LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Overheating problem...

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Old May 10, 2016 | 08:38 PM
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Default Overheating problem...

Hello all. My problem is this:
I got back after being out of country for 3 weeks and suddenly I have an overheating problem. I have an 1995 LT1 5.7 6 speed with about 100,000 miles on it. Ive checked the thermostat, fan, and coolant level. The water pump was replaced fairly recently. All worked fine. Interestingly the AC works but the heating does not. Also the upper radiator hose took way longer to heat up than the lower. The right side of radiator seems cool initially, left side is hot immediately. Whats up?
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Old May 11, 2016 | 04:48 AM
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Originally Posted by LyleThe3rd
Hello all. My problem is this:
I got back after being out of country for 3 weeks and suddenly I have an overheating problem. I have an 1995 LT1 5.7 6 speed with about 100,000 miles on it. Ive checked the thermostat, fan, and coolant level. The water pump was replaced fairly recently. All worked fine. Interestingly the AC works but the heating does not. Also the upper radiator hose took way longer to heat up than the lower. The right side of radiator seems cool initially, left side is hot immediately. Whats up?
Did you bleed the system?
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Old May 11, 2016 | 08:14 AM
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The new pump might be no good. Open the radiator cap and observe if there is circulation. The steam pipe port usually flows even before the thermostat opens.
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Old May 13, 2016 | 05:02 PM
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Thank you both for responding.

Well I tried bleeding it and that did not help. I also just spoke with a former mechanic and he said the same thing about the water pump. Another mechanic said he would probably change the whole radiator. I don't know which is the problem and they're both gonna cost over a hundred, so i guess ill try to do some tests diagnosis.

Sound good/am I missing something?
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Old May 13, 2016 | 05:06 PM
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Oh, and I did observe the coolant with the cap off and it just steamed a lot and the water level just kinda went up and down. Not really side to side..
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Old May 13, 2016 | 05:16 PM
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If you go to advanceauto.com, if you spend over 100$ and use the code TRT41 it takes 40$ off. I had to replace a radiator on my previous LT1, and was able to use this code. (Radiator was over 100$) also you could do this with the water pump, however I would probably vote WP over radiator, unless your radiator is just nothing but gunked up with a fubar coolant mix.
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Old May 13, 2016 | 05:41 PM
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How recently was the water pump replaced? Is the spline drive installed? Is it worn?
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Old May 13, 2016 | 10:09 PM
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Originally Posted by LyleThe3rd
Oh, and I did observe the coolant with the cap off and it just steamed a lot and the water level just kinda went up and down. Not really side to side..
Maybe it needs to be properly filled.
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Old May 14, 2016 | 09:22 AM
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Thank y'all so much for responding.

Ill for sure try that code so thank you. Im thinking Ill replace the WP cause I did a simple test ("One way to test for a bad water pump is to squeeze the upper radiator hose when the engine is hot and idling. Careful, because the hose will be HOT! If you do not feel much coolant circulating through the hose when you rev the engine, the pump may be bad.") to see if it worked and it doesn't.
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Old May 14, 2016 | 09:27 AM
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Ive put 15000 on it since I bought it. The guy I bought it from said he had recently replaced it, but he could be mistaken or it could have been a bad part.

My main question is: If its the WP, why would it be fine/never had a problem and then the moment I get back it doesn't work?
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Old May 14, 2016 | 09:28 AM
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Ill look into the spline drive..
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Old May 14, 2016 | 12:52 PM
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Originally Posted by LyleThe3rd
Ill look into the spline drive..
In some cases the pumps spline will be slipping on the coupler causing the pump to not be able to actually flow water. A few members have had that problem.
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Old May 14, 2016 | 10:59 PM
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Sounds like you might have air in your system, but are the fans kicking on? Until I changed the fan setpoints, my car would actually run cooler in stop/go traffic with the AC on since the fans would kick in at a lower setpoint with the AC.
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