Circulating pump whine.

[Shore]

This 7.4 motor came out of a fresh water cooled boat so it had coolant all its life.It's now in my raw water cooled set-up for maybe a couple hours total.I've never had one go bad so hard to make of what its problem is.

On start-up it whines/squeeks but goes away.It has done this periodiocally over the last few start-ups.Not every time. I can touch the housing while it is running and can feel the noise.Today on the hose it was way more prominant at low idle but a little more rpm and gone.

 

[Shore]

I took the belt off and spun it by hand.It feels and spins freely and smooth but it moans...what the heck is that about?

That and the belt seemed tight but I could spin the water pump with it on.That's probably not helping but the pump itself whines.It's an easy swap but those little buggers are not cheap.

 

[Cam]

Does the pump pulley have any wiggle in it from side to side?. Sounds like it could be a bad bearing on the pulley, not allowing to pulley to be turned correctly to keep enough water coming. Also could be the belt is very old and not gripping the pulley correctly. Have you checked to be sure it is the correct belt? You should not be able to turn that pulley by hand if the belt is correctly on it. Any water coming from anywhere on the pulley or from behind it? Lots of things to check. Good luck.

 

[Shore]

The belt was spinning on the crank pulley.It looks good but is surely old.

That's the dang back belt too.Craptastic!!

 

[rnbenton]

If you can get your hands on a mechanics stethascope you will he able to hear and tell exactly where the noise is coming from.

One of the very best diagnostics tool ever envented.

Bob

 

[Shore]

I went ahead and took it off.The other two are new so might as well do this one.

I would hate to replace perfectly good working water pump for $100 over a little noise.

I see no weeping and no free-play side to side front or back on the pump.It feels like it should.

 

[stmbtwle]

"I would hate to replace perfectly good working water pump for $100 over a little noise."

That could be the best $100 you ever spent. IMO your water pump is ready to fail; only Murphy and maybe Jesus know WHEN (I'll trust Murphy).

 

[adru]

The moan you hear will eventually become a chatter and if its not leaking, it will. They usually don't fail all of the sudden but slowly wear with plenty of warning to the point of failure. If you replace it now you won't have to worry about it for years to come.