squeaky squealing sounds

i took this from my post in the electrical sub-forum since it as such is also part of the power train, and i could use some additional feedback..

i get a squeaky squealing sound from the belts on my port engine.

could it be belts slipping?

could it be a bearing about to go bust?

i installed a new alternator, however the (belts?) were making this sound before also.

Well, I'd check the tension first and if it's okay then change the belts and set to the proper tension before starting to worry about bearings and the like.

If the belt also drives the coolant pump, coolant pumps can make noise as they're starting to fail. But a squealing sounds like a belt issue to me.

PS--- You referenced this noise in your posts in the alternator discussion under electrics/electronics.* Something else to consider is the type of belt you're using.* The bottom of the belt should not be contacting the bottom of the pulley grooves.* Also, if you are running a smooth belt, switch to a toothed belt.* This may give a better grip and stop the slipping (if slipping is what you are hearing).* Or if you're running a toothed belt, try a smooth belt.


-- Edited by Marin on Friday 5th of August 2011 05:23:56 PM

the other belt drives the coolant pump (raw water pump into the heat exchanger).

the belt condition seems fine, and yes the belts are toothed.

Per wrote:
the other belt drives the coolant pump (raw water pump into the heat exchanger).

Click to expand...

*Most marine diesels are simply* marinized vehicle engines.* So they have two pumps on them.* One is the coolant (antifreeze) pump that is part of the original engine.* This pumps the coolant through the block.

The other pump is the raw water pump and this is part of the marinization kit.* This is the pump that sends water pulled from outside the boat through the various heat exchangers and then (usually) out the exhaust.

The pump I was referring to that can make noise when it starts to fail is the coolant pump, not the raw water pump.* Often the same belt that drives the alternator also drives the coolant pump, same is it did on the land-based applications of the same engine.* So if changing the alternator*belt tension and perhaps the belt itself does not make the noise go away, a potential culprit is the coolant pump, assuming it's driven by the same belt that drives the alternator.

It could be a belt slipping, or a bad bearing, if the belt tension feels right try remove the belt and spin the alternator pulley by hand
to see if it turns smoothly while the belt is off turn the coolant pump pulley by hand , wiggle it to see if it feels smooth or loose.
Good luck,
Steve W

Sounds like good advice, Marin. Belts are cheap and easy to replace. Also the tension can be critical. (as discussed in your other post) If a new belt doesn't fix the problem, then the coolant pump would be the next natural suspect.

Does the sound change as the alternator is loaded and unloaded? If not, it's probably not the alternator and maybe not the belt.

Aren't old boats fun?

I'd get a mechanics stethescope (any parts house) and find the problem, then fix it. With the stethescope you can listen to the bearing noise in the alternator, water pump and any other item you may have being driven off the belt. Then take the diaphram stick off the stethescope and listen with the open hose end to the belt near the pulleys and you can tell exactly where the noise is.

If you have a Lehman, changing the belt isn't always as easy as it could be. If you have a spare already around the cooling hose, you can put the new on in service and use the old as the spare. If you don't have a new one already threaded, then you may have to remove the coolant hose to get the new one on. This means carefully bleeding the system and all the other PITA items. (lost coolant, disposal of old coolant which is hazardous waste, etc)

Pulleys with long usage sometimes get worn so smooth that they make noise even with a new belt. In which case you can fix it by carefully sanding the pulley groove with sandpaper. Sometimes the belt is glazed smooth and service life can be lengthened by lightly sanding the belt sides.

A quick test is to start the engine, listen for the squeal and squirt a little WD40 on the belt. If the noise goes away immediately then the belt is likely the culprit. Needless to say, the WD40 will dry up after a while and the noise will come back.

Sounds like time fo a new belt. Before you install it check to see thepulleys are absolutelt clean. I have had a similar problem with my truck and the old boat. The pulleys had a glaze of black rubber dust that had been galled to their surfaces over time from heat from slipping and belt dressing (bad stuff) put on to stop the slipping. It was tough stuff to get off. I used aerosol paint and gasket remover and a wire tooth brush. be careful where you spray it. I think I read elsewhere that you recently installed a 105 amp alternator. That is probably at the ragged edge of big to be running with a single belt, particularly if the batteries are discharged. I had a 135 amp alt on my old boat with a 351 ford gasser. I could never eliminate belt slippage for long no matter how tight the belt set. I solved the problem when I converted it to dual belts.

thanks all
time for me to spend some time in the ER and hopefully find that it is just belt troubles...
btw, spoke to my mechanic also.
he did suggest to grab the pulleys on the pumps to feel if there is any looseness which could indicate bearing issues.
and he mentioned to use a bar of soap to apply the belts (similar to use of wd 40)
but i will also check the pulleys and clean them out.

ok so it was the belts, well it seemed like it was the belts....
i inspected the belts and the pulleys, grabbed and tugged at them to see if any play, all seemed fine.

i cranked her up and applied a little wd40 and the sound did seem to dissipate and i was relieved.
but i was able to identify the sound was mostly coming from the rawwater pump pulley.
while i was at it, i tested the alternator and it was putting out 14.3 volt which is good.

after shutting down, i went back down just to check if i had missed anything.
i felt the pulleys to test for heat, on the raw water pump pulley i felt heat, and more so towards the center which should not be as it should cool down from the water going thru the pump.
grabbed the pulley again to test for "play" and sure enough, i felt a slight play...

BINGO bearings in raw water pump is the culprit.

The PO had an extra raw water pump laying around in the parts bin, it is used, i am really hoping it is useable...

Good job of troubleshooting, Per.

thanks Marin, if time would permit i would have changed the unit myself but instead i put a mechanic on the job.
b
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ok maybe not quite, but probably half a boat...