Bad Thermostat???

[7upstang91]

I replaced the water pump and put in a thermostat(didn't know my stang didn't have one until I replaced it). After I did this I decided to run straight water for two days to make sure I had no leaks. I'm good on no leaks. BUT the car runs hot very hot. So i drained some water and put in Radiator cleaner. Now it runs hotter than before just under the red zone.

So is it possible the thermostat is not opening at all? Causing it to run hot?

When I come to a stop light it gets hot. Well normally once I take off the temp would drop back down. Now it doesn't at all.

Thank you!

 

[Mustang5L5]

Sounds like the car had a cooling issue and the previous owner tried to band-aid it by removing the theromostat.

More than likely your tstat is fine.

How's the condition of your radiator? Are you running the stock fan clutch setup? How's that? Are the fins cracked? DOes the clutch have resistance or does it freewheel if you spin it?

This on the supercharged car or the notch?

 

[7upstang91]

On the Notch. No cracks. Free spins. No the previous owner did not. I put on a Upper and Lower intake that was used, I didn't know that it didn't have thermostat in it. The radiator is fine. But it looks like this is a small leak coming from the t-stat housing(from the gasket) I just replaced that so I'm thinking it might be stuck close. I have heard of it happening so I'm going to try and test it.

 

[Mustang5L5]

Give it a shot, make sure it's installed the correct direction as well

 

[7upstang91]

Well right now since it is not working. I'm 99% sure I installed it the correct way. Maybe I didn't hopefully thats it. Thanks

 

[7upstang91]

Allright pulled it and tested it. Thermostat was bad. Replaced it and works great now.