Thermostat in am '03 Grand Prix 3.8L

[mr.elmwood]

I now know I need to change the thermostat. Upper hose is hard and hot. Now, I have not had thermostat issues in decades, so, what I am seeing, confuses me.

I have a temp gauge. Around Bugtussle, car does not warm up because I do not go far enough. This last few days I was out on the highway, car warms up to the normal spot. Get to the city and the gauge moves from normal up to the 100°C, starts slowly creeping higher. It has never done this before. I turn off the AC, turn on the heat, bring the temp down. Drive on the highway, temp stays normal, maybe a half notch higher. Slow down in bugtussle and the gauge starts creeping up again. 

Just now, four blocks to the liquor store, 4 back, it starts showing hotter than ever for that distance. Fans are coming on. Upper hose hard and hot.

Yeah, but, if the thermostat is not opening, why am I not over heating all the time? Is there enough airflow on the highway to keep it cool enough?

I will go over to Ad-Vic Bearing Auto Parts and buy a thermostat from the guy that owned the car before me. This is a small town.

[legitimate_bidder]

Mr. Elmwoodrow, I assume that you've checked to make sure the 'lectric fan is coming on, and that the radiator fins/AC condenser fins are not clogged-up, thus preventing sufficient air from circumsizing through where it has to go to do it's job? And that the radd-E-ator is not clogged internally?

When ever there is a weird cooling (read: "overheating") problem with one'a these injuns, I always fear the dreaded head gasket or intake many-fold gasket is in at least a partial stage of failure.... 😞

[mr.elmwood]

LBJ, everything is working. Refer to my hot and hard remark.

Fans are working, nothing clogged, have not looked in rad yet, will tomorrow. I am due for a coolant change as per the manual.

[mr.elmwood]

Remind me. Check the level in the coolant tank. I forgot to do that.

[legitimate_bidder]

> "Refer to my hot and hard remark." <

Uhh, nooooo.....I'd rather not.

The more I think about it (especially the aforementioned remarks) the more I think your rad. is internally clogged.- Hence the "hard" part. I'd try running some water through it with the drain **bleep** open (do they still have those?) and see how it flows. Just let the coolant flow out into the street. Extra points if you do it in front of a leftist's/Greenie's house. (Just make sure it doesn't puddle, so no bow-wows or meows end up drinking it)

[ripsmc]

If you're still using Dex-Cool antifreeze you might check for a clogged radiator. This is a common problem with the use of D-C.

It usually shows up in the top of radiator, overflow bottle, and so on pretty easily.

[atikovi]

Are you perhaps confusing normal behavior for an imagined problem? I have a red Sunfire convertible for sale (hint) and it too would show the gauge rising in stop and go traffic but never actually overheating. I replaced the radiator, cooling fan, thermostat, coolant, etc. with no significant change. Turns out that many GM cars of that era are programmed to run hot for emissions reduction. Unless the gauge gets close to the yellow band, like within 1/8th inch, I wouldn't worry about it.

[marinermikes]

On short runs your gauge will fluctuate. Most of the guages on my gauged vehicles on warm up will go past the normal run temp before the thermostat opens. You can actually watch it come down when it opens. Or,  It may be that the sensor that turns the fan on is defective and not coming on soon enough.  Or a plugged rad.  A new thermostat is always a good idea. 

[sockmonkeydave]

@mr.elmwood

Sounds like the thermostat to me, just a few bucks to change.

The other option is clogged radiator, or motor cooling ports, inside the engine.

Check the hoses when hot, an old hose will pinch off,

and seconds after you shut the car off, will go back to normal.

But yes, at speed the air will cool the engine.

ie... VW... and aircraft engines... all air cooled.

[legitimate_bidder]

C'mon, guys..... Mr. Elmwinkle is noticing something out of the norm here- if what were happening were just typical behavior, I'm sure he wouldn't have just started noticing it now.  In his original post, he explains why it's NOT the thermostat.

Sounds like the radiator needs a boiling out, and/or the system needs a good flushing. Time for him to go see @tony1963, as I hear that he's an expert at flushing.....

[atikovi]

Brand new radiator is like $40 shipped to your door.

[legitimate_bidder]

DAAAAAAARN! Radiators for anything i dirve are always at least $300. For my little tractor, they wanted $500! (Thank goodness there are still old-fashioned radiator shops around here...got it boiled and soldered for $60)

[mr.elmwood]

Not having done trouble shooting in a long time, I started at the thermostat end. It worked, better. Put old thermostat suspened in a pot of water, bring to a gentle boil. It seemed to open.

Wait for the car to cool down, remove rad cap, coolant looks like runny chili. 

Regardless of what the gauge may or not say, it ain't gonne be anywhere near right when the coolant has the colour, consistency, and taste of diarrhea. I ain't doing this. They guy I bought the car from, I will pay him. His kid needs tuiton for the fall semester anyway.

[legitimate_bidder]

Oooooo.....that's not good on SO many levels!

First, that's the way he maintains a car, and you're gonna let him fix it? He's the one who "broke" it!

Second: This portends bad things for not only the condition of the cooling system, but how the car was[n't] maintained overall.

And tird (and i do mean tird...minding the auto-censor of course...) even Wrecks-cool....I mean Dex-cool isn't likely to get THAT funky. Sounds like someone may've been dumping massive amounts of some sort of mechanic-in-a-bottle in there to "fix", as I said, with these injuns.....head gaskets and intake manifold gaskets.

Hopefully though, ya get that thang dewshed out with some industrial strength flush and LOTS of water, and she'll be O-K ......

[atikovi]

From Crapolier to Grand Pris, Elmwood is movin on up.