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jimbim · 29-04-2010, 01:22

I am in Salomague Harbor, an isolated little bay near the top of Luzon, in the Philippines. Hope to leave in two days for Ishigaki Island, Japan.

V-belt on my relatively new Yanmar 3YM20 has died a powdery death. This is what I did... In Bolinao, coming up here, it was squealing on start up, so I tightened it. That seems to have fried it, but I'm not sure.

The manual says the middle of the v-belt when tensioned should deflect 8-10mm (3/8") when pushing on the belt with a finger. How hard do you push? A belt would have to be pretty damn tight not to deflect 3/8" even when not pressing that hard.

I have one spare belt and am a little concerned I won't get this right. Any ideas would be greatly appreciated.

Jim

MarkJ · 29-04-2010, 02:02

Hi Jim,

I'll get pounced on for saying this by those that know, but I have mine far less tight than that.

ONe Yanmar guy said you twist the longest length and should be able to twist it 90 degrees. Then he realised that couldnt work as it would be too tight.

Just make sure it doesnt squeek.

or vibrate.

Mark

forsailbyowner · 29-04-2010, 02:04

You have it right. It should be very hard to push past 3/8" with one finger. When you tightened belt it was probably because belt was failing. I had same thing happen when I had to tighten a belt on two consecutive startups that then failed. Next belt has been 100 hrs with no tightening needed.

**GordMay** · 29-04-2010, 02:37

You should be able to deflect the v-belt about 1/4" to ½" for each foot of distance between pulley centres.

See ➥ Belt & Pulley - Cruisers & Sailing Photo Gallery

And ➥ Belt & Pulley - Cruisers & Sailing Photo Gallery

motion30 · 29-04-2010, 11:09

Has anybody tried the napa green belts? I had a gatorback over heat and snap as well

**GordMay** · 29-04-2010, 11:56

I believe that NAPA stores carry the Gates Green Stripe belts under private label of NAPA Gold Stripe.
➥ http://www.napabeltshose.com/downloa...IDE_FORWEB.pdf

motion30 · 29-04-2010, 11:58

Thanks Gord
These are the belts with the back of the belt all green not just a stripe They are gates hd

ViribusUnitis · 29-04-2010, 12:42

Your over thinking it. V-belt tension isn't that sensitive. If you have to keep adjusting the tension, the belt is streaching. If it's streaching, the fabric core is dammaged, and the belt isn't any good. Just go ahead and replace it when you start having to tighten the belt all the time.

If you find yourself with a busted v-belt, in the middle of nowhere, use a peice of light nylon line. Wrap it around each pully, and then tie it as tight as you can with a square knot, trying to have the knot fall on the outside of the pully as you do. Be sure to cut off all the excess line, and have a rather good knot.

Is it right? No, but you'd be amazed how long a light bit of nylon will run like this. Panty hose works really well too, so just raid your wifes stash.

jimbim · 11-05-2010, 23:47

Thanks to all who responded. Decided not to swap the worn belt for the new, instead get as many miles as I could from the old, snugged up a bit -- got us to Ishigaki, and about 30 hours of it under engine, so reckon we will see if it will get us to Okinawa where I will buy a few more belts, since my wife unfortunately has no panty hose aboard.
Jim