Belt/pulley squeal when starting - 496 HO
 

My starboard side motor has had a squealing noise for the past few weeks and I can't seem to figure it out. It goes away after the engine has been running for a few minutes. I changed out the serpentine belt and no difference. I checked all the idler pulleys and those all seem ok. Any ideas? I'm thinking either the Alternator or the water circulating pump but how do I know for sure? Also, since this is a twin engine boat, the power steering is run off of the port motor. So, on the starboard motor what is down there in place of the power steering pump? Or, is there a pump there but just not hooked up or utilized?

You probably already know this but just in case........

To check a pulley or the alternator/pump bearings, use a long screwdriver with the engine idling and rest the blade on the housing of the pulley. Put the handle end up against your ear and listen. The screwdriver acts as a stethoscope and if the pulley bearings are shot, you will hear the difference as the noise travels up the screwdriver to your ear. Compare a couple of pulleys with each other or with the other engine.

Can be a bit hard to do sometimes because you don't have much space in the engine bay but if possible, it's a good simple test. Bearings can be rough and noisy then free up after turning a little, hence the intermittent nature of the noise.

RR

Thanks, I did not know that trick... I'm not sure if I'll be able to get to all of the pulleys on my boat using this method unless the screwdriver is VERY long. Would anything metal work?

Basically yes, but you can go to most any auto parts store and buy a stethoscope for not much money. Then can listen to all kinds of scary noises. Jk
Nice thing with a screwdriver is it has a handle to rest against your ear.

Thanks! I ordered a mechanics stethoscope on Amazon (had great reviews) and will be here tomorrow. Hopefully that will pinpoint the issue.

Best advice for any noise to pin point is a real doctors stethoscope. I have been using this method for 20 years. I can find exactly where the noise coming from. They cost generally a 120 to 400 bucks for a really good one.

They really isolated the noise. I also use it to see if fuel injectors are pulsating and you can actually hear the fuel flowing thru them if you are using a high quality Doctors stethoscaope. I also use it a lot for pulley / bearing noises, outdrives, engine knocks, valve train noise and even electric fuel pumps. You then can tell a good electric fuel pump from that is going out or restricted.

For the money one of the best tools I have every bought to save a whole lot of time and to pin point exactly noise problems.