Alternator woes

[Peregrine1983]

I have an older 120 amp HEHR Powerline alternator on a Westerbeke 58 in a Pearson 424. Since we bought the boat in 2016, the alternator belts have given us trouble. The alternator is armed out on the side of the engine (see pic) in a way that makes it very hard to tension the belts properly.

We often would have squealing, the smell of burning belt, and our tachometer not working until it seemed the belts would finally "catch up" to engine speed. I have tensioned and replaced these belts 3 times now. It would resolve the problem for a short while, then it always returned.

Two days ago the squealing stopped, battery charging stopped, and our tach stopped working. I removed the alternator and found that the positive bolt that the big red + wire connects to was loose inside.

I opened the alternator, used washers to reseat the bolt, and electrical tape to insulate the bolt from the housing (see pics) with guidance from the manufacturer.

I reinstalled the alternator and now we seem to at least have voltage (batteries perk up to nearly 13 volts with the engine at idle) coming from it again, however my tach still does not work, and the belts smell like they're burning - even though I tensioned them to 1/2" deflection.

I guess I need a new alternator and a new set of belts (again). Just want to hear the forums ideas for what to do though because I feel like I'm chasing my tail with this thing.

Got a quote for a new alternator from the very helpful folks at HD Powerline and I'm looking at about $850 for a new one.

Would love to hear any thoughts from the knowledgeable people on this board.

[Sailor Sailor]

Last year or the year before, I removed my alternator and took it to an automobile repair shop that rebuilds alternators. They did a great job. It solved my alternator problems and was relatively inexpensive, less than $100. You might try that before buying a new one.

[Antares]

The belt issues are frustrating as I have fought this also. I couldn't tell from the pics if you had single or dual belts but at that amperage two belts are much better. The downside is they need to be very closely matched in size. They are getting harder to find but a matched set is necessary to evenly spread the load. I have had better luck obtaining matched sets from Caterpillar than NAPA. As long as you know the width and length you can source from anyone who understands "matched set". Best wishes.

[Peregrine1983]

Thanks Sailor Sailor and Antares. Both good ideas. It is a two belt system. I didn’t know there was such a thing as a matched set.

[SoonerSailor]

See if you can get a serpentine belt kit for your engine and alternator. Big improvement especially for 100A or greater alternators.

[hjohnson]

Originally Posted by SoonerSailor

See if you can get a serpentine belt kit for your engine and alternator. Big improvement especially for 100A or greater alternators.

Poly-vee is also a good alternative, and may be less expensive. I also vote for taking it by an alternator repair shop. We have one here in Vancouver that rebuilt (and modified for external regulation) my 85A alternator, and rebuilt the starter motor for very reasonable prices.

[Peregrine1983]

Thanks all. Random question. We are underway sailing and it’s giving us trouble again.

If I disconnect the electrical cables from the alternator, but don’t remove it from the engine or take the belts off will this cause a problem?

Will completely remove it once we are in port.

[wingssail]

An external regulator will allow you to reduce the load on the belt (Balmar belt manager feature, for example). An alternator repair shop should be able to change that alternator to external regulation.

Your photos don't reveal the dual belt set-up or the belt tensioning method. Edit: I see the two belts. They don't look the same.

You need to make sure the alternator is exactly aligned with the drive pully on the engine and that the tension is sufficient. If you do have two belts of the same dimensions there should not be any squealing when it is aligned and tensioned.

My 130 amp alternator runs on a single belt and since I changed mounting bolts (to reduce movement) and began tensioning the belt properly I don't have wear or squealing.

Removing the electrical cables should prevent the alternator from functioning and it should turn freely without presenting any load on the belt. If you still have squealing maybe you have a bearing which is causing resistance to turning. Visit an alternator shop.

[hjohnson]

Originally Posted by Peregrine1983

Thanks all. Random question. We are underway sailing and it’s giving us trouble again.

If I disconnect the electrical cables from the alternator, but don’t remove it from the engine or take the belts off will this cause a problem?

Will completely remove it once we are in port.

You need to pull the field wire before anything else. It will be the small wire(s) going into the back of the alternator. Pulling the others will blow your diode packs.

[Wolfe10]

Post a picture of the belt adjuster and we can assist with "how too's" for proper tensioning.

[wingssail]

Originally Posted by hjohnson

You need to pull the field wire before anything else. It will be the small wire(s) going into the back of the alternator. Pulling the others will blow your diode packs.

Don't be frightened, it won't blow any diodes unless the alternator is running and putting out power when you disconnect it. Don't do that. And certainly, unplug the plug with the blue and white. That's the tach and field wire.

[Bowdrie]

Others have already opined on the superiority of Poly-V/Serpentine belt arrangements, so I'll not reiterate.
This may not be applicable to your situation, but something to "file away" on the use of V-belt drives.
They transfer power by friction, (friction by unit area,) and sometimes cranking-up the belt tension just adds more heat into the alternator pulley.
Just using round numbers to make a point; If engine has 4" pulley and alternator has a 2" pulley, we can expect high tensions and heat.
If the engine has a 6" pulley and alternator has a 3" pulley, the tension and the heat loading are reduced a substantial amount for the same amount of power transfer.
One of main keys to long/reliable/low stress, power transfer in V belts is to use the largest sized pulleys that are practicable.

[Emmalina]

On my old large frame Hitachi it went through a lotof belts so I bought a 220A alt of ebay for 150usd Knowing it would probably melt with my lithium's I removed the internal reg and put a balmar on the belts have been fine since. Tacho not working means you have lost your W connection on the windings !