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Old 04-22-2008, 03:02 AM   #1
DDRH
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98 cavalier overheating

I just bought a 98 cavalier and it started overheating. I realized there was fluid coming from the radiator so i had it and the thermostate replaced. It was fine for about 30 miles and then it stared overheating again. I popped the hood and there was fluid coming out of the reservoir. After i got back to the house i turned the car back on before it cooled off and the fan came on but only for a sec and then went off. I'm afraid if its not the fan or the water pump its the head gaskit but.. heres hoping. anyone have any ideas of how i could be sure of what it is.
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Old 04-22-2008, 03:56 AM   #2
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A common sign of a head gasket is water in the oil, which looks milky on the dip stick. If this is seen, it is likely the head gasket, however, this symptom may or may not be present. a pressure test can also work, but again, a negative result is inconclusive. A sure answer is to have a shop analyze the coolant for exhaust products, however you need a tail pipe sniffer to do this.
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Old 04-24-2008, 01:19 AM   #3
DDRH
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Lightbulb thanks

thanks for your reply. I took the car out yesterday and drove it about half the day and it never over heated and then i drove it to school today, just sat in the middle at about 195, it would get alittle higher but it would go down to alittle below it almost immeditatly after.. .. dang. hmm. Is it possible that there was to much water or the cap wasn't on tight enough or maybe air pockets, if that even happens, that was causing it to bubble out of the resivouir...
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Old 04-24-2008, 09:44 PM   #4
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First i would check the fluid level. Do this when the motor is cool. pop open the pressure cap and if you see coolant, its good. If not add more. Do you notice your fan turning on when the temp gets high? If not then sounds like you have a bad water temp sensor. 20 bucks at advance auto
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Old 04-24-2008, 10:01 PM   #5
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Quote:
Originally Posted by DDRH
thanks for your reply. I took the car out yesterday and drove it about half the day and it never over heated and then i drove it to school today, just sat in the middle at about 195, it would get alittle higher but it would go down to alittle below it almost immeditatly after.. .. dang. hmm. Is it possible that there was to much water or the cap wasn't on tight enough or maybe air pockets, if that even happens, that was causing it to bubble out of the resivouir...
If the cap wasn't tight, the system won't pressurize. A cooling system counts on pressure to be able to cool. If the system didn't seal, it would overflow, and it wouldn't cool as effectivly. however, if you replaced the radiator, (or that is what I understood), I would hope they put the cap on properly. It is not something that will magicly heal itself.
Do you know exactly where the coolant was comming from?
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Old 04-25-2008, 02:30 AM   #6
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hmm

Dang... worked fine yesterday all day, today drove it 15 miles and it got hot fast. The fluid was coming out of the reservoir. The day i bought the car I had the oil changed and the guy said that it wasn't the recommened cap that was on my reservoir, couldn't be that simple could it? I ran some radiator flush through it earlier and tommorrow i'm gonna run some stop leak i guess......
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Old 04-25-2008, 02:53 AM   #7
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If the fluid was coming out of the reservoir, you have a bigger problem than a little stop leak will fix. Instead of throwing random miracle fluids at it, find the source of the problem. I believe on your car the reservoir/expansion tank is pressurized. If this is the case, and you have the wrong cap, the tank will probably overflow. Here is a little cause and effect for you.
This is how it should work:
1. Engine generates heat, heating coolant.
2. coolant expands, building pressure
3. pressure prevents fluid from boiling
4. heated fluid flows through radiator and is cooled
5. cooled fluid returns to the engine and cools the engine

This is how it works when you have the wrong cap
1. Engine generates heat, heating coolant
2. coolant expands and fills/overflows reservoir
3. temperature continues to rise, coolant continues to expand
4. coolant begins to boil inside the engine
5. fluid boils over around misfitting cap
6. irreversible damage can occur to engine
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Old 04-28-2008, 03:03 AM   #8
cessnatech
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cessnatech

This sounds like the problem I had with my wife's 92 cavilier 4cyl eng. In our case it turned out to be the electric fan was shoot. If the car was moving it had air flow thru the radiator to keep the temp down. If you ran the eng with the car setting the fan would not come on and it would run hot. The fan should cycle on @ about 180 degrees and cut off @ about 200. A compression check would also give you a good indication of a blown head gasket. Good luck. (ps my wife's cav has 313k mi with no major eng work) you can't kill them. Cessnatech
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Old 04-29-2008, 02:00 AM   #9
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make sure the air is bled from the system...
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