the whole system then took the truck for a ride and it still ran cold with no heat. So I pulled the brand new Motorcraft thermostat that I installed last week and sure enough it was defective (thermostat was not seated in the plastic housing)....remember this is all one unit, so it was basically stuck open and allowing coolant to bypass the whole time. I compressed the spring and seated the thermostat then reinstalled it and topped off the fluid. Temp came right up, heat is hot in the cabin and no leaks so the problem is fixed.

Thanks again to moneypit for loaning me the vacuum refill kit.

--Joe
Click to expand...


No problem, I was wonder status on the repair yesterday, I was swapping coolant in f150 I love simple systems fill radiator start truck wait 5 minutes refill and done
 
moneypit said:
No problem, I was wonder status on the repair yesterday, I was swapping coolant in f150 I love simple systems fill radiator start truck wait 5 minutes refill and done
Click to expand...

Can I drop off your tools tomorrow morning? If you aren't there I can leave them on your porch or something. Let me know.

--Joe
 
Axis said:
3100. Completely drained coolant & refilled with a vacuum kit today. I think I'm to the point I'll have to pull the new thermostat out and check it.
Click to expand...

if not lower intake gasket, it's a cracked head (rear) . Do a carbon test on the coolant.
 
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