C1 water pump pulley wobble

[Joe P.]

I have developed a wobble in the water pump pulley that wasn't there a few months ago. I also noticed a good section of the belt was missing on the narrow end. I checked some videos that i had taken in August and there was no wobble back then. I had the water pump rebuilt 12 years ago and replaced the pulley, and fan clutch at the same time. I am running a 5 blade fan.

I took off the fan and with the pulley attached, i spun it by hand and the wobble is still there. I put the pulley on a flat surface and tried to measure the height around the pulley and didn't see any real noticeable difference, with a ruler (Wide side up).
The pulley on a flat surface seems flat to me ( Wide side down)

I did find no noticeable play front to back in the water pump shaft, but did notice the i was getting a small amount of side to side play on the shaft.

Should there be any play here?

During my trouble shooting, I also corrected an alignment issue, that has been there for probably 12 years. The generator pulley was ahead of crank and water pump pulley by 3/8 ". The generator pulley bracket was on upside down. The crank and water pump pulley were always aligned.

My conclusion is that the water pump bearing is starting to go, probable caused by the generator pulley misalignment and stress of the generator pulley on the water pump pulley. This also cause the belt to start failing.

Any thoughts on rebuilding the water pump or perhaps a modern replacement that may help with cooling?

[Joe R.]

Re: C1 water pump pulley wobble

Please go to the bottom of this thread and read Similar Threads. Your answer is there as early as last week.

JR

[Joe L.]

Re: C1 water pump pulley wobble

I have developed a wobble in the water pump pulley that wasn't there a few months ago. I also noticed a good section of the belt was missing on the narrow end. I checked some videos that i had taken in August and there was no wobble back then. I had the water pump rebuilt 12 years ago and replaced the pulley, and fan clutch at the same time. I am running a 5 blade fan.

I took off the fan and with the pulley attached, i spun it by hand and the wobble is still there. I put the pulley on a flat surface and tried to measure the height around the pulley and didn't see any real noticeable difference, with a ruler (Wide side up).
The pulley on a flat surface seems flat to me ( Wide side down)

I did find no noticeable play front to back in the water pump shaft, but did notice the i was getting a small amount of side to side play on the shaft.

Should there be any play here?

During my trouble shooting, I also corrected an alignment issue, that has been there for probably 12 years. The generator pulley was ahead of crank and water pump pulley by 3/8 ". The generator pulley bracket was on upside down. The crank and water pump pulley were always aligned.

My conclusion is that the water pump bearing is starting to go, probable caused by the generator pulley misalignment and stress of the generator pulley on the water pump pulley. This also cause the belt to start failing.

Any thoughts on rebuilding the water pump or perhaps a modern replacement that may help with cooling?

Joe------


I agree with JR; I think that you'll find a lot of information relative to your inquiry in the archives as it's been discussed many times.

I'll add one thing because I don't know if it's in the archives: the 1955-70 small block waterpump shafts were "weak". These shafts were 5/8" from end-to-end. For 1971 Corvettes GM went to shafts that were 3/4" from outer end through the bearing. They didn't do this because the 5/8" shafts worked just as well. However, these shaft/bearing assemblies cannot be retrofitted to 1955-70 waterpump castings. The 1971 pumps cannot be retrofitted to 1955-70 without also changing the waterpump pulleys and fan clutch.