Is there a way to check for a stuck t'stat?

[GsxrMike]

My engine has never been hotter than 160* and almost never goes north of 130*. I have a 180* tstat and its new. Temp sender is working. I took several temp readings with a infared thermometer on the intake and radiator and hoses and they were all reading within +/- 5* of my guage. Is there anyway to see if the tstat is sticking open? It is new but has been installed about 6 times due to a leaky housing.

 

[Jason4x4]

pull it out, throw it in a pot of water on your stove with a thermometer, and see what temp it opens at.

 

[GsxrMike]

Anything else that would cause my situation? Motor runs good. The only time it hit 160* was when I couldn't get my 208 into 2wd after it popped out and I had to drive 2 miles home in 4lo and I was running like 4K the whole way. Timing and carb are good.

 

[Jason4x4]

Locked up Fan Clutch?

 

[GsxrMike]

NOPE...but now that I think of it I just changed my wires because my old ones were shot causing several cylinders to mis alot. I haven't driven it but once since then so maybe I will go for a spin tomorrow. Thanks!

 

[DEMON44]

My engine has never been hotter than 160* and almost never goes north of 130*. I have a 180* tstat and its new. Temp sender is working. I took several temp readings with a infared thermometer on the intake and radiator and hoses and they were all reading within +/- 5* of my guage. Is there anyway to see if the tstat is sticking open? It is new but has been installed about 6 times due to a leaky housing.

your upper rad hose should not get hot until the tstat opens.

 

[GsxrMike]

Guess its time for a new tstat because my upper hose warms with the engine.

What temp should I go with for the best performance? A little cooler is better isn't it? That is why I went with 180* before.

 

[tRustyK5]

192 is good. It'll run more efficiently at 192-200 than it will at 160-175.

Rene

 

[Chevy305]

Go with a BeCool 180* thermostat. Thats what I have and the engine never goes above 185*

 

[dyeager535]

Guess its time for a new tstat because my upper hose warms with the engine.

What temp should I go with for the best performance? A little cooler is better isn't it? That is why I went with 180* before.

Go with 195*. It's stock, and you make more power at hotter temps.

Thermostat is what controls engine temp if everything is working correctly. An engine can *only overheat* if the thermostat is working, never undercool.

 

[GsxrMike]

You don't make more power at hotter temps. The engine will run more efficiently at a higher temp but it will make a little more power at a cooler temp. I will just stick a 192* like Rene said and see what happens. Maybe I will go with synthetic oil too and see if I can get her to do a wheelie. LOL

 

[dyeager535]

More efficiently means more power.

It has been proven via dyno that the benefits of a colder 'stat barely exist, if at all. You cool the intake charge to make more power, however a cooler charge means fuel doesn't stay atomized as well, which hurts power. Colder intake walls ("wet" intake) will encourage fuel to condense on them. Not to mention thicker oil, different expansion rates of metal, and so on.

I think the takeway is that you need massive amounts of air, and a lot of velocity (IE, an engine being run hard and fast) to get the benefits of a colder 'stat.

 

[454k30]

The only time running a cooler t-stat is desired is for those with fuel injection. Keeping the engine cooler makes the computer keep the fuel/air mix richer and gives you a little more power.

 

[GsxrMike]

I read an article in a hot rod mag thats says otherwise but your opinion makes more sense to me. I stand corrected.

 

[dyeager535]

I wasn't able to find much online, I'll try hot rod directly in a minute.

http://www.streetrodderweb.com/tech/0706sr_cooling_guide/cool_guide.html Not a single manufacturer there recommends 160* from what I saw, one references factory.

Look at "Dan's Data" here:
http://www.timskelton.com/lightning/race_prep/powertrain/dyno_data.htm Note that even at 415HP, the cooler 'stat COST the engine 5HP. Could be something as simple as increased friction, or it could be more complex, like the ECM started retarding timing because it started to detonate. Dunno. That's only one test, granted.

Here they gained a whopping 2HP for swapping to a cooler thermostat, but that was indeed due to the computer retarding timing at the hotter temps...when moving this would be a non-issue, since the engine would run at thermostat temp, which is under the problem area. Even then, 2HP? Give me a break, that's margin of error territory.
http://www.highperformancepontiac.com/tech/hppp_0601_2003_pontiac_grand_prix/ignition.html

 

[GsxrMike]

I would think running a little warmer engine would make it last longer as well so I will go with 192* and see what happens. Thanks!

 

[Russell]

I have a similar problem with the 4.3L V6 in my 96 DD. Goofy thing won't warm up beyond 170F, even though I have a 200F stat in it.

Winters get cold up here, and I want that engine putting out as much heat as it can to keep my sorry backside warm! Engine also takes forever to heat up as far as it does. Once it does warm up, the temperature swings wildly instead of being regulated at the proper temperature. Changes as much as 20 degrees in either direction. I've put 3 or 4 t-stats in it now, all of which I tested in the pot of water and confirmed that they work, gauge is accurate too, infared thermometer around the base of the t-stat housing.

I'm planning on taking my fan off for the next week, its going to be around -15F for a while, and see if it warms up then.

 

[dyeager535]

I noticed on mine that when it gets cold out, it does seem to "overcool" a tiny bit. If it's -15*, I might see cooling being so effective that even with a shut thermostat, the coolant may drain off engine heat.

A smaller radiator would be interesting to try, but that's a fair bit of work for seasonal stuff, IF one is even available.

Wild swings would seem to indicate the t-stat isn't working right, but you did test them. If the coolant in the radiator is cooling off very quickly, then being dumped into the engine, if the thermostat wasn't operating smoothly I'd expect to see swings in temp.