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Old 04-15-2019, 06:26 PM   #1
65standard
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Can water pump go bad?

I have a 1970 with the 250 inline six. I have an engine running hot. I put a new water pump on two years ago because it was leaking. The truck sat for 3 years and now it runs hot. I put in a new 4-core copper radiator and 160 thermostat today. It still runs hot and pegs the gauge.

Can a water pump not work even though it doesn’t leak?
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Old 04-15-2019, 06:38 PM   #2
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Re: Can water pump go bad?

You might have air in the system. I usually start the truck and leave the rad cap on loose, air and water will bubble out as it heats up or until you get the air out of it. First time I did this it did the same thing. I usually use water at first to check the system then when its all good put my coolant in. The best way to fill the system the first time is thru the thermostat housing, then the block and radiator are full and it usually takes care of most of the air.
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Old 04-15-2019, 06:43 PM   #3
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Re: Can water pump go bad?

Those water pumps rarely go bad.

Its gonna get hot the first time you run it with the new t stat. Then the t stat cycles and you top off the coolant.
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Old 04-15-2019, 07:06 PM   #4
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Re: Can water pump go bad?

Okay thanks. I’ll check it out again tomorrow after a few heat cycles.
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Old 04-15-2019, 09:37 PM   #5
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Re: Can water pump go bad?

Also make sure you didn't do something stupid like put the stat in upside down.
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Old 04-15-2019, 10:10 PM   #6
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Re: Can water pump go bad?

If the pump is going bad, it’s usually not the pump but rather the bearing at the front. The symptom of that is a seepage from the weep hole on the bottom near the front of the pump. One of the things I do to help purge the air is park it facing uphill. For me it has helped every time.
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Old 04-15-2019, 10:30 PM   #7
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Re: Can water pump go bad?

Good to see you back Tony, haven’t seen you on here in a while. We’re you able to get your truck registered?
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Old 04-15-2019, 11:23 PM   #8
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Re: Can water pump go bad?

Thanks, the truck is registered and insured finally.
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Old 04-16-2019, 01:07 PM   #9
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Re: Can water pump go bad?

This happened to my water pump on a 250, it wasn't very old. I found a new pump with cast iron impeller, don't remember where it came from, though. Probably one of the chain part stores.
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Old 04-16-2019, 03:07 PM   #10
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Re: Can water pump go bad?

I changed out the water pump again and a new temp sensor and it pegs the temp gauge in two minutes or less. Ran a block tester on it and it is getting exhaust gasses in the coolant, turned the blue fluid yellow instantly. It’s a head and/or head gaskets.
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Last edited by 65standard; 04-16-2019 at 03:42 PM.
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Old 04-16-2019, 03:45 PM   #11
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Re: Can water pump go bad?

It might be time to look for a 283 or 327
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Old 04-16-2019, 04:47 PM   #12
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Re: Can water pump go bad?

Quote:
Originally Posted by 65standard View Post
It might be time to look for a 283 or 327
Stick with the 250.
Just my .02 cents.

Although, I do like the idea of a 327...

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Old 04-16-2019, 07:25 PM   #13
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Re: Can water pump go bad?

I pulled the head. The running hot issue has grown to the worse case.
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Old 04-16-2019, 07:51 PM   #14
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Re: Can water pump go bad?

That sucks about your motor. Looks like it was leaking pretty good looking at the valves. It’s hard to see from the pictures but Is the number 2 piston damaged? Looks like it’s got a gouge in it on the front side. I build slant 6’s for a living but I’ve never played with any GM 6’s. A 327 would be a fun setup. I’m glad you got it legally on the road again.
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Old 04-16-2019, 08:04 PM   #15
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Re: Can water pump go bad?

Sorry, but I can't tell anything wrong worse than a blown head gasket from the pics. What's up?
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Old 04-16-2019, 08:23 PM   #16
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Re: Can water pump go bad?

Quote:
Originally Posted by 65standard View Post
It might be time to look for a 283 or 327
It's ALWAYS that time
Sorry to hear of the troubles, but getting hot that fast and the symptoms, definitely something wrong there. The ONLY good news is it's not your water pump.
EDIT: OUCH!
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Old 04-16-2019, 08:46 PM   #17
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Re: Can water pump go bad?

Quote:
Originally Posted by jocko View Post
It's ALWAYS that time
Sorry to hear of the troubles, but getting hot that fast and the symptoms, definitely something wrong there. The ONLY good news is it's not your water pump.
EDIT: OUCH!
That’s what I thought I saw but I couldn’t tell for sure.
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Old 04-16-2019, 11:03 PM   #18
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Re: Can water pump go bad?

Quote:
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It might be time to look for a 283 or 327
Or both and build a 301
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Old 04-17-2019, 11:00 AM   #19
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Re: Can water pump go bad?

Good thing you knew how to progress through the proper diagnostics. Sometimes on here you would have been led to checking timing and carb jetting for this...
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Old 04-17-2019, 12:01 PM   #20
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Re: Can water pump go bad?

Plenty of V8’s around ! The 250 is one of GM’s greatest designs period. Chevrolet built its reputation on the L6. I installed a 292 in place of a 250 once thinking it would be an improvement, big mistake ! 250’s Rock....
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Old 04-17-2019, 06:09 PM   #21
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Re: Can water pump go bad?

I’m saving the 250 for now. I just want to drive this truck. Maybe swap out to a big block in the winter. Good running 454’s are easy to find around here. 327’s not so much.

The head checks out good. No cracks or warping. Just going to freshen it up and put it back on.
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Old 04-17-2019, 08:10 PM   #22
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Re: Can water pump go bad?

Sorry to see the problem. Wanted to share that I once had an over heating problem. it was fine at low speeds, but when you got up to 50-55 it would start to over heat instantly. I suspected a bad hose collapsing because the water pump was brand new. Turns out the impeller was slipping on the shaft when I got up to high speed. Just in case anyone has this issue. Good luck with the engine.
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Old Yesterday, 01:00 PM   #23
65standard
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Re: Can water pump go bad?

The head and block are cleaned up and ready for the new gaskets.

Yes, the head gaskets was leaking, but I think this was a big cause of my overheating problem.

This is the lower hose.
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Old Yesterday, 01:01 PM   #24
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Re: Can water pump go bad?

Ready to assemble it.
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Old Yesterday, 03:48 PM   #25
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Re: Can water pump go bad?

Quote:
Originally Posted by 65standard View Post
The head and block are cleaned up and ready for the new gaskets.

Yes, the head gaskets was leaking, but I think this was a big cause of my overheating problem.

This is the lower hose.
Did you pull that hose off your drier vent? JK but what in the world is that?
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