Water pump or sending unit? - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 03-25-2012, 09:24 AM   #1
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Default Water pump or sending unit?

Black Betty just stared running really hot. Would hang out around 250- 260, and now it pegs at 280 after changing the thermostat yesturday. All the limp mode stuff comes on, tells me a/c is turned off, then to idle the engine then to turn it off and it reduces power. I cant find the "weep" hole in the water pump. Could i have a massive air pocket in the system? bad water pump, or sending unit?
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Old 03-25-2012, 09:44 AM   #2
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if you have a ir temp gun you can run the car and shoot the neck where the thermo is and see if the gauge is accurate. if it is sounds like water pump
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Old 03-25-2012, 10:04 AM   #3
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Its possible you have an airpocket, or a thermostat that is stuck closed. Did you test its operation prior to installing it?
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Old 03-25-2012, 01:07 PM   #4
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sounds like intake gaskets to me. u need to pressure test the system first. letting the temp get so high, u are going to be doing head gaskets if u keep that up...
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Old 03-25-2012, 01:10 PM   #5
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sorry, just re-read your post. now that i know it'* a northstar and not a 3800...? good luck...
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Old 03-25-2012, 01:22 PM   #6
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If i remember right the northstar has the water pump running of the cam belt on rear of the motor(tranny side). There kinda of a pain to change.
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Old 03-25-2012, 06:05 PM   #7
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Ok, just checked the housing with the IR thermometer...one side 198.6, other side 161, with the gauge pegged at 280. After breaking open the cooling system to replace the thermostat do i need to extract the air out? Im still thinking its a bad sending unit too. Have to hunt that down, LOL
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Old 03-25-2012, 07:12 PM   #8
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if you measure less than 200 there its running at the normal temp and you have a gauge or sender problem
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Old 03-25-2012, 07:58 PM   #9
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I'm leaning towards a sender. If it were a gauge problem the limp mode wouldn't activate. Just my thinking though...makes sence to me, LOL
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Old 03-25-2012, 09:00 PM   #10
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Quote:
Originally Posted by Mike1995 View Post
Its possible you have an airpocket, or a thermostat that is stuck closed. Did you test its operation prior to installing it?
I agree
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