Water pump area sounds like marbles.

[Bill S.]

For "a number of years" I have a sound that resembles marbles rolling around in a can.
It sounds like it is coming from the water pump area. The intermittent sound always goes away in a short period of time and it can only be heard at idle. (1966 350H.P. with thermostatic spring fan clutch)
A few days ago when changing out the antifreeze and topping of the coolant with the engine idling back came the sound. This time I immediately shut off the motor and attempted to find possible looseness in the pump with the wobble method - real tight. Restarted the car and the noise vanished. This noise only occurs once in a great while. I'm baffled.
Thanks in advance.
Bill

[Don H.]

Re: Water pump area sounds like marbles.

Don't overlook the belts, I had a noise I thought was the water pump that turned out to be the belts. Don H.

[Joe L.]

Re: Water pump area sounds like marbles.

For "a number of years" I have a sound that resembles marbles rolling around in a can.
It sounds like it is coming from the water pump area. The intermittent sound always goes away in a short period of time and it can only be heard at idle. (1966 350H.P. with thermostatic spring fan clutch)
A few days ago when changing out the antifreeze and topping of the coolant with the engine idling back came the sound. This time I immediately shut off the motor and attempted to find possible looseness in the pump with the wobble method - real tight. Restarted the car and the noise vanished. This noise only occurs once in a great while. I'm baffled.
Thanks in advance.
Bill

Bill------


Usually, this kind of sound is caused by bearings that are just beginning to go bad. It could be either the fan clutch or the waterpump bearings. There might not be looseness at this point but you MIGHT be able to detect a little roughness on rotation.

[Paul D.]

Re: Water pump area sounds like marbles.

All great suggestions here. I would loosen the belts and check for roughness while rotating as Joe suggested. With tension off the pump, you will better be able to check for wobble or looseness in the shaft. Also, take a mirror and check the weep hole on the bottom of the pump for ANY sign of dampness or coolant drip. Water or coolant on the belts can make some frightning sounds sometimes. I have found that once contaminated with coolant, belts are more likely to make noise during damp and sometimes even humid weather. Chip.

[Tom E.]

Re: Water pump area sounds like marbles.

Bill,
I use an engine stethoscope to try and pinpoint noises like that. You can find them at any auto parts store for under $10. In the interim you can place the handle of a very long screwdriver to your ear and the tip on the suspected area although for the water pump area you need to really watch rotating parts ....
Tom
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[Frank D.]

Re: Water pump area sounds like marbles.

I know it shouldn't occur at idle, but I've heard that exact "marbles" description to describe detonation....
I'd also check that the timing is not too retarded... If its something mechanical whatever it is should have given it up after "years" I would think.

[Russ T.]

Re: Water pump area sounds like marbles.

Bill,

I would second Joe Lucia's comments. In my experience that sound usually indicates that the
water pump is beginning to fail, and the pump needs to be rebuilt/replaced.

Russ Trotter
NCRS #15044

[Gary J.]

Re: Water pump area sounds like marbles.

If the pump is going bad and it is the original pump, take it off and send it to Bill Mock for a rebuild. This way you will have your original pump.

[Joe L.]

Re: Water pump area sounds like marbles.

One more thing: the waterpump bearing used for all 1955-70 Corvettes with small block is fairly weak. If one gets 50,000 miles on such a bearing, one has done very well. After that, one is "living on borrowed time". In 1971 GM went to a larger bearing and shaft. They did not do this because the earlier type worked just as well.

Big blocks always used the larger bearing and shaft (although 1965-70 had a pilot shaft of 5/8" diameter).

[Dick W.]

Re: Water pump area sounds like marbles.

Old indian trick to verify source of noise. Take a long socket extension and put one end on the water pump and the other to your ear. Be careful around rotating assemblies when doing so. I was taught this probably 60 years ago before most, if any, had a stethoscope

[Richard G.]

Re: Water pump area sounds like marbles.

My bet is the pump bearing's cage is gone or mostly gone.
This type of failure can cause the intermittent noise you describe.

[Brian M.]

Re: Water pump area sounds like marbles.

If it has power steering don't rule out that pump as the source of the noise. JMHO

[Harry S.]

Re: Water pump area sounds like marbles.

If it has power steering don't rule out that pump as the source of the noise. JMHO

Brian, good thought... If it does, remove the fan belt from the P/S pump and see what happens.

[Joseph S.]

Re: Water pump area sounds like marbles.

Bill, Have you removed the fan clutch and checked for cracks in the waterpump pulley. I have seen them crack between the attaching bolt holes. This could make the sound you are hearing.