Unexplained overheating

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  #1  
Old 07-07-06, 04:06 PM
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Question Unexplained overheating

My wife has a 1999 Chevy Cavalier with a 2.2 liter engine. I started smelling coolant inside the vehicle. I accessed the heater core and found that it did not appear to be leaking. The car sat in garage for a few days and then after I put everything back together, it started running hot. It would be in the red before I drove 1/8 mile. I changed the thermostat. Pulled and checked the waterpump. I flushed the radiator and replaced a the upper hose. Nothing has helped. The coolant smell is apparently coming from overflow from the reservoir. But I can't for the life of me figure out why this car runs hot. It started running cool for a while and I drove it about 70-80 miles. Then it started running hot again. Not in the red but close. Can anyone please help?
 
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  #2  
Old 07-07-06, 04:16 PM
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suggest you have the cooling system checked out at a shop were they can test it for exhuast gases getting in the cooling system wich would be a sign of a head gasket or head problem unfortuanatly head gaskets are quite common on the 2.2 liter engine.
they will aslo be able to leak test the system and check to see what temnperature it is actually running at and confirm the cooling fan is working.
 
  #3  
Old 07-07-06, 05:03 PM
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Did you remove the heater core? If so then this is likely where your overheating problems began. Since you didnt tell us that you are noticing puddles of coolant im going to assume you dont actually have a leak. It sounds like you have air in the system. This car has a very specific bleed procedure for the coolant system. As bejay mentioned it is always possible you have head and or gasket failure. But lets hope not. Thank your lucky stars if not.
Start by finding the bleed screws. There may be one, but there may also be two. Look in the coolant pipe that runs along the front of the engine between the radiator and the engine. Its about a 5/8 pipe. This pipe runs around the end of the engine where the transmission is and goes into the thermostat housing, if memory serves me. There may be a bleed screw at the thermostat housing, but there is definately one closer to the water pump. Start the car and open the bleed screw at the thermostat housing. Let it run coolant out for a few minutes until you see NO air. Close this one. Open the bleed screw at closer to the water pump and do the same. Now, remove the 1 or 2 rubber lines that go into the top of the reservoir. Let them sit there so that you can observe them. While the engine is still running, every 10 minutes or so open the bleed screw (the one on the water pump end of the engine) Let it spit until you dont see anymore air. Eventually you will see coolant start to bubble out of one of the lines that you removed from the reservoir. When you do replace these lines and fill the reservoir. This should take care of your overheating condition as long as you dont have any leaks. Be sure to have the cap on the reservoir during this procedure.
Hope this is helpful to ya,
Billy
 
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Old 07-07-06, 05:09 PM
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So Billy,

What about that theory of just taking the vehicle and finding a steep hill and then opening up the radiator cap to burp the car, as you so often hear? Is this easy cure-all too good to be true?
 
  #5  
Old 07-08-06, 05:41 AM
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Originally Posted by DaVeBoy
So Billy,

What about that theory of just taking the vehicle and finding a steep hill and then opening up the radiator cap to burp the car, as you so often hear? Is this easy cure-all too good to be true?
Didn't seem to work on my '99 Blazer 4.3, but then again that one had so much Dexa-Goop (tm) in the heater core that I had to have a friend back-flush the heater core at his garage. I don't burp cars, generally I fill everything up to capacity and let them idle for as long as it takes, adding coolant as needed. As the thermostat opens there's usually some activity at the radiator neck then the coolant drops for the last time.

Christopher
 
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Old 07-08-06, 04:10 PM
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Years ago, I can't remember hearing about all this burping business. Then again I was younger and maybe missed out on this detail simply because MY vehicles never had any trapped air problems that I can recall. But, my Dodge vehicles I have, have these plugs in them at where the thermostat is and I have the understanding that this is where you let the air out.

Years ago, I was always under the assumption that when you had the radiator cap off and the coolant was circulating when hot, that any air would be expelled at the open radiator cap. But there must be vehicles out there, by design, that this must not be good enough.
 
  #7  
Old 07-08-06, 06:00 PM
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Originally Posted by DaVeBoy
Years ago, I was always under the assumption that when you had the radiator cap off and the coolant was circulating when hot, that any air would be expelled at the open radiator cap. But there must be vehicles out there, by design, that this must not be good enough.
On the Blazer the heater core was slightly above the engine, I remember when we had stable engine coolants that you mixed 50/50 with water and knew what to expect. Dexacool is a really good coolant for extended use, mine has been in the Regal since the car was new and it's just turning 96,000 miles. Never runs hot even during the summer. Dexacool does have a problem in which it tends to thicken with exposure to air. The Blazer had a seepy heater core which allowed air into the system and it got thick enough to block the heater core when I had to take the coolant out to replace a bad water pump. Flushing the system gets rid of the goop, but you have to make sure the system is airtight as well as watertight.

Christopher
 
  #8  
Old 07-08-06, 08:50 PM
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Did you do like bejay asked & made sure the cooling fan was running
 
  #9  
Old 07-09-06, 09:58 AM
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Yes gentlemen, long gone is the day of just letting it run till the air bleeds off on its own. I use a tool called an air lift almost daily. I work on Dodge cars and vans every day as well as some other makes and models. Any time I do anything that involves opening the coolant system i use my air lift to expel any air. This is also an awesome diagnostic tool as it will let you know if you have any leaks instantly. As soon as you cut off the air supply the needle on the gage will start to fall back to zero if you have a leak. The way the manufacturers are making cars today they unfortunately arent always keeping the logical position of things at the forefront. They pretty much just cram things in where they can find an inch of space. Then you have vehicles like minivans that have rear heat and A/C systems. There is no easy way to bleed these as the flow of the plumbing allows for plenty of potential positions for air pockets (say that 5 times fast.... LOL)
Good Luck with your car Okie and let us know if there is anything else we can help you with.
Billy
 
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