Ear piercing screech

[Merc4ever]

I pulled my boat out of winter storage (Merc 4.3) fired it up and in the front of the engine I hear this loud screech that hurts my ears and is rythmatic with the turning of the belts.

New altenator last year
1989 water pump?
Belt tension seems good
It stays cool and everything is working including PS which is full of oil to the propoer level. I noticed a little rythmatic squeek last year at the end of the season but now the sound is unbearable and it makes your ears ring.

 

[Don S]

Re: Ear piercing screech

Follow the sound and find out what part is making the noise.

 

[Merc4ever]

Re: Ear piercing screech

Sounds pretty loud near the pump but it's hard to tell for certain and I don't want my head or limbs to get caught in the moving parts. Is that normal? Can I keep using it like that?

 

[paultjohnson]

Re: Ear piercing screech

Take your belts off one at a time and start it briefly. When the noise stops, you will know whats making the noise. Yes, its normal for a person to not want to get their head or limbs caught in the moving parts of a running engine. Of course you can keep using it like that, tho you may end up broken down some where, and probably greatly increase the overall cost of repairs. but you CAN do that if ya want.:facepalm:

 

[Samjo]

Re: Ear piercing screech

Get a piece of hose about 3 foot long, and use it as a po-man's stethoscope. You can hear through the hose, and it'll help you locate the squeal without getting your head so close to the spinning parts of the motor.

 

[Don S]

Re: Ear piercing screech

When a belt makes that much noise, it's either loose, or something is not turning but the belt is. Either way, no one sitting here at a keyboard can see or tell you what it is, unless we make a lucky guess. But no one will know until you look and listen and see what is going on. We can't.

If you can't figure out what is making the noise, you need to find a qualified Mercruiser dealer.

 

[Merc4ever]

Re: Ear piercing screech

Oddly enough I removed all the belts and turned the water pump, then the altenator, then the power steering pump, then even the engine...ugh, all with no squeeks or squeels.

My altenator belt was a little loose but it's in the tightest setting so maybe it's stretched and causing the noise from being too loose. I will get new belts tomorow and update with the results.

 

[Merc4ever]

Re: Ear piercing screech

Uh scrap that I just measured its maybe 44 and 1/8 and the new one says 44 inches long. Can't be streached much maybe my deflection is off. I put light pressure with my finger and measure around 3/4 inch. Does that sound right?

 

[joncrisler]

Re: Ear piercing screech

I have had this sort of noise happen to me twice- one time it was a engine water pump, the other time it was a gimble bearing. (Alpha 1 drive). You need to rule out slipping belts first.

 

[Merc4ever]

Re: Ear piercing screech

It's not the gimble bearing because it's up in the front so I guess tomorow I will start it without the altenator belt and the noise should be gone. Then I'll have to figure out what's wrong.:facepalm:

 

[Silly Seville]

Re: Ear piercing screech

FYI, when you spin a pulley by hand, you cannot replicate the speed and pressure that a running engine puts on the shaft bearing.

 

[cr2k]

Re: Ear piercing screech

Happens a lot, usually a slipping belt and usually the alternator as it has a big load on it after starting.

 

[Merc4ever]

Re: Ear piercing screech

I found the problem!
Dumb Dumb Dumb :facepalm:

The belt was in the middle water pump groove it's supposed to be in the one close to the engine block. Now I have lots of adjustment and it's as quiet and smooth as new!

Good lesson to all you dummies out there like me! :facepalm:

Thank's to everyone for all the good suggestions!

 

[Samjo]

Re: Ear piercing screech

If the belt has ever been run loose enough to squeal, then you'll probably have to replace that belt to keep the noise from coming back. The fact that you stated that it was already at it's maximum adjustment, makes me think that it's been slipping.

Once a belt starts slipping, it will overheat it, and harden it, and it wont have the grip it used to have. You might see the sides of the belt are shiny. They shouldn't be.

You've got to identify where the squeal is coming from, to fix it, but my best internet guess is the belt.

 

[Samjo]

Re: Ear piercing screech

Hey....no fair!

You posted that the problem was solved, at the same time I was posting my solutions!



Glad you got her fixed.

 

[Merc4ever]

Re: Ear piercing screech

Thanks, Samjo