Overheating and NEW thermostat not opening.

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One day my car decided to go all the way to the top of the temperature gauge. I'm still using the stock one and yes I know they suck but, it got to the L and the redline so I figured maybe my thermostat gave out. I replaced the thermostat and for one drive to the other side of town (few miles) everything was fine.

But, now within two miles of driving the temperature just keeps rising and rising. At first it goes to about the O normally then within 30 seconds it jumps to the L. So it looks like the thermostat isn't opening at all, but it's brand new and I'm positive it is in correctly (spring side in).

What could make a thermostat not open besides a bad stat?

Thanks.

 

[WHITE94COBRA]

Either a bad stat, or a poor job burping the system (no offense), burping our systems isnt that hard, but if done incorrectly or not at all will cause heating hazoc. I personally add coolant or water to my top hose before burping it, it is not nessesary to do this but It always makes it easier for me. There is a good write up on the site regarding how to burp the system.

 

[badstang123]

I would also guess that some air pockets in the system could be the problem.

When flushing out the cooling system. I always fill it up as much as I can and then start the vehicle (While cool) with the cap off and let it run until the thermostat opens. Then I let the vehicle run for another ten minutes or so to let coolant cycle through the entire system. I continue to top off the radiator until I'm sure the system is full. Then put the cap on and go test drive it. Check and top off overflow after.
- Justin

 

[HISSIN50]

You might be able to find some things to go over in the following tech note:

http://www.mustang-tech.org/wiki/94...cs#General_system_dynamics.3B_troubleshooting

Good luck.