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#1 |
Registered User
Join Date: Apr 2015
Location: East Tn (In the heart of the Smoky Mtns)
Posts: 1,868
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Can the impeller on a water pump go bad?
I had a recent thread about having a “Temp Gauge Issue”.
After a process of elimination, I’ve Figured out that the coolant is not circulating. The water pump is probably 25 years old. In the the past Five years the truck has sat ALOT. I’d start it up and toy with it, but in those 5 years I’d say I put less that 500 miles on her. A mechanic friend of mine said it’s possible that the impellers went bad. After thinking about it, the temp gauge started showing in the “High Normal” range, then Went to showing hot all the time. I went the rout of “it must be the t-stat”, then “It must be the Sender”, then “it must be the gauge”, never even considering the water pump. As I’ve said in my other Thread, the engine runs like a top. |
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#2 | |
Senior Member
![]() Join Date: Apr 2013
Location: Podunk, Texas
Posts: 748
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Re: Can the impeller on a water pump go bad?
Quote:
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"It is hard to search for a black cat in a dark room, particularly if it is not there. Especially if this cat is smart, brave, and polite." Sergei Shoigu, Russian Minister of Defense |
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#3 |
Who Changed This?
![]() Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,388
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Re: Can the impeller on a water pump go bad?
Lots of things it could be, in order of my experience:
1. Radiator clogged 2. Stuck thermostat 3. Collapsing lower radiator hose 4. Blown head gasket Does it do it at idle? Bad fan clutch, or insufficient air flow. Does it do it at speed? Clogged radiator. It is entirely possible that the gauge or sender (or the wiring/circuit board) have gone bad. If the truck has sat a lot, it is entirely possible that the impeller is rusted away enough for this problem. I chased my tail on my truck for awhile and discovered that it liked a high-flow thermostat...after replacing the fan clutch and making a fan shroud to fit the larger fan that I had installed. I'd recommend cleaning the cooling system with some common product and then taking the radiator to a shop if the flow still looks low. Maybe take the t-stat out first as an easy check, though. If you're handy, you can just throw a water pump at it for grins. They aren't that expensive. I personally like to make certain that I locate the true problem. When I worked as a mechanic, I wanted to be proud of the correct diagnosis, instead of throwing the customer's money at it. They don't like people guessing with their money. I know I sure don't.
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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#4 | |
Registered User
Join Date: Apr 2015
Location: East Tn (In the heart of the Smoky Mtns)
Posts: 1,868
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Re: Can the impeller on a water pump go bad?
Quote:
, it’s got a fairly new radiator, new T-stat, New sending unit, the system was flushed about 5 years ago, but as I said before has had very little use. It starts up fine then the gauge just climbs. As my friend said, it’s not circulating. I’m going to put the new water pump in and hope for the best. In the mean time any insight is encouraged. |
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#5 |
Senior Member
![]() Join Date: Mar 2003
Location: Colfax-California
Posts: 8,522
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Re: Can the impeller on a water pump go bad?
I have seen them completely rusted through after sitting for quite a few years. Fill it up and pull the heater hose that feeds the core and see if there is any flow
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#6 |
Registered User
Join Date: Jul 2018
Location: Catskill Mountains,NY
Posts: 8,471
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Re: Can the impeller on a water pump go bad?
YES the impeller can rot away if it's a stamped steel unit. I had a jeep that was overheating. Checked everything when I pulled the water pump there was bits left of the impeller. Changed it out truck ran like normal again
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Mark 72 c20 custom camper Husky edition, 66 SS396 Chevelle 1964 Hawk, 63 Avanti,62 lark 1969 AMX , 1968 c20 stepside ,85 K20 1977 Suburban sold 68 anniversary. |
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#7 |
Registered User
Join Date: Apr 2015
Location: East Tn (In the heart of the Smoky Mtns)
Posts: 1,868
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Re: Can the impeller on a water pump go bad?
I have another water pump that I’m going to change out in the morning. I really hope this is the end of the saga.
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#8 |
Post Whore
![]() Join Date: Feb 2016
Location: Portland Oregon
Posts: 11,111
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Re: Can the impeller on a water pump go bad?
It is pretty easy to tell if you have a bad impeller. Drain the coolant until it is 6 to 8 inches down in the radiator. Then start the engine and let it get hot. When it warm enough the thermostat will open. The coolant level will drop and you will see water flow from the tubes in the radiato. The water should be flowing strongly from the tubes not just dribbling out. . It should get stronger when you rev the engine.
A simple check before you pull the pump.
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Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. ![]() RIP Bob Parks. 1967 Burban (the WMB),1988 S10 Blazer (the Stink10 II),1969 GTO (the Goat), 1970 Javelin, 1952 F2 Ford OHC six 4X4, 29 Model A, 72 Firebird (the DBP Bird). 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377 |
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#9 | |
Registered User
Join Date: Apr 2015
Location: East Tn (In the heart of the Smoky Mtns)
Posts: 1,868
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Re: Can the impeller on a water pump go bad?
Quote:
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#10 |
Registered User
Join Date: Apr 2015
Location: East Tn (In the heart of the Smoky Mtns)
Posts: 1,868
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Re: Can the impeller on a water pump go bad?
So I went and drained some coolant and started it up. The gauge did the same, and I could feel the upper hose get hot when the T-stat opened. Looking down in the Radiator there was no coolant moving. So I’m going to say it is a bad water pump. I got it ordered, and just have to wait for it to come in.
I’ll either be up and running this afternoon or tomorrow morning ![]() |
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#11 |
Registered User
Join Date: Apr 2015
Location: East Tn (In the heart of the Smoky Mtns)
Posts: 1,868
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Re: Can the impeller on a water pump go bad?
So I put the new pump in, and everything works, except my gauge, still.
I think I have to go with the Auto Wire sending unit, because the pegged out gauge drives me crazy, especially when I know everything is working correctly. Next, I have to figure out the Vapor Lock issue I’ve developed |
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