Sticking thermostat=overflowing coolant?
 

I'm still trying to sort out my overheating problems. The symptoms are pretty simple..........When the engine is pretty well heat soaked, like say after driving it for 15 minutes or so...........I can sit and idle it for awhile.........with lights on it stays 170-190 with the fan coming on and off.............with lights off it fluctuates 195 to 210, once again fan on and off..............

If I then stop the car, with hood down, I will hear gurgling as air seems to be heading to the overflow tank..........but after about 5-10 minutes it will completely overflow and spew out about 1/2 a gallon of coolant on the driveway.................

So far I've replaced both caps to the filler neck (Mazda original equipment) and the AST (even increased that one to 16lbs), and I've also purchased the $50 kit from NAPA that determines if you have exhaust gas in your coolant.............that gave me a negative result...........

The only thing I can figure out would be:

1. The thermostat is sticking (I'm only throwing that in because others have suggested it, but I'm not sure why that would cause my symptoms after the cars at rest)........

2. I DO have a bad seal, but it's only leaking the exhaust gas into the coolant AFTER it's heat soaked and THAT's when it's letting the exhaust gas in............the problem is that the kit for testing it is sort of impossible to use after you've got the car heat soaked because then your cooling system is under pressure, and to use it you have the filler neck cap off.................

HELPPPPPPPPPPPPPPPPPPPPPP!!!! and thanks.

David

Any aftermarket cooling parts? If someone put the wrong coolant in, freaky things could happen.

MrZ,

The coolant is experiencing localized boiling around the turbo exhaust manifold after you shut the car down which is increasing the pressure of the system and allowing coolant to bypass into the overflow tank.

There's really not much you can do about it short of an electric water pump or going to a different turbo setup.

The fan mod helps, but it will always be there, as coolant flow is stagnant when the engine is off.

I guess my only question is.....................why is this happening now................I've had this car two years (it's at 75K now, original motor)..........and I also have had it at the track several times and ran the piss out of it..............much harder than a little 15 minute drive................and I never had this happen before....................now it's kind of a constant thing...................

???????????????

TIA

David

Try changing the thermostat. It's cheap enough. :)
LOL. Ever since I changed mine... it takes 15-20 minutes to get my FD up to operating temp. (180F)