Belt Squeal after alternator change... HELP

[sdleo26]

Due to a failed alternator, I had to swap in a new one and now cannot stop belt sequel. The motor is a 5.7 MAG MPI in a V-drive configuration. If I spray belt conditioner it goes away; I can run the motor under load with no issue and no squeal after spraying the conditioner, but once I let the boat sit or come back the next day, the sequel is back. Tried 3 different belts, but it still exists.

There are no sings of belt damage. I took a straight edge and the alternator pulley is parallel, however, it is set back from the crank pulley by almost a 3/16" - 1/4". My Starboard motor has the original alternator and is also set back from the crank pulley, but not as much, maybe an 1/8".

I bought two alternators as I wanted one for a spare; they both exhibit the same behavior. I ordered one from DB electrical and the other one from a local Mercruiser dealer, but that one still looks like an aftermarket unit (Arco).

I am trying to find a shim or a wider spacer for the alternator shaft in order get the pulley closer in line with the crank pulley, but have been unsuccessful. The alternator brackets dictate the position front to back, so the only choice is to shim the pulley shaft or grind down the ears where it swivels at 12 o clock to bring it forward; did not want to do that just yet however.

I threw the original alternator out, so before I take the unit off of the other motor to measure the dimensions, does anyone have any words of wisdom? This is driving me crazy to say the least.

Thanks and Regards

 

[Bt Doctur]

Is this a "V" belt or serpentine
The threads in front of the pully the same length

 

[sdleo26]

Serpentine, I will have to look, not sure about thread length . Be back down at boat tomorrow.

 

[Espos4]

As you may have learned, never discard any old parts too soon.

If you still had the original alternator, I would suggest using the original pulley on your new alternator.

How about swapping the pulley from the other motor. If the squeal stops, maybe you could take some measurements from the "good" pulley to see how much of a shim you need.

As a side note, if the alternator shaft is tapered, I don't think you would be able to use any type of shim.

 

[sdleo26]

Yup, learnt the hard way, and I usually never throw out anything, but was in a rush, oh well. Shaft is not tapered, thankfully. I found some spacers that might work on aspwholesale.com ... 60 cent part, probably pay $10 in shipping ... ugggh

 

[CliffA]

first off make sure you have the correct tension on the belt.....also make sure that all of the pulleys that the belt runs in/over are clean and dry and are not rusted.....and don't use any more 'dressing' on the belt....in my experience it just makes things worse by attracting dirt and glazing the surface of the pulleys....

I fought the exact same thing on an old Jeep Wrangler when I replaced the power steering pump......I worked MANY hours trying to get the belt from squeaking because the pulley on the new pump was slightly out of alignment with the other pulleys......

bottom line your going to have to get the pulleys to align by doing what ever it takes to stop the squealing.....that can include shims, moving the pulley on the shaft slightly, bending mounts, etc......

cliff

 

[Ididntdoit]

Just replaced my alternator too.....bought the new one at and "old school" auto electric place..... they swapped the pulley as the new unit one was slightly different.......and your right, it had a spacer too....

 

[CliffA]

Just replaced my alternator too.....bought the new one at and "old school" auto electric place..... they swapped the pulley as the new unit one was slightly different.......and your right, it had a spacer too....

not to derail the thread but is the new alternator you bought from an auto electrical shop ignition protected?......

cliff

 

[Ididntdoit]

not my first rodeo, but thanks for asking....yes, they are right in ft lauderdale and do marine and industrial.....picked up new group 31 batteries too - same manufacturer as wm but half the price....

 

[CliffA]

not my first rodeo, but thanks for asking....yes, they are right in ft lauderdale and do marine and industrial.....picked up new group 31 batteries too - same manufacturer as wm but half the price....

I figured as much.....just like to verify just in case someone that doesn't know any better would read this thread and think it is OK to use an alternator designed for a car engine....

cliff

 

[Jetgod]

I had the same problem on my 2000 310 DA 350 mag mpi's. The only way to fix it is to ensure all pulleys are on the same plane. I accomplished this by using washers for shimming, carefully bending some brackets, etc till all pulleys were in perfect alignment. Then make sure the belt is tightened just the right amount.This takes some going back and forth but is imperative to have the right tension. Too tight will cause it to squeal as quick as too loose. Never spray belt conditioner or anything else as that just confuses the issue. I was so happy when I sorted this out. Good luck.

 

[sdleo26]

I thought I would give an update. First, thank you to everyone who replied, it is much appreciated. I finally got the belt to stop squealing.. I cleaned all of the pulleys and the belt with mineral spirits and that did the trick. The alternator pulley is still offset, but it is quiet. I thought I would try cleaning ups the pulleys before shimming the alternator shaft. The other motor, as I mentioned, is also offset, slightly less; but still offset. In addition, I also bought continental elite belts, which are the new gator back belt that Good Year used to offer (they were bought out).

For anyone with a 5.7 in this configuration (i.e., V- drive) the belt cross reference is 4060875. They are $29 compared to $80 from Mercruiser; more than likely a Dayco anyway. These new continental belts seem to be much better made and are less prone to being noisy, not as temperamental I would say.

This forum has been such a great resource for me over the past 6 seasons. I have learned a great deal to say the least. For the thread "where has this forum gone".. the answer is nowhere, still lots of great info and people... Happy boating everyone!