GT-40 making odd noise - marble in engine?

[pbarwick]

Sounds like at the water pump in front that there is a loose marble in it and it makes more noise as rpms increase. I am assuming that the water pump is bad? The sound is very close, but not exactly with rotation/rpm and some bounces of the marble are louder than others. I can't tell for sure if it is water pump or cam shaft below it, which would be much worse. Any help would be appreciated. I just got it out of storage due to crazy work schedule and then this happens. Engine only has 100 hours on it and it is a 2002 year motor.
If water pump, any idea on reasonable cost for repair?

Thanks a bunch for all of your ideas and opinions in advance.
Happy Boating.

[DanielC]

Take the belts off, and start the motor. You have about 30 seconds you can run the boat this way, and then it has to sit. If noise goes away, turn the alternator by hand, and listen, do the same with the circulating water pump. Both should turn freely, and smoothly. Feel for any side to side play in both these items.
The raw water pump will not turn freely. You might have to take it apart, remove the impeller, and then see how the shaft on it turns.

[horkn]

I doubt the water pump is bad with only 100 hours on it. Likewise for the alternator. Have you inspected the RWP impeller?

If you did need a new water pump (block mounted not the raw water pump) a new one is around 100 dollars.

[pbarwick]

I like the removing the belt idea

I replaced the impeller before I started engine and heard the marble.
I'll remove the belts and see what happens. Are we positive nothing bad will happen if I keep it short?
Thanks again.

[AirTool]

I replaced the impeller before I started engine and heard the marble.
I'll remove the belts and see what happens. Are we positive nothing bad will happen if I keep it short?
Thanks again.

Before you do that, you might run your engine and carefully squirt some wd-40 or LPS or plastic safe lube on your belts while its running and you might find the noise goes away. (Note I don't spray silicon - that makes them quiet then noisy later.) Often when belts get wet (like during an impeller change), they will make a marble or popcorn sound. A spray of oil will get rid of that.

[pbarwick]

belts

That sparked a memory, I do recall what looked like the belts vibrating when running, but though nothing of it. Maybe they were sticky when wet?

I'll try the wd-40 idea first, ten pop belts off second. I sure hope it is this easy.

[horkn]

It is possible the belt took a set to it during storage.

A new belt is pretty cheap, and then you can use the old one for a spare. By the time you need the spare, it should return to normal with no set to it.

[DealsGapCobra]

I just want to make sure we understand. The boat ran fine, was in storage, you go it out, replaced the RWP impeller and then started it?

I like the belt idea as it is easy to fix but am not sure I have ever heard a belt make a noise that I would describe as a marble.

I vote for belt removal and short start-up to make sure its accessory/belt related.

[DanielC]

Keep the test run without belts very short, and do not do more that one or two without a long time to cool off.

[DealsGapCobra]

I don't see any reason why there would be more than one test run for about 3-5 sec without the belts.