Thermostat problem...

[PatrizioD]

So Im driving around tonight, and all of a sudden my temperature gauge goes from 3/8 to 7/8 in about 6 seconds. It then proceeded to drop down, and go back up really quickly...much faster than thermodynamic law would allow. So im thinking theres a screwed up sensor or something somewhere. Have any of you had this problem before? It happened while going about 35 mph in 4th, so I pulled over and shut her down. Te fans were going full bore, but I couldnt feel any excess heat off the engine, since it'd been running only about 20 minutes, and in 45 degree weather. It went away for the most part, but idling at a Burger King for 4 minutes made it run up again. When I pulled out, it went right back down to normal and stayed that way for the last 20 miles of my trip. Turned her off, fans went right off and Im confused as hell. Any help would kick ass, because Im stumped, and my wisdom teeth are starting to pound. This sucks ass...

[Z ROADSTER]

One of three possibilities . # 1 Blown headgasket . # 2 sticking thermostat . # 3 bad sensor & or connection .

[Sarge]

All original? Original DexCool? Pull the thermostat out completely....drive it for a few days with no thermostat at all and let me know.....

[PatrizioD]

Its all original, 19K on the engine. How do I go about pulling out the thermostat?

[LS2Tuner]

By removing the thermostat housing that the upper radiator hose attachés to. I think the two bolts are 10mm.

I would venture toward a bad sensor. You could stand under the hood with it running and shot the hose's and coolant with a temp. gun...............

[PatrizioD]

Ok so i just called up the dealer that I bought her from, and Im bringin her in on Monday. I got a warranty so i dont think its gonna cause problems in the wallet, but who knows. All I really want to know is if I can drive the car around without the engine either A) Exploding or B) Turning itself off at 80mph on the highway to protect itself. (Im into overclocking computers, and they turn themselves off when they get too hot, so it would only make sense to me that the ECU would have some similar function)

And I popped the hood and took a look at the radiator hose area and... :duh: I have no idea what the hell im doing under there. When I popped the yellow radiator overflow cap off, there was some brownish gunk in the top top holes, over the top arrow. THAT frightened me a little ::nightmares about castrol commercials dumpin sludge on my baby:: I cleaned it out and the coolant stick looks fine now... possibly a little low, but still covering the bottom hole.

[pocket rocket]

I just had twin turbos installed and my engine started overheating, so I disconnected the hose that goes to the head and filled. It still over heated so I did it again again again so after the 5th time it seemed to work good NO OVERHEATING. I guess it had an air pocket. Next DAY WELL now it doesn't seem to be over heating BUT the big BUT now the temperature gage reads COLD ALL THE TIME. so what gives HELP!!!!

[Sarge]

Did Nelson do the work? Jonathon probably screwed up the sensor

[rednari]

Assumming you have no mechanical failure, your problems are common on these cars, especially on the 04 models. It is a computer snafu that makes the gauges go crazy. Take it back to Pontiac. GM is aware of the problem and will cure it gratis.

If you changed over to mechanical gauges as I have, then you should follow the suggestions in the above postings. Never trust an electric gauge.

[PatrizioD]

rednari, what kind of mechanical failure are you talking about? My gauge went haywire, and the fan was going full speed. The coolant level was still at the cold fill point, and the reservior itself didnt even feel warm. This leads me to believe that something is sending a bad signal somewhere. Oh well, im bringing it to the dealership tomorrow morning. I just hope they dont expect me to leave it there overnight...

[pocket rocket]

You know I hate to take my car to the dealer, reason is I have a friend that left his car @ the dealer over the weekend for some paint issues and when he picked up his from for warrenty work and found it had an extra 200 miles on it. When he tols the manager about it they did nothing to the mechanic and to add insult to injury they didn't even fix the paint issues, in fact they added over spray all over the car. be afraid:

[Sarge]

You know I hate to take my car to the dealer, reason is I have a friend that left his car @ the dealer over the weekend for some paint issues and when he picked up his from for warrenty work and found it had an extra 200 miles on it. When he tols the manager about it they did nothing to the mechanic and to add insult to injury they didn't even fix the paint issues, in fact they added over spray all over the car. be afraid:

Bring it to Ancira in Boerne.....I know people

[pocket rocket]

So you have people,any name I can ask for/?/??//hummmm

[Z ROADSTER]

You know I hate to take my car to the dealer, reason is I have a friend that left his car @ the dealer over the weekend for some paint issues and when he picked up his from for warrenty work and found it had an extra 200 miles on it. When he tols the manager about it they did nothing to the mechanic and to add insult to injury they didn't even fix the paint issues, in fact they added over spray all over the car. be afraid:

Son-of-a bitch !!! That sounds like what I went through with my Vette & Camaro at different GM dealerships . And to make matters worse they busted the Vette's w/s then claimed it was like that when I brought it in for warranty work . Can you believe these fuckers . And GM wonders why people hate their stealerships .

[rednari]

Pat D, I mean that if you actually had a problem with the thermosat, like it being stuck open or closed, then of course recalibrating the computer by the dealer to correct the instrument cluster would not help your situation.

But try the dealer first because there is a GM bulletin regarding the issue, and especially since it sounds like the car is not really overheating.

[PatrizioD]

Well my baby is at the dealer now. They said it was a leaking water pump, which I guess makes sense. Im skeptical about going to dealers, and I think you guys all can figure out why based on your own posts. They had to ship in a water pump from somewhere else, so I might not get it back today.

On the way to the dealer, I noticed my Average MPG went down from 19.7 to 16.1...I havent reset that specific trip-o-meter (?) in a while, nor have I been punching the gas especially hard. Could the water pump problem be related to my decreased mileage? With gas as much as it is, I hope so...

And thanks a bunch for all the help guys

[LS2Tuner]

Yes, depending on the temp the ECU was seeing it can drastically effect mileage. Temp. sensors are only made to read liquid NOT steam. So yes when you have leaks it will read cold due to low fluid level. When the ECU thinks it is cold it runs it rich to warm it up like a choke on a carbed vehicle.

[Sarge]

So you have people,any name I can ask for/?/??//hummmm

Sean or Charlie...tell them Sarge sent you....

[pocket rocket]

hey thank you Sarge

[Sarge]

Let me know and I'll meet you up there....