Trouble Shooting 8.1 Squeak/Squeal

I had this same issue but on my 5.0 MPI. It was not the belt or pulleys (changed them out). The noise was coming from the engine water pump. I had this issue all summer (no mechanical issue). Was about to change the pump out but then sold the boat so could not verify.
 
Resurrecting an old thread here ..I’ve been having pulley problems as of late. I replaced both water pumps in March and had both the bearings go bad in August within two weeks of each other. Replaced both pumps again. Last week I was out fueling up prepping for this weekend, and the smooth idler pulley on the water pump bracket starboard sheared right off it’s bearing. The whole belt flew right off the engine. Fortunately the marina shop had one in stock and saved my weekend. I’m hearing some clicking/squeaking from the pulleys on both engines still. Question ..with all these pulley problems am I doing something wrong? Will over tightening the belt cause bearings to go bad prematurely? Granted the idler pulley was probably just old and Im adding spares to my spares bag, but the water pumps? I didn’t think I overtightened the belt. It moves a half inch or so at the longest section between pulleys with moderate finger pressure, but with he squeaking happening still I’m concerned more pulleys are going to go. I’ll do the screwdriver test that Carter mentioned here (thanks) and try to isolate it better ..but I’m just wondering if I’m overtightening. How do you guys gauge serpentine belt tightness?

Thanks

-Mike
 
I have the self tensionioning setup so nothing to adjust. Is it possible/cost effective to convert to the self tensioning setup?

Yes I would think over tensioning the serp belt could lead to premature bearing failure.
 
Hmm ..not really sure. Do you have a link to something like that? I know they do make belt tensioner gauges ..maybe I should invest in one. I’m convinced I’m overtighteneing.
 
Hmm ..not really sure. Do you have a link to something like that? I know they do make belt tensioner gauges ..maybe I should invest in one. I’m convinced I’m overtighteneing.

The Mercruiser manual mentions a "Kent-Moore" tensioning tool. I have never used it though.

-Kevin
 
Hmm ..not really sure. Do you have a link to something like that? I know they do make belt tensioner gauges ..maybe I should invest in one. I’m convinced I’m overtighteneing.

The below diagram is for a sterndrive...but shown for the purpose of the discussion. Part 24 is the tensioner, but you would problably need other components for the conversion as well i.e. part 17 etc. Obviously you would need to confirm it could be done and the parts are for the Merc 8.1 inboard motor if you were considering going down this path.

fetch
 
The below diagram is for a sterndrive...but shown for the purpose of the discussion. Part 24 is the tensioner, but you would problably need other components for the conversion as well i.e. part 17 etc. Obviously you would need to confirm it could be done and the parts are for the Merc 8.1 inboard motor if you were considering going down this path.

fetch


I see yes ..it looks like the same water pump bracket (14) ..just a new pulley bracket (17) with a recessed area for the tensioner that attaches to it. Assuming it is the same bracket for the water pump, attaching the pulley bracket with tensioner should be a fairly clean swap out. Same bolts from the diagram. Going to look into this for sure. Thanks!
 
On my 2004 the belt tension is handled at the alternator. There is a pivot bolt and tension adjustment bracket/bolt. I just had to deal with this because my alternator locked up heating up my belt to the point it broke and also melted my grooved tension pulley. I picked up one at an auto parts store but think the proper one is the Dayco 89004 if needed (I just ordered one and will confirm).

-Kevin
 
On my 2004 the belt tension is handled at the alternator. There is a pivot bolt and tension adjustment bracket/bolt. I just had to deal with this because my alternator locked up heating up my belt to the point it broke and also melted my grooved tension pulley. I picked up one at an auto parts store but think the proper one is the Dayco 89004 if needed (I just ordered one and will confirm).

-Kevin

That’s the way mine is set up as well. It’s just a guessing game as to how tight to make he belt though (unless there’s a trick I’m unaware of.). Thought the auto tensioner Juggernaut is referring to could be beneficial.
 
8.1 belt tensioner proper tension. New belts, tighten to the point that using your thumb and pointing finger only, pinch the belts near together but not touching under moderate pressure. Firm but not hard squeeze. After a couple of hours of use, pinch again. If the belts touch, then tighten up slightly to the original pinch. That should be good from that point on.
 
8.1 belt tensioner proper tension. New belts, tighten to the point that using your thumb and pointing finger only, pinch the belts near together but not touching under moderate pressure. Firm but not hard squeeze. After a couple of hours of use, pinch again. If the belts touch, then tighten up slightly to the original pinch. That should be good from that point on.

I always used the "pinch" or "push" method. Since it is more of a "feel" to the adjustment I find it hard to explain in writing without showing but it should work fine.

-Kevin
 
Assuming that the engine's belts are within proper tension specs, I replace one belt at a time and actually "tune" them to each other. That's right - tune'm... It might sound crazy, but plucking the un-touched engine's serpentine belt will produce a tone. Pluck the same position on your newly installed belt. It will also produce a tone, but usually either lower (belt is too loose) or a higher tone (belt is too tight). Continually pluck, compare, and adjust until they both have the same tone. Start up the engine for a few seconds, shut it off, and make a final comparison.

The other thing I found is that the 8.1 OEM belts are quite prone to squeaking and clicking. I changed the belts to Goodyear Gatorback Belts and have found them to be squeak free for 4yrs now. These belts were only $17 each too.
 
Assuming that the engine's belts are within proper tension specs, I replace one belt at a time and actually "tune" them to each other. That's right - tune'm... It might sound crazy, but plucking the un-touched engine's serpentine belt will produce a tone. Pluck the same position on your newly installed belt. It will also produce a tone, but usually either lower (belt is too loose) or a higher tone (belt is too tight). Continually pluck, compare, and adjust until they both have the same tone. Start up the engine for a few seconds, shut it off, and make a final comparison.

The other thing I found is that the 8.1 OEM belts are quite prone to squeaking and clicking. I changed the belts to Goodyear Gatorback Belts and have found them to be squeak free for 4yrs now. These belts were only $17 each too.
Those Gatorback belts were the only thing that could make the squeek stop on my '01 Tahoe. I believe that they are made and/or branded as "Elite by Continental" or something along those lines. Do you happen to know the Gatorback model number for the 8.1s?
 
Had a squeak I was dealing with and swapped out the belt which stopped the squeak. According to the manual, the 8.1 has a belt tensioner pulley wheel in the middle of the serpentine route. It said turn it clockwise with a breaker bar (and 13mm socket in 1/2” drive) to loosen the pulley tension so the belt can be removed. When I did that it did not loosen the tension, only tightened the bolt. I felt having that much leverage I could easily snap the bolt so I stopped. Instead I loosened the alternator and got the old belt off - new belt on that way. Should I be concerned the tensioner is not working properly or did I do something wrong?
 
Had a squeak I was dealing with and swapped out the belt which stopped the squeak. According to the manual, the 8.1 has a belt tensioner pulley wheel in the middle of the serpentine route. It said turn it clockwise with a breaker bar (and 13mm socket in 1/2” drive) to loosen the pulley tension so the belt can be removed. When I did that it did not loosen the tension, only tightened the bolt. I felt having that much leverage I could easily snap the bolt so I stopped. Instead I loosened the alternator and got the old belt off - new belt on that way. Should I be concerned the tensioner is not working properly or did I do something wrong?
You probably should start a new thread to get better attention. I will say that the tensioner is spring loaded to maintain proper tension on the belt, if it would not move then the spring loaded base is locked up/ defective, that is why you had to go the route you took, the tensioner needs to be replaced.
 
I kinda thought that’s what someone was going to tell me. I’m gonna try the other side to see what results I get. Thanks. If the solution is not obvious I’ll start a new thread.
 

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