Alternator belt alignment

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C

Chief

A few months back I posted a ton of requests regarding replacing my alternator on a 89 Cat 30. I had planned on up-grading to a slightly larger (72 amp) and adding external regulation because of my new AGM batteries. Since some PO's had done some funky re-wireing nothing seemed like it should have been. I enjoy doing my own work, and usually I am pretty comfortable with electrical projects. The final suggestions from the group, was bite the bulllet and pay the yard to do the job right. I asked the owner if he minded doing the job with parts I already purchased. he replied it would not be an issue, and would do the work after I splashed. I had removed the old alternator over the winter to make sure that I have an exact replacement. I did manage to find an ideal replacement, a Leece-Neville marine, with external regulation that has the exact same footprint as the previous Motorola. When I decided to have the yard perform the work, I replaced the old alternator and reconnected it. I ran the engine prior to splashing, and it ran fine after I went into the water. What I did notice is that the belt alignment is not correct. I do not remember any shims when I first removed the alternator. So far the belt has not come off, but I am going to give the yard 10 days to do the work, then I am leaving for my home port. I got splashed much latter in the season then I had planned, mostly my fault. However here in the norteast we have a short season anyway, I do not want to spend it at my winter yard. I need to correct the alignment if I plan on leaving before he gets to the work order. Does anyone know how to place the belt back into the proper alignment. I have to motor for two hours to get home, and I cannot take a chance with the belt the way it currently is.
 
Aug 9, 2005
772
Hunter 28.5 Palm Coast, FL
You may have to use wshers as shims or...

you may have to grind the mount or the arms on the alternator to fit. Just take your time and ues a ruler and the old eyeball to check the alignment. Good luck.
 
C

Chief

Original alternator

The alternator I re-installed was the one that just came out. There has to be an easier way as this alternator has been on the boat since 1989. Either I miised some shims or washers when I briefly removed it to match it up, or there is a way to adjust using the top and bottom bolts. I could understand grinding etc, if I was trying to replace with a Balmar or other product not made for this engine.
 
Feb 6, 2006
249
Hunter 23 Bay Shore, LI, NY
Chief, you said it yourself:

If the original lined up OK before you removed, and now it doesn't, then you have either lost/misplaced a spacer or you have re-installed it wrong. Perhaps you put it behind a bracket when it should have been in front, so moving it back? We wern't there, so we can only make wild guesses! Perhaps it was always out of alignment and you never noticed? Check the belt for one-sided wear.
 
D

Don

Belt alighnment

What you probably didn't notice on installation, the old alternator used a 3/8in mount bolt. The LN takes a 7/16in bolt. If you remove the adjusting arm, you will notice the alternator will wobble on the bolt. When tightened down, the alternator will cock to one side and eat the belt. You have 2 choices. Drill out the mount bracket and use the proper size bolt. But now you can't go back to the OEM alternator. OR, find a bushing or go to a machine shop and have one built that goes inside on the alternator and use the existing bolt (my recommendation).
 
C

Chief

Alternator

Thanks to all who took the time to respond. Th digital camera is currently OOS, actually that is our mothers day/fathers day gift to each other. Therefore pictures are out of the question. The old alternator was removed for around two weeks I never attempted to mount the Leece Neville, however the bolts are a dead on match. The original belt (I have owned the boat for 4 years)looks like new, so it has not been wearing unevenly. I have worked on virtually every other part of the engine, and as soon as I replaced the alternator I knew something was not right. I have checked pictures on the C36 website, and I replaced the alternator back exactly as the pictures show. My only guess is that there were shims somewhere, and they dropped before I noticed them. I also have the Universal service mannual, and it states "tighten drive belts by applying pressure to the alternator front housing ONLY". "Do not apply pressure to the rear housing or stator". I am not sure what this means, or if it has any bearing on the issue at hand. The only two bolts are on the front of the alternator. Tightening them does not affect the bellt alignment. If one were to use shims, where would they be placed? Currently the alternator seems to be leaning backwards. Hopefully, the yard will get to the job by the end of the week. At that point it will be there responsibility to get things right.
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Out of alignment how

There are a few different types. The rotational axis of the alternator and crankshaft are not parallel The front edges of the alternator and crankshaft are not lined up "along the belt" or the belt runs at an angel between them and not straight. From your "leaning back" statement I'm thinking the former. There are sometimes shims that look like a metal tube (bushing is the technical term). Try this loosen the bottom bracket and see if you can get it to line up. There may be a bushing in the bilge under the engine. The adjusting arm may go on the other side of the alternator casting for the bolt The comment on tightening is for when you are applying pressure with a big screwdriver to tighten the belt. You want to keep the place you apply pressure as close to the front as possible to prevent setting the alternator axis out of parallel with the crankshaft axis.
 
J

John

Hi chief

Hi chief ive seen 3 88 and 89 C30s with the alt off about3/8 " mine was one of them .I think catalina moved the pully back to clear the moter cover.I rebuilt my alt last year and the guys at the shop gave me a thin pully that could ride in line with the main pully, it worked great.I had my boat for 6 years and i never noticed the pullys being off.I change the alt bracket at the same time. John
 
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