Anybody ever have a stuck thermostat (closed)? - F-Body Road Racing and Autocross Forums

Any of you guys ever have a thermostat stuck closed? I swapped mine a few weeks ago for a Evans hi-flo, 160 stat and topped the fluid off. I then started it last night, and was trying to get the air out, but the temp on my aftermarket gauge climbs to 200-210 rather quickly (<5 minutes). Every time I let it sit and cool, it takes a little bit of coolant. (Checked it at 5:15 this morning, probably took another pint). It seems that there is an air pocket so big that the thermostat doesn't open up yet.

Few notes:

1. The aftermarket gauge sensor is on the passenger's side head.

2. Stock gauge is on the driver's side head. Stock gauge shows ~210....of course, that's what it always says from 160-225!

3. Is there air or vapor making the aftermarket gauge show ~210, while the stock one is upto ~190 according to the Mastertech scanner? If it was at 195, the fans would kick on (LS1Edit). I've yet to hear the fans kick on while attempting to get more fluid in.

4. I always shut the car off when the aftermarket gauge shows ~210 in fear of doing damage.

5. I've taken the hose off at the top of the driver's side head, and coolant flows right out, no bubbles.

I guess when I get home I'm going to try starting it up again and see if it will open again? I just don't know how long to wait before I fear the heads are getting too hot from no circulation and/or air pockets. If that doesn't work, I'm going yank the thermostat and see if it is defective.

It's weird, last time when I had the waterpump and t-stat out for my cam install (~15k miles ago), I had virtually no problems adding coolant and purging air without even messing with the little hose coming off the heads.---But, I did have the front of the car on ramps, elevating it about 10" higher.--Was that enough to make the radiator neck the high point of the system, thus allowing the air out quickly?

Just don't want to overheat my motor/heads!! (IMG:http://www.frrax.com/rrforum/style_emoticons/default/banghead.gif)

Teutonic Speedra... Teutonic Speedracer View Member Profile	Feb 4 2005, 06:07 PM Post #1
LS1 Inside! / Toolbox / Mechanical Engineer Group: Advanced Members Posts: 2,215 Joined: 5-February 04 From: NJ Member No.: 179	Any of you guys ever have a thermostat stuck closed? I swapped mine a few weeks ago for a Evans hi-flo, 160 stat and topped the fluid off. I then started it last night, and was trying to get the air out, but the temp on my aftermarket gauge climbs to 200-210 rather quickly (<5 minutes). Every time I let it sit and cool, it takes a little bit of coolant. (Checked it at 5:15 this morning, probably took another pint). It seems that there is an air pocket so big that the thermostat doesn't open up yet. Few notes: 1. The aftermarket gauge sensor is on the passenger's side head. 2. Stock gauge is on the driver's side head. Stock gauge shows ~210....of course, that's what it always says from 160-225! 3. Is there air or vapor making the aftermarket gauge show ~210, while the stock one is upto ~190 according to the Mastertech scanner? If it was at 195, the fans would kick on (LS1Edit). I've yet to hear the fans kick on while attempting to get more fluid in. 4. I always shut the car off when the aftermarket gauge shows ~210 in fear of doing damage. 5. I've taken the hose off at the top of the driver's side head, and coolant flows right out, no bubbles. I guess when I get home I'm going to try starting it up again and see if it will open again? I just don't know how long to wait before I fear the heads are getting too hot from no circulation and/or air pockets. If that doesn't work, I'm going yank the thermostat and see if it is defective. It's weird, last time when I had the waterpump and t-stat out for my cam install (~15k miles ago), I had virtually no problems adding coolant and purging air without even messing with the little hose coming off the heads.---But, I did have the front of the car on ramps, elevating it about 10" higher.--Was that enough to make the radiator neck the high point of the system, thus allowing the air out quickly? Just don't want to overheat my motor/heads!! (IMG:http://www.frrax.com/rrforum/style_emoticons/default/banghead.gif)

Teutonic Speedra... Teutonic Speedracer View Member Profile	Feb 18 2005, 04:05 PM Post #2
LS1 Inside! / Toolbox / Mechanical Engineer Group: Advanced Members Posts: 2,215 Joined: 5-February 04 From: NJ Member No.: 179	QUOTE (robz71lm7 @ Feb 18 2005, 10:16 AM) Just throw a stock one in and see what happens. Demand a replacement/refund from Evans if the stocker works fine. It seems you know how to bleed the LS1 colling system if it worked fine before. Yeah, I never had a cooling system problem or air, or anything until I did the swap, and I've flushed the system a few times before, and had the stock t-stat and water pump off for the cam install. I think I know what I'm doing. I'll be happy if the stock t-stat solves my problem. Then I can move on to bigger and better things.....like my Hawker and the lexan.