Alternator issue

Ralph Johnstone · Jul 19, 2020

Can't start without an Engine make and model.

Ron20324 · Jul 19, 2020

first off, you probably mean the "pivot" bolt? at the 9 o'clock position?

ggrizzard · Jul 19, 2020

I think he means the "nutless" bolt at the 5:00 position. My Yanmar GM20F alternator mount has the head of that bolt on the front side and a longer bolt with a nut on the back side.
But, since we don't know what the engine model is or what a previous owner may have done in the past, it's just a SWAG.

Ralph Johnstone · Jul 19, 2020

No doubt about it, I've just got way too much time on my hands while kicking something else around on the computer.

Most likely the engine is a Yanmar by its general appearance and a 3GM by the boat size. Please, always state your engine make and model as a Pearson will contain any number of different engine makes over the years.

The question now is "which swing bolt" as that is not a name for the three supports. I'll take a wild guess and say it's the top one under the belt in the OP's picture.

Ralph Johnstone · Jul 19, 2020

You've answered your own question. The alt. casing at that point is 1/2"thick which is threaded and no nut required.

Benny17441 · Jul 19, 2020

Ok threaded casing; back to your "belt slipping" problem. Did you get it resolved? If you reach the end of the swing arm and the belt is still slipping, it either has been streched or it is the wrong size. If the belt is tight and it still slips then it is too thin for the alternator load. Perhaps an upgraded alternator or something is failing causing the alternator to tighten up. Are there any engine fluids like fuel or oil sprying on the belt? Perhaps with heat and wear the belt surface has become glassed and slick and lost its rubbery grip. The proper belt tension is attained when you can deflect the belt 1/4 inch with very light thumb pressure.

Maine Sail · Jul 20, 2020

You can just put a longer bolt through the alternator adjuster ear (should be 5/16" X 18 but may also be M8 depending upon the vintage of the Balmar.) then lock it down with a nut and locking washer. Also be sure the pivot bolt is sized incorrectly for the alternator feet. Those feet are typically a 10mm bore and some Yanmar pivot bolts are 8mm.

Also, keep in mind that your Balmar alternator is likely 100A or more. This will not work on that 1/2" belt if you cycle your batteries deeply. You will want to reduce the output of the alternator using Balmar's "Amp-Manager" (called Amp-Manager on older regulators) or the "Belt Load Manager" feature used on the newer Balmar regulators.

It's pretty hard to help you if you don't provide all the pertinent information up front..

Alternator model #
Regulator model #
Bank size in Ah's
Bank Chemistry - AGM, GEL, Flooded deep cycle, Carbon Foam AGM, TPPL AGM etc. etc..

This article may also help clear up questions about slipping arms. You may also wish to add a Grip-IT Washer...

https://marinehowto.com/marine-alternator-installation-tips-tricks/

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JoeWhite · Jul 20, 2020

Chech if the alternator bracket is cracked or broken if it causes vibration and loose belt

Mechone · Jul 20, 2020

First wrong belt ,anytime a belt goes around a small pulley (alternator ) it should be a grip notch an X in the belt number eg BX40. It won't slip and will last longer and run cooler
Put a nut and bolt thru the arm just before alternator ,this will give you something to pry against with screw driver to tighten the belt.
Or better yet convert to a serpentine belt drive for about 400.00 and forget about belt dust and slippage and changing belt

Ken13559 · Jul 20, 2020

bodaflack said:
Our solution was that after we loosened the bolt, one person lifted the alternator to tighten the belt, and then we tightened the nut. Seems to have worked so far. There is some vibration when we run the motor and we think that the alternator isn't 100% properly aligned, but it is a lot better than it was! We are getting there. How would we adjust the forward and aft alignment of the alternator?

Belt tension can be adjusted single-handed with this turnbuckle. Use a suitable length ones and expand it between Alternator pulley and crankshaft pulley to tension belt.

Ken Y

Ralph Johnstone · Jul 20, 2020

Ken13559 said:
expand it between Alternator pulley and crankshaft pulley to tension belt.

How veeeeeeeeeeeeeery nice indeed. I thought I was keeping my head above water by using a piece of 1-1/4 X 1/4" alum. flat bar to pry in the curved guide. No damage with soft alum.

This is so much simpler and effective.

Alternator issue

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