Alternator mounts FL120

So after a recent run back at the dock I opened the engine room hatch as usual and noticed he alternator shaking, vibrating before shutting down. We had to leave. I will be back to the boat in a few days to check it out, but I've got a feeling that maybe I have a busted alternator mount.

Question: Is a FL120 alternator mount a standard part of any kind I can order?

The lower bracket and upper strap have Lehman part numbers, 1E18 and 2M7 respectively. Bomac would be a good place to start but you may have to habe some fabrication done. If you want to PM me email or phone I’ll send a pic of the page from the manual.

2 years ago, one of the 2 bolts holding the u shaped part that hold the alternator foot sheared off on my 120. I cant say all 120 mounts are the same.

I noticed the alternator shaking and couldnt tighten the belt enough. Then it became apparent the whole alternator was cocked a few degrees.

So the mount might be OK, just a securing bolt could be the culprit.. On the otherhand, I had to left hand drill the broken bolt out, didnt have a replacement bolt so just wound up through bolting. The stock bolts just screw through the upper strap into the lower strap welded/cast on the block.

FL alternator bracket

If you remove the bottom bolt from the bracket and alternator you will probably notice that the holes are out of round, allowing the alternator to vibrate. Replace the bracket. Apparently a common problem.

Dan

I just got around to taking the alternator off. It seems that part of the mount was broke and somebody did a repair with some angle iron. The holes in the other piece are oversized.

This is the original Motorola I assume, so I’m going to try and upgrade. Pics below, comments welcomed.

Greetings,
Mr. dh. IF the angle iron "fix" is solid, I'd leave it. It appears the two aft holes (in bracket and angle iron) ARE oversize but about the same size. An appropriate nut and bolt should do there. The thing that may cause concern is the bracket to alternator attachment. At worst, you might have to have a new bracket fabricated to fit the existing threaded hole and the "fix" hole. I hope I've explained myself properly.

RT Firefly said:

Greetings,
Mr. dh. IF the angle iron "fix" is solid, I'd leave it. It appears the two aft holes (in bracket and angle iron) ARE oversize but about the same size. An appropriate nut and bolt should do there. The thing that may cause concern is the bracket to alternator attachment. At worst, you might have to have a new bracket fabricated to fit the existing threaded hole and the "fix" hole. I hope I've explained myself properly.

Click to expand...

You did, thanks. This bums me out, but I will use it as another opportunity to spend more money.

Greetings,
Mr. dh. Don't get bummed out just yet. IF you do decide to replace the alternator you may be able to fit it to the existing bracket. Again. IF you are able to securely fasten the bracket you have, to, essentially, the block AND the mounting holes for the long bolt are not worn AND the pulleys line up, you should be good to go.

Harbor Marine has a port side FL120 engine mount in stock. I’m going that route. Shouldn’t be too hard to replace.

Is there any easy way to upgrade (as in “drop in”) the stock 55amp alternator?

I went with the 95A from American Diesel.

Similar to the one you can get from Compass Marine....or new name now...and that one can have an external regulator.

the "U" shape bracket isnt used and the new one bolts into the existing holes on the block. Also you lose the wire to the oil oressure switch just below it.

Same belt.

Simple swap only a few minutes more than a direct swap.

psneeld said:

I went with the 95A from American Diesel.

Similar to the one you can get from Compass Marine....or new name now...and that one can have an external regulator.

the "U" shape bracket isnt used and the new one bolts into the existing holes on the block. Also you lose the wire to the oil oressure switch just below it.

Same belt.

Simple swap only a few minutes more than a direct swap.

Click to expand...

Thanks, I will check that out.