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erratic temperature readings

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Old 07-08-2006, 09:55 AM
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Default erratic temperature readings

Driving around today, I noticed that my fans were still running, even after I turned the car off. After that, I started paying attention to the temperature gauge and noticed something peculiar. First, at stops or slowing down, the temp gauge will spike into the red in less than a second. Also, once at 45-50 mph, the gauge will instantly drop back to the 210 mark, then slowly work itself back into the red. I pulled over and checked the engine coolant, and it was at the "hot" level, so I just did my best to limp home..set off the "check gages" light several times in the process. Once home, I checked the engine coolant again and it still was at the right level. I added some more coolant and now it's sitting in my driveway w/ the hood up. It's been high 70s with very low humidity lately, but the car has never done anything like this...even in the high temp/high humidity wave that just swept thru VA

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Old 07-08-2006, 02:27 PM
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Don't know, but I'd look around and make sure the ECT sensor/wiring/connector looks good first.
Old 07-08-2006, 03:11 PM
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Check to make sure you aren't low on coolant.
Old 07-08-2006, 05:37 PM
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Coolant level is fine, and checked all the connections. so i decided to clean the K&N while i let the car cool down a bit. Well, finally got finished cleaning the air filter, so i popped it back in. I take advice from another forum and let the car get up to normal operating temperatures, and then try the bleeder screw. Well, when I open it, coolant immediately begins to pour out. I decide to drive it around, close to my neighborhood, to see if the temperature will work itself up. Cruising at about 50 mph, sure enough, the temp. gauge begins to rise. I pull over and open up the bleeder valve, and this time steam comes out. Alot of it. I leave it open for a few minutes, checking the gauge every once in a while...to my dismay, the temp gauge not only continues to rise, but goes off the scale. My engine starts to stutter, so i shut it off and notice coolant pouring from the reservoir and coming out of near where the trap door for the foglights are. I let the car sit for a bit, then start it up again....I get maybe about half a mile towards my house and the temp gauge has gone off the scale again, and the engine starts stuttering again. I pull off into a neighborhood and try the bleeder again...more steam comes out with a few spurts of water. I limp the rest of the way home and pull into the driveway just as the temp needle goes off the scale again.


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Old 07-08-2006, 10:33 PM
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I'd start by pulling and checking the easier things - radiator cap, thermostat, hoses. Oh, where is the bleeder screw on the LS1? I always used kept the radiator cap off to 'burp' any air when flushing the coolant. I do remember reading that the car goes into limp mode when overheating to try and prevent damage - I wouldn't totally rely on it however.
Old 07-09-2006, 12:46 AM
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Jack the front of the car up about a foot, open the rad up * car cold * start car.

Let car warm up, keep adding coolent to the rad untill you can't, then let it warm up, you should be able to see the coolant rise, as soone as its near the top of the rad tube, about to go into the over flow if the cap was on, blirp the throttle, its gonna throw fluid a bit, but not bad. Cap it and let it warm up the rest of the way, see if that works ( removes air from the system )

If it doesnt. check your stat
Old 07-09-2006, 02:15 AM
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clogged thermo was the culprit




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