Drive belt woes

[mainesail]

A few thoughts here:

#1 You can not use a split washer on a slotted alternator adjustment arm without a flat washer between it and the arm. It will do exactly what is shown. Also always be sure that the washers bore size/ID matches the bolts OD.

#2 The flat washer that compresses on the slotted adjuster arm should ideally be an extra thick fender washer with an OD that closely matches the width of the arm. McMaster Carr is your friend in this department. Standard fender washers need not apply here and doubling them up is NOT the same as one thick washer.. I generally try to use fender washers that approach thickness as the arm material.

Extra Thick Fender Washer:


#3 A v-pulley's belt width can't be adequately measured across the top of the V then compared to another v-pully. The depth to which the "V" is cut in the billet steel can make one pulley wider at the top, or narrower, but they may both still be a 1/2" or 13MM belt or a 3/8" or 10MM belt. This is why the same belt may ride higher or lower in the alt pulley than it does in the crank. Most Universal Diesels shipped with 3/8" or 10MM belts but this engine has been converted to dual v-pulleys so all bets are off. There are no in-between sizes of v-belts for 3/8" nominal or 1/2" nominal.  They are standardized such as; 3L (3/8"), 4L (1/2"), 5L (5/8") other types such as cogged, wedge type, cogged-wedge etc. are still a standardized width. Metric belts are also standardized for width such as; SPZ (10MM), SPA (13MM), SPB (17MM) etc...

#4 The alt regulator used on Paul's boat has no way to limit alt output for safely matching it to a safe belt load. It is not a Balmar regulator but rather an old Heart/Xantrex that lacks the ability to limit/de-rate alt output. Any well built performance alternator, such as the CMI/Grasser alt on Paul's boat, will pump out more than it's face value "nominal rating" when cold and even when fairly warm too. A 1/2" v-belt is pushing it's limits at 85-90A let alone anywhere close to or over 100A. Unless Paul can find a matched pair of v-belts, and install them, this regulator is less than optimal and belt wear and slippage will continue to be problem.

#5 The only good way to measure a v-pulley is with a v-belt sheave gauge. Of course the difference between a 3/8" pulley and 1/2" is easy to see with trained eyes, it may not be for one who doesn't do this every day. Please do not get hung up on sheave angles unless it is a rather gross mis-match. Alignment, sheave condition, belt tension and not overloading the belts capabilities are what matter most. The engine manufacturers could care less about sheave angles, and almost all of them have sheave angle mismatches between crank and alt, by a few degrees. I have measured these mismatches on everything from Yanmar, Universal, Westerbeke, Cummins, Cat, Beta, Nani and others. If your pulley on an alt actually matches your crank this is certainly optimal but don't count on it even with a factory installed alternator. The difference an exact sheave angle match provides is considerably less than the other mentioned items.

#6 On Paul's engine he can't do this, just a poor design when dealing with higher output engines, the arm tension bolt should be long enough to get a nut & washer on the back side. The belt tension is adjusted using the tapped ear in the alt and then torqued properly. You then install a washer (the aluminum is soft) and a nut on the back side and torque it.. I prefer nylocks for this use but a split is fine too. If your alt is getting hot enough to melt a nyloc nut, the nut is not your issue. The nylocs I use have a safe working range up to 140C or 284F. Of course 284F is far from where the nylon would melt, this would be approx 425F. If the adjuster ear is getting anywhere close to 284F (this means a diode temp of well over 320F) you have a MAJOR problem and your alt will not last long at all. You can always slide a split washer in there too but it is really not necessary if you're using a nyloc..

[KWKloeber]

PS, I have also gotten extra-thick flat and fender washers from Grainger, but that's because it was around the corner and I was already picking up an order -- and it saved the shipping from McMaster.

https://www.mcmaster.com/#flat-washers/=7cd761b2fee5425cb0cce6868a7e131ejc28h5li

https://www.grainger.com/category/flat-washers/washers/fasteners/ecatalog/N-8ogZ1yzaubuZ1yzauakZpgnZ1yzauc8Z1yzauaj?searchRedirect=flat+washers#selectedFilter=ShopBy-nav

k

[britinusa]

I found the thick fender washers at Lowes.

thanks guys.


Paul

[prh77]

Another potential issue; is the alternator putting out mucho amps due to battery or regulator issues. I remember discussions about how the single v belt gets overloaded as you go above 90 amps or so with the alternator installation.

[KWKloeber]

What belt were you running?

Paul, replace the belt with a Dayco Top Cog construction (Gold if you can find the size) if that's not what you're running.

K

[britinusa]

Thanks Ken. I'll check them out at the local AutoZone store.

[KWKloeber]

The last I bought them (10+ ago,) AutoZone didn't carry Dayco but Advance Auto and NAPA did.

[Ron Hill]

Paul : Gates (Rubber Co) is also a very good brand.  Gates also made belts for NAPA - don't know if they still do or not ? 
Just make sure that the belt is "ribbed" on the top(for cooling)

A thought