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08-12-2010, 10:41 PM | #1 |
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Location: Clay Center, Kansas
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Water Pump Impellers & Overheating
My towing and hauling truck is a '93 Silverado 4x4 with a 350 and auto trans. I've been having cooling system problems:
Started out with the gauge not working = replaced sending unit and wire pigtail Gauge read really low all the time = replaced instrument cluster. Gauge took forever to warm up = replaced thermostat that was stuck open. Now if I drive down the highway it'll run 210-215 empty or 220-225 pulling a vehicle (on a 100 degree day). If I let it sit and idle it'll overheat pretty quick. I checked the radiator and it had a lot of gunk in it so I replaced it with a newer one off of my parts truck which was nice and clean inside but no change. A guy at work told me he'd seen some with the water pump impeller on backwards (pump from a V belt application) so I pulled the pump tonight. But...I don't know if the impeller is on backwards or not...never really paid much attention to one before. Is this right? Any other ideas? I'll probably do a test for combustion gas in the coolant when I put it back together. But I'd think a head or gasket problem would make it overheat more on the road at speed than it does? Derek
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1999 Tahoe LT 4dr 1971 Torino 4dr 1954 GMC 100 5 window - Project |
08-12-2010, 11:25 PM | #2 |
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Join Date: Mar 2001
Location: Searcy, Ark. USA
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Re: Water Pump Impellers & Overheating
The impellar looks correct in that pump to me.
So you've replaced the radiator, thermostat. What about the fan clutch and shroud? What about the state of tune of the engine itself? How does it run? Slow ignition timing causes one to run hotter than it should. A weak engine tends to run hotter. One other thought is the wrong water pump can cause one to overheat. You mentioned it. Earlier pumps turn opposite direction to later pumps. Are you using the instrument panel temp gauge only to determine how hot it is running? Possibility the temp sender unit in the head has been changed and it's the wrong one? It has to match the gauge in calibration. Maybe some of this helps. Also a change from the 5 blade fan you have to a 7 blade can help.
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Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross Last edited by Boog; 08-12-2010 at 11:28 PM. |
08-12-2010, 11:50 PM | #3 | ||
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Re: Water Pump Impellers & Overheating
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I'll keep that in mind although I'm a pretty firm believer that the factory designed the truck to run ok and stay cool in the factory arrangement so if I can't get it to do the same I have a problem that needs fixed. After I fix the problems then I start looking into improvements.
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1999 Tahoe LT 4dr 1971 Torino 4dr 1954 GMC 100 5 window - Project |
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08-18-2010, 12:38 AM | #4 |
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Re: Water Pump Impellers & Overheating
I replaced the pump and the hottest it has gotten since is 205. I couldn't get gaskets locally to compare the pump off my truck with the pump off my parts truck so I just swapped them. I'm assuming the impeller was backwards though.
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1999 Tahoe LT 4dr 1971 Torino 4dr 1954 GMC 100 5 window - Project |
08-18-2010, 08:08 AM | #5 |
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Re: Water Pump Impellers & Overheating
Well you've made some headway with it. By the way what temp stat did you put in? I'll tell you different brand stats do not perform the same as you might expect. Have you gotten the cooling system checked for combustion yet?
There could still be a blockage somewhere. Does it have good circulation through the heater core?
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Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross |
08-18-2010, 05:14 PM | #6 | |
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Re: Water Pump Impellers & Overheating
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1999 Tahoe LT 4dr 1971 Torino 4dr 1954 GMC 100 5 window - Project |
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