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Old 22-05-2019, 14:08   #16
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Re: Perkins 4.236 v-belt/alternator issues

I also have a 4236 and single pulley alternator drive belt using the original bracket. When you get your alternator pulley replaced try the NAPA 25-9520 belt which is what I use. Driving a 120 amp alternator, these belts last about a season. Admittedly the adjustment is about maxed out with this bracket but the next size shorter belt is too short. Good luck.
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Old 23-05-2019, 08:40   #17
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Re: Perkins 4.236 v-belt/alternator issues

Many thanks to everyone for their help. I have learned a lot throughout the course of this discussion, and I think I am finally getting to the bottom of it.

Mo, it's funny that you mentioned the Napa 9520 belt. I think the root of the problem was a worn-out 9520 belt. Before now, I had never taken the belt off, because it looked like new from the outside (probably because it was mis-aligned and shaving itself down to fresh rubber constantly).

See photo (note the teeth are completely missing from one section. Belt is also significantly skinnier than the fresh 9520 I replaced it with):
https://photos.app.goo.gl/zNs5rAWAUT7ZYkVDA

My best guess at what happened is this: previous owners were having belt issues, and the old 9520 was worn and stretched to the point that the original bracket couldn't hold it tight enough to recharge the batteries. So instead of replacing the belt, they added another bracket to force it tight. But the addition of the bracket caused mis-alignment and chewed up the belt to the point that it wasn't making proper contact with the alternator pulley, and with all of the 'pivot points' and poor leverage you have with two brackets, it would never stay taut for long, and it finally got to the point where it just didn't work.

I have removed the aftermarket bracket, and am now just using the original bracket and a new Napa 9520 belt (only because there were extras on the boat, and it saved me a trip to the auto parts store). Mo is right, the 9520 is a little on the long side and nearly maxes out the original bracket, but even with just a moderate amount of tension, I was able to produce 50+ amps yesterday without any squeaking or slipping. For now, I'm claiming victory. Thanks again for everyone's help. Now I can continue north to Beaufort SC with confidence.

-Arthur
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Old 23-05-2019, 09:15   #18
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Re: Perkins 4.236 v-belt/alternator issues

POS - Prior Owners (um...) Stuff

Takes a while to clean up POS.

Do take a moment to go get any of the top rated belts of the right size for your application.
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Old 28-05-2019, 19:29   #19
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Re: Perkins 4.236 v-belt/alternator issues

Short story...
My 4-236 has a 120A alternator hanging off it. When I purchased the boat it came with 8 spare belts.... seems excessive. After much fighting and measuring and aligning, it still managed to eat belts due to the high load.
I wholeheartedly recommend the serpentine kit. No belt dust, no squealing and slipping.
I was really put off by TAD's price and hunted around. In the end I purchased just the water pump pulley and the crank pulley $484 from them. A local alternator shop supplied the alternator pulley ($10 installed, used.)
I had to fab a new alternator bracket to keep the alignment right but theirs would not have worked for me anyways as my alternator faces the engine due to space constraints.
It was a lot of cash for what it is but, to me.... it has been worth every penny.
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Old 02-07-2019, 05:16   #20
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Re: Perkins 4.236 v-belt/alternator issues

Just an off-question if you donít mind. Do you find the Perkins a bit small for your 42 footer? My 26 footer used to have a Perkins 4236T. Ripper engine.
Regards,
Mick
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Old 02-07-2019, 08:11   #21
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Re: Perkins 4.236 v-belt/alternator issues

Quote:
Originally Posted by Shanty1 View Post
Just an off-question if you donít mind. Do you find the Perkins a bit small for your 42 footer? My 26 footer used to have a Perkins 4236T. Ripper engine.
Regards,
Mick
4-236 is 75-85hp, lord only knows how many ft-lbs of torque (300-350ft/lbs).... more than enough for a fat full keeled 43 footer, at 37500 lbs. The 4-236 is a popular engine in larger 70's and 80's sailboats. Unless it was a tug, I cannot imagine a 26 foot boat needing a 4-236, a 4-99 , 4-107 or 4-108 maybe.
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