Engine runs cold?

**klaussk** · 02-11-2014

Hey guys and gals! I'm new to this site and I have a 2005 grand prix base model with the 3.8l. I'm pretty new to these motors but not new to GM. Well to the point. Unless I'm at idle for a long time with the heat off the car never heats up past a quarter of the way up the temp gauge. I already put in a new thermostat and purged the system and it still does this.I bought the stores "best" but is it still possible that it's a defect one. I should have tested it first. Apparently these new thermostats have a fail safe that leave them open when they go bad (makes sense). But When you first start the car I can't feel fluid going through the top radiator hose. Any ideas ?

**Scottydoggs** · 02-11-2014

if its failed it will be stuck open when you take it out. so id check it. parts do come defective from time to time.

if you want to test it. all you have to do is put it in a pot of water on the stove top and then wait for it to open as the water gets hot. if you have a thermometer you can tell how hot the water is when it opens. should pop open at 195.

**loopy smurf** · 02-11-2014

The other thing is, it's exceedingly cold out right now. During the winter, my car never gets above that first line on the temp gauge, but my heat is hot, and I get no check engine lights. When my thermostat was bad, the car never really got into the reading area of the gauge, and my check engine light would come on because the car never got into operating temp. If your heat is hot, and you have no check engine lights, I'd just leave it be, and see what happens in teh warmer months.

**02NavyBlue** · 02-11-2014

You shouldn't feel anything going through the upper hose until it gets to 195°, so that's normal. Once you do you should have hot heat, and the temp gauge should be reading in the 195°-200° area. If no heat then feel the heater hoses, both should be hot if the blower motor is off, turn it on and the return hose would be a little cooler than the supply.

Also on temp gauges, they're not accurate all the time on cars. Mine is accurate to about the exact degree, but some aren't. If the upper hose stays cold until it's been running for about 10 minutes from a cold start then it's operating as it should.

**spazzz** · 02-11-2014

You didn't buy one of those Motorad thermostats did you?
Big time fail, if you did.

**02NavyBlue** · 02-11-2014

It probably is since they're the only name brand that makes a fail-safe I believe. I'm not too happy with their thermostats.

**klaussk** · 02-11-2014

My heat is hot but nothing like my silverado. I think I'm going to change the cabin filter and see if that helps. It was a Virginia beach car so I'm sure its full of sand. It did give me a thermostat code with the reader along with a bunch of other codes. The car had a little "episode" about a week ago. It had been sitting for about 4 days and everyday was well below 0 degrees. I tried to start it at like 7 in the morning when it was -10. It started and was going crazy. It would randomly rev up to like 4 grand and back to idle. I shut it off and restarted it and it did the same thing. So I took the truck to school and called my wife to tell her to try to start it later that day when it was like 20 degrees outside and it started just fine and had no operating issues. It gave me like 6 codes at the auto store. The thermostat (which I believed because the engine was running cold) a fuel pump fault, clogged catalytic converter , hard shift, and 2 others I cant remember. Going to take it back this weekend to see what codes come up after I unplug the battery for a little bit. I'm not sure if all that stuff is really wrong or if those are from the cars little freakout.

**sseilmnop** · 02-11-2014

Make sure that you are giving a 195 thermostat. I believe they list a 180 as an option. I run 195 in the winter.

**Travisgt2** · 02-12-2014

i run a 180 year round my car never gets fully up to temp putting around town blows hot heat though and it has to sit for at least 20 min before it gets warm so the cold thing it will happen btw i have a durelast thermostat

**sseilmnop** · 02-12-2014

When it's below zero you can feel the 15* difference. I no now someone is going say 180 isn't that bad.

It is 15* less than 195. If the girls are cold they will sit in my car not yours.

**klaussk** · 02-12-2014

Man I really don't want to swap thermostats every season. would it hurt to run a 195 all year

**sseilmnop** · 02-12-2014

Run 195 all year long. Next rime I'm at the turner in getting it fans set back for 195.

**Scottydoggs** · 02-12-2014

Originally Posted by klaussk

Man I really don't want to swap thermostats every season. would it hurt to run a 195 all year

you in no way need a 180 t stat. its doing 100% nothing good for you. put the 195 back and your car will love you for it.

**klaussk** · 02-12-2014

I think it had a 180 in it and thats what the auto store computer said. Anyone know the part # for the 195 so I get the right one

**Scottydoggs** · 02-12-2014

the box will say what it is. also should be stamped on the t stat its self.

and how did a scan tell you what t stat's in there? thats not possible.

**02NavyBlue** · 02-12-2014

The car should have come with a 195, it's designed to work at that operating temp. Although there's no need for a 180, it will run just fine with a properly operating 180. I swap mine out for a 195 for the winter because I'm a heat freak so I need all I can get, and run a 180 in the summer just because I want to. Just a preference, if it can run normally at a cooler temp than why go higher, that's my thought behind it even though there won't likely be any positive effect from it.