Kohler Generator Belt

[MORNING STAR]

I am breaking belts on my 1984 Kohler Generator (Perkins engine) like there is no tommorrow. 6.5 years without any trouble (broken belts) and now one breaks every 40 to 50 hours ( every 4-5 days of travel) or so which is a lot when you go cruising to Nova Scotia and back!!

Does anyone have any ideas of what the trouble would be?? A Kohler Distributor's tech that looked at it said it may be the type belt I am using which is a NAPA belt.


Dennis
Morning Star

 

[SKYCHENEY]

Does the belt track straight when running? A bent shaft or a worn sheave could contribute to it. Or, if the belt is being tightened to much.

 

[MORNING STAR]

According to the tech all looked fine. However, he did say he "really tightened it down so it should not get loose again". I have since learned as you said that this is a mistake!!

Thanks for the comment.

Dennis
Morning Star

 

[MikeP]

My last boat had a Kohler that went through belts very quickly. Turned out it was caused by a lot of rust on the pulleys that was essentially acting like sandpaper and ripping up the belts. This also left a lot of black dust in the vicinity so if your's isn't doing the black dust thing, the problem is most likely not rust on the pulleys.

In my case, I put some fine sandpaper on the end of a small wood block shaped to the taper of the pulleys. I ran the engine while CAREFULLY holding the block/paper into the taper of the bad pulleys. After about 20 minutes and several sheets of paper, the last being 400 wet/dry, the pulleys looked new and I never had any further problem.

Hopefully it's something this simple!

Belts that are too loose are also prone to break - the flapping creates quite a shock load. Install a new one, run it for an hour or two and check it again. A fairly standard check for belt tightness is to twist the belt. If you can twist it with your fingers more than 90 degrees, it is too loose. Another old standard is that the belt should deflect approx 1/2 inch when checked at its longest run between pulleys. Less than 1/2, it's too tight. Of course. all these old standards have no actual measurement of force involved. I might not push as hard against the belt as you do or I might not be strong enough to twist it as far. But these standards have been around for years and seem to work tolerably well.

 

[spartonboat1]

There are specs for the degree of flex that a belt should exhibit over a given span. This is expressed as so many fractions of an inch at a certain pounds of pressure at the center of the belt span. The old rule of thumb was about a 1/4" under moderate thumb pressure..should not need to be tight as the proverbial G string. You can actually buy a small gauge about the size of a large ballpoint pen for this. Then you need the specs for your size belt.

It may also be that the pulley groove has worn and the belt is now riding much lower in the pulley. Quick eyeball check is that the exterior belt surface should be about even with the pulley o.d. or slightly below, but not much.

P.s, could be bad belts...not unheard of for bad belts to get out, but rare. Might try the Goodyear Gaterback, which are heavier and notched for cooler running.

 

[Trojan]

You need to look at the belts real close and see how they break. Are they burnt,over streached ,to far down in the gruve,too much side ware or ripped apart. There are differant tapers and grades of belts. Where are you getting your belts? I would not use an automotive type belt. I would use a belt used on an industeral exhaust fan,a heavyduty. Maybe you need to purchase a belt from Kohler and see if they last longer. Bill

 

[spartonboat1]

Quick note re: tension gauges. The ballpoint pen size is a spring loaded gauge that indicates the load in pounds... There is a specific gauge for testing belts that are a pressure indicator and two fingers that grip the belt...

setting belts can actually be quite a precise process...

 

[captddis]

If this is the 20 kw gen. with the tensioner ,this is a common problem.
It is made worse if you are using the cogged belts. It seems to shred them when the tensioner pushes them in the opposite direction. I have solved this by eliminating the tensioner and getting a belt that fits tight without the tensioner. It takes a little trial and error but when you get it right ,you can get the five year life out of the belt . I can look for the belt # if you would like. Dave Ps I have six of these beasts in different boats I maintain and they all had this problem.

 

[MORNING STAR]

Guys,

Thanks to all of you for your thoughts and advice. I will take all the info and try to solve this problem.

To answer a few of the questions and comments I have listed some response below:

Yes Mike I do have the black dust--lots of it each time one lets go. I clean the front of the engine just to see if it comes back and it always does.

Sparton,I will check the pulley grove. I also heard that could be the problem.

Captddis, I think I have what you are describing. The "idler pulley" , which is used to put tension on the belt, is "flat" inside and actually puts tension in reverse of what you would expect. Instead of adjusting out as in most installations, this one moves "inside" or toward the center of the engine to put pressure on the belt. However, if this is the way it always was it went for 6.5 years without a problem.

Captddis,I would appreciate it if you could tell me the # and type and mfg of the belts you are using. That would help a lot.

Again, Thanks to all and if anyone has any additional thoughts please let me know.

Dennis
Morning Star

 

[MORNING STAR]

Captddis,

Did you ever get the #, size and mfg of the 20kw Kohler belt you are using?

I found rust on all the pulleys and have sanded them clean/smooth. I also was told to get a different size belt from Sam's which I got and have installed. Time will tell if these "fixes" fix the problem.

Dennis
Morning Star

 

[captddis]

Sorry I forgot . I will get it next trip to the boat. Dave

 

[captddis]

The belt I am using ia a Napa # 25-11933, size is 25/64 x 47 5/8. This fits tight and has been on for a few years without a problem. Just remove the idler and install belt. The pump will be a little tight to install but everything will settle in. Dave

 

[MORNING STAR]

Thanks very much !!!!!

Dennis