Overheating upon driving after 5-15 minute shutdown, need expert advise.
 

I have a strange problem; my car will overheat if after driving for awhile (not overheated-running cool ~170°) I shut the car off and then start again after leaving it sit for about 5-15 minutes. I have changed the radiator, cap, t-stat, flushed the heater core, bled the system and tried water wetter. The car never overheats as long as it runs continuously, even racing or at a stop in 100° weather with the AC on or off, it normally runs below the 1st mark on the gauge (160° stat). It behaves as though the heads are heat soaked and are boiling the water when it isn't running which then pushes a bunch out to the expansion tank and then I've got an air pocket when I start again which causes me to overheat the next time I start the car. Anyone else experience this, I know this isn't normal, is there something that could be plugged that can cause this? It didn't use to do this even with all of the old stock stuff.

Shoebox, Injuneer or anyone, any ideas

Re: Overheating after 5-15 minute shutdown, need expert advise.
 

Did you replace your rad cap?

Yes I replaced the radiator cap, and the overflow line is on the correct fitting. It didn't use to do this until the seals started going bad on the radiator end tanks, I overheated a couple of times because the radiator would hold presure to push coolant out to the overflow but would not suck it all back & things would continue that way till I either blew it back in or the car overheated. I replace the t-stat & cap & checked all of the hoses before I found it was the gaskets in the radiator end tanks but even with all of the new stuff it still does this wierd overheating "sometimes" if I drive my car again after it has been sitting for a SHORT time. The strangest thing is that it is running cool & fine before I shut it down but overheats after I start back up (only if I wait 5+ minutes)
By the way, no water in the oil, no oil in the water, no water (or white smoke) in exhaust & the engine compresion check is good. I have a new 160° stat, a PCM4Less chip & my fans work perfectly. If it wasn't for this one wierd issue I'd be thrilled with my car, it runs perfect in every other way.

My car seems to do something similar. I have a 160' stat and fan switch, and it rarely goes over 190' when running. After shutting down for 10 mins and starting back up, the temp will be up to 230' or so. I haven't worried too much about it though.

My car also used to make that gurgling/bubbling sound after shutting down like you described. I fixed that issue by replacing the overflow coolant line .... it had a very small leak underneath the battery.

Thomas.

When I first start up it's fine but it quickly overheats to the point of boilover and "check engine" lights and I have to shut down, let it blow off and refill & blead it. Then I'm back on the road with no problems until next time (might be days later)

If you are having to rebleed just about everytime, I would say you have a leak somewhere which is allowing air into your system. Go to your local parts store and borrow a pressure tester and put that on, it should help you to find your leak.

Could be a bad thermostat I guess. Maybe it just works sometimes, I had a similar problem and thats what it turned out to be.

umm that sounds normal.. when you shut off teh car the WP stops spinning, so the water sitting in the motor will get really hot..

I don't have a problem with it heating up from sitting, I have a problem with it going from normal to puking its guts up within 5 minutes after the restart, it didn't use to do that and I'm at a loss for why it's doing it now.
I regularly travel between different altitudes and depending upon where I am (high or low) I can remove the radiator cap (when cool) and I will either find the system under presure or under vacume, so I know I don't have any leaks.
Maybe there is some intermittent thing that I'm not finding, it doesn't do the puke thing all the time.