I think my thermostat is messed up

syphon

Registered User
So I suspect that my thermostat is stuck open, but I want to run by the symptoms with you guys to see if I'm right.

1. The car stays cold a long time. My car knocks when cold, and it stays cold for about 15-20 minutes after starting it. I can warm the car in my driveway for 15 minutes and it'll still knock until I've driven the car a little bit.

2. Heater isn't completely hot. I recently took a small road trip (about 60-70 minutes on the freeway) and even after it running for over an hour, the heater is blowing warm air at best. I thought the heater core might be clogged up, but in junction with the other problems, I think the thermostat might be stuck open.

3. When I first got the car in the summer, it would warm up so the gauge was sticking straight up (between the R and M of norm) but now the hottest it EVER gets is just barely above the blue area in C. At first I attributed this to the fact that during the summer, my heater was always off. But now that it's winter, my defroster is always on.

If you guys agree that the thermostat is to blame, can you give me some tips on replacing it? I've seen thermostats replaced before, but I dont even know where it is on my car, or how to replace it.

Thanks guys.
 
Last edited:
Your thermostat is inside the gooseneck assembly that your upper radiator attaches to. It is held in place with two bolts (10mm head)and is a relatively easy swap. I would look at that as the first step. You might also want to flush out your heater core, just unhook both hoses and run water through from both directions. Hope this helps.
 
therm

man replace that therm. mine did the same thing.but mine kept the water from the engine. guess what happened!!you guessed it the head gaskets! make sure completely flush that cooling system too. All of the 3.8's have problems with the cooling system.I should know, this is the 3rd 3.8 car I've had that has blown the head gasket because of problems like these!!
 
Exact same problem here, and does your...

I recently changed out the heater core in my 89sc and noticed that after installation, the air from the vents was only warm at best, even if I let it idle for awhile. However, if I put my AC button to "Max AC", it heats up ten fold. I think this is because the air gets recirculated in the car. Does yours do this as well?

Mine runs very rich, and I have checked all codes. The engine runs good, but lack power big time, as my temp gauge never moves past the first notch on the low end of the scale, unless I am in 100 degree temps and stuck in traffic.

Thanks

Phil Stocker
 
Thermostat Change
by: Scott Long

1. Remove upper radiator hose
2. Remove serpentine belt (18mm bolt on the tensioner)
3. Remove tensioner (18mm bolt)
4. Disconnect the temp switch (slide the connector up and off)
5. Remove bypass hose going to water pump from housing
6. Remove two bolts (13mm and 10mm if I recall)
7. Remove housing pull old t-stat out
8. Scrape gasket off housing and intake manifold
9. Put new t-stat in housing
10. Put new gasket on (or make one from gaket material)
11. Take the two mounting bolts and stick them through the
holes of the gasket
12. Start threading the bolts back in, then line up the gasket
perfect and tighten the bolts down.
13. Replace bypass hose
14. Reconnect temp switch
15. Replace upper radiator hose
16. Loosen bleeder screw on housing (13mm)
17. Fill radiator with coolant, when it starts bubbling from the
bleeder screw, tighten the screw up.
18. Replace tensioner.
19. Replace serpentine belt.
20. Loosen bleeder screw again, start engine, when coolant
over flows, tighten bleeder again. That way all air is out of
your cooling system.
 
don't tighten the housing bolts to tight because it will bend it and won't seal right. then you will have a leak and you'll have to use alot of sillicone to get it to seal right. ford want's $176.00 for a new t-stat housing. you should consider a robert shaw t-stat while your at it, it worked great for me as i had high heat problems, very high heat. burned up three engines that ford put in, and they said it's normal temp should be around the r and m.it never ran that hot before they put the new engine, water pump and radiator in it. i put a robert shaw 180 in and it now runs on the n at idle with no fan.
goodluck
joe
 
Back
Top