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Over Heating Problem

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Old Dec 3, 2010 | 12:49 PM
  #21  
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Originally Posted by 8VETTE7
What does an electric fan have to do with the shaft of the water pump being metal? dgrant3830's post doesn't imply any mechanical fan. READ IT CAREFULLY. The shaft has a pulley on one end and the impeller (blades as he called them) of the waterpump on the other (inside) end. I would agree that the shaft is highly unlikely to fail.
Yea, I agree. I understood exactly what dgrant3830 posted and was thinking the same thing. Mechanical water pumps are pretty simple. The only one I've seen fail was a lockup due to a frozen bearing and the thing was howling like a banshee till we shut it down. It was Olds 455 from a different era.

If the OP has access to a pressure tester it should take all of 10 minutes to see if the system is holding pressure. Short of that, replacing the cap is cheap and may do the trick but I personally hate wallet diagnostics.

Last edited by Cratecruncher; Dec 3, 2010 at 12:52 PM.
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Old Dec 3, 2010 | 02:22 PM
  #22  
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Sounds like the same issue I was having. Mine was bouncy on temp for months. But it would only bounce 20 degrees. Didn't notice it much till I was in traffic and it was 95 degrees outside. A good way to tell if your pump is going out is to remove your thermostat and let it flow without restriction. This will be hard since we all know that the thermo is built into the housing. But it's not impossible. With free flowing fluid you will be able to "test" the pump to see if it's working properly.
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Old Dec 3, 2010 | 02:47 PM
  #23  
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Oldvetter: Thank You, no offense taken. I was indeed referring to the internal water pump shaft as you surmised. I'm concerned for the OP in that he's still getting air in the coolant and yet the burping doesn't seem to have stopped it, but should have by now and all of his efforts. He's replaced the thermostat already, cleaned the debris and replaced the coolant yet he's still overheating. So, either the fans aren't running when they should be or he's got head gasket issues. Fans are easy to test, turn on the HVAC and look at the fans...the right one is easy to see but the left is more difficult. If they are both found to be running, then its time to run over to a local NAPA and buy the exhaust gas test kit for the coolant ($45). If its positive for exhaust gasses in the coolant then he needs to understand what caused it.
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Old Dec 3, 2010 | 03:02 PM
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Originally Posted by dgrant3830
Oldvetter: Thank You, no offense taken. I was indeed referring to the internal water pump shaft as you surmised. I'm concerned for the OP in that he's still getting air in the coolant and yet the burping doesn't seem to have stopped it, but should have by now and all of his efforts. He's replaced the thermostat already, cleaned the debris and replaced the coolant yet he's still overheating. So, either the fans aren't running when they should be or he's got head gasket issues. Fans are easy to test, turn on the HVAC and look at the fans...the right one is easy to see but the left is more difficult. If they are both found to be running, then its time to run over to a local NAPA and buy the exhaust gas test kit for the coolant ($45). If its positive for exhaust gasses in the coolant then he needs to understand what caused it.
The fans are working properly, and I think I am just not getting enough flow from the water pump. I think if it was a head gasket it would get hot and stay hot. It gets to about 227 then goes back to 200 then goes up to 221 and it really does not make a big difference whether the engine is idling or at 2500rpm.
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Old Dec 3, 2010 | 03:05 PM
  #25  
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If the water pump is stock, then you are getting enough flow already unless there is a blockage.
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Old Dec 3, 2010 | 05:57 PM
  #26  
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This is where an infrared heat detector can come in handy. You could shoot several water coolant pieces and hoses and see if you are getting flow.
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Old Dec 3, 2010 | 11:13 PM
  #27  
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I tried everything to not have to change the water pump. Nothing worked so I pulled the water pump. I found it was leaking from the weep hole near the shaft. This caused the pump to suck air which makes the pump cavitate, therefore it overheats.
I decided it was to late in the day to work on it anymore as many of my tools are packed and also my trouble lite is packed for my move to the Phoenix area. Thank god I did not pack the wine opener!
Thanks to all who gave me the great information, this is clearly the best Corvette Forum going!
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Old Dec 4, 2010 | 08:30 AM
  #28  
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Cool that you found it leaking. When under high pressure/temperature, its actually leaking more. You should be happy after its replaced.
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Old Dec 5, 2010 | 02:52 PM
  #29  
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Glad you found the problem.

If you have been having an air leak for a while, I would change the coolant. Dexcool does not do well when mixed with air, it gets muddy brown and thickens.
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Old Dec 5, 2010 | 03:51 PM
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Originally Posted by Oldvetter
Glad you found the problem.

If you have been having an air leak for a while, I would change the coolant. Dexcool does not do well when mixed with air, it gets muddy brown and thickens.
I most certainly agree!!! Air and Dexcool do not go well together.
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Old Dec 5, 2010 | 05:23 PM
  #31  
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It's not a bad idea to change it and much will be lost with the water pump change anyway.

My research indicated the muddy brown and thickening when exposed to air occurred more because of the additive tablets that GM used to include in the DEXCOOL back in the '80s and '90s.
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Old Dec 5, 2010 | 11:19 PM
  #32  
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Default Over Heating

On Saturday morning I replaced the waterpump, pretty easy job actually. It runs now at 192 - 194 degrees. Which I guess is normal. I put new Dexcool in when I changed the thermostat so I saved what I drainded and put it back in.
My brother told me of his friend who mixed Dexcool with regular antifreeze. It clogged up his engine and radiator had to take it to the stealership to pull the motor down and clean it! Glad I did not go that!!
Thanks again to all who answered my questions.
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Old Dec 6, 2010 | 08:55 AM
  #33  
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