Why is my 98 cavalier getting hot when it has a new water pump and thermastat plus, radiator has been cleaned?


Asked by mammajamma Jun 22, 2007 at 02:12 PM about the 1998 Chevrolet Cavalier

Question type: Maintenance & Repair

Why is my 98 Cavalier getting hot when a new water pump and thermastat have been replaced.  Also, the radiator has been cleaned.  When it is on the highway it does good, but when I get into town sitting at a light it gets hot.  The fans are working too.

13 Answers


Simple! Either your fan doesn't come on at set temperature i.e check the radiator thermostat, and fuue box; or you have coolant leakage. Check it. Other wise, you have a blown read gasket. In all cases, you'll experience coolant shortage. yeah!

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You think this is helpful.

How do you know if the water pump is working?

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Not Active

if you have replaced allthe parts,sounds like blown head gasket.

1 out of 1 people think this is helpful.

Sounds like you may have an air bubble in the system. Run the car and let it get warm and take the radiator off slowly. This will release any air in the system. Before starting the car again fill it up again.

3 out of 3 people think this is helpful.
Michael McGrail

Although this is a common shadetree mechanic trick, definitely not recommended. The release of cold air into the coolant chamber can cause it to crack! I would look whether the cooling fan is working, as this is probably and more commonly the problem. Also, change the radiator cap if you have not already, as its sole purpose is to provide a certain amount of pressure in the coolant system. If it is not providing the proper amount of pressure, it will cause the car to reach operating temperature prematurely and shortly thereafter overheat.

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Stuart House

I have a 97 Z24 with the 2.4 and it was getting hot, the the sensor for the cooling fan was corroded.

3 out of 3 people think this is helpful.
Kris Tyler

You might have an air bubble in the engine block. At road speeds, the temp will be fine, but at idle, the coolant doens't have enough pressure to get past the bubble, and folw stops, causing the overheat. One fix you can do is to find some long stretch of road where you can run at 55 mph for at least half an hour without stopping. The uninterrupted time at 2000 rpm should dislodge the bubble and sstop the overheating. If that doesn't work, a mechanic may need to pressurize the system to remove the bubble. A tiny leak can also cause this. When the engine is cold, the hole doesn't leak, but when it gets warm, it can actually let air into the coolant lines. It's very hard to find it.

1 out of 1 people think this is helpful.
Michael McGrail

A bad radiator cap or non-functioning cooling fan would produce the same symptoms.

3 out of 3 people think this is helpful.
Jonathan Page

Either your fan or a cracked gasket. Maybe even the block is cracked.

1 out of 1 people think this is helpful.
Adam Morgan

Cripes this is getting a bit long... Are you loosing fluid at all? If not you can pretty much rule out gaskets cracks ect... If you are, have the system pressure tested to find the leak and go from there... (I normally say to avoid shot gun fixing but I'd do the following since it's cheap) Air bubbles are a possibility, and sounds probable since you stated the fans are working, but the method for removing them isn't exactly accurate. You pull the car first and then let it idle to operating temperature. (If air is in the system you don't want it to heat up before pulling the cap (GAS EXPANDS MORE THAN LIQUID)... As the systems circulates the air will bubble up to the radiator cap (the high point). Top it off as it does this... Put a new cap on when you're done as radiator caps are cheap and there isn't a good reason not to. Do this and post back and let us know what happened...

1 out of 1 people think this is helpful.
David Bousfield

see if your relay to the thermostat is hook up corectly

3 out of 3 people think this is helpful.

bubbles should work themselves out,this sounds like head gasket,and you mentioned it did get hot,right?well how hot?let it warm up and before it gets at average range open cap and look for bubbles.this will show you if you have a head problem.and most of the time the water starts rto get nasty looking in fill tank.if you dont have fill tank,leave cap off just before average temp.but when taking it off use a big towel and eye protection,and do it slowly.then if water squirts fill it up and watch for bubbles or water blowing out the cap.if the thermostat is working it will circulate the water around,if the water isnt blowing up out of the tank or rad.it might be stopped up heater core,and that only wld. affect heater,but if t6he air blows water out it is a head gasket or hopefully not worse,cracked head.


First system has to hold pressure.....Next get a scanner check and check at what temp. do the fans turn on. Compare against laser thermometer to determine if the coolant sensor is accurately giving temp, corrosion on sensor can mask actual temps. My fan turns on late too.

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