Changed rad, TStat and cap in early summer and all has been well until now, including running in heavy stop/go traffic in southern summer with AC on. Driving to church this am, turned on heater for first time since TStat change and car overheated. Felt upper hose and very hot, rad very hot, Cap strained from pressure and bottom hose somewhat cool. Seems a failed TStat, no? Also, NO heat inside car. After relieving cap pressure after mass, drove home, all well tempwise until turned on heater - no heat again and temp spiked quickly. Tried A/C and it blows ice cubes with no temp issues. Finally hoped to unstick TStat by running high rpm for awile to no avail. Suggestions? Is this a mechanical or bleed issue? Would think that running heater would alleviate hot coolant issue not aggravate it - in race classes where it is required to keep heaters, one turns on heater full blast to help with overheating so somewhat confused. Obviously I am not accustomed to working HVAC issues.... Thanks for any help.

 

I think you have an airbubble in your system from when you changed the thermostat. Bleed the air.

 

 

I had an issue like this but i had the aem hooked up on the laptop to actually see numbers...

I the same issue.. no heat... and kept wanting overheat... i ended up changing the thermostat and bled the hell outta the coolant... problem solved.

 

Also make sure to turn on the heat to max while bleeding. This will prevent trapping of air in your heating circuit.

 

so bubble can can block heater and keep coolant from flowing to out lower hose?? Any sure fire tips to bleed it? Tried the jacking up the rear and worked ofr AC but eventually failed heater test. Definitely a bitch to bleed this thing, no? Any way to check TStat except remove and use temp prbe in water bucket or you'll pretty damn sure its a bubble. Have a friend with street shop that has cooler exchange machine - would this be sure fire?

Thanks

 

If consensus is the bleeding procedure - is there an expert in Atlanta where I can take it? Tried the lifting of the rear - even lifted the front all to no success.

Thanks

D

 

You don't want to jack up the rear. Jack up the front. Make the bleed valves or radiator the highest point in the cooling system. All 3 times I have (re)installed radiators, I had to bleed the system 4-5 times with the front raised before things finally settled down to normal. Luckilly, my driveway has a dip in it that I can use to get the front of the car 4-5 inches higher than the rear.

 

hmm, when i bled my system, i just filled overflow to max, turned on heater full blast and let car idle. it sucked up all the overflow, then filled the overflow back to normal. idled some more. basically it bled itself.

your mistake was not running heater right after install. when you turned on the heater, that part of the system had air in it and powned you.

 

When I changed my rad fluid, I had to open the bleed valve. No problems.