Belt tensioner

[sail4dale]

Been amused at all the conversation about belt tensioning ..... I really didn't think that much about the problem and several years ago
I noticed the excessive flop of the belt.  So I merely loosened the nuts on the alternator and by pressing down with one hand I tightened
the nuts and .... success   Several outings later after my haul-out we left the yard for home and noticed SMOKE! Lots of it coming our of the cabin.  ... steps off,  doors open and ..... CRAP!!!!

I my fervor in tightening I overlooked the possibility of TOO TIGHT.   What happened it the over tight belt put a side load on the salt water pump
which froze up, burning up the belt, twisting the pump off the holding bolts and shearing the inlet and outlet hoses.

Fortunately we had not got too far from the boat yard so got back and purchased a pump, hoses, and labor to install.

Valuable lesson for me.   A little loose is batter that too tight.  I would think that the tensioner mentioned might lead
to some over tightening if one was not vary careful. 

[Set2sea]

I use the aforementioned  tightener, have followed all tips for hardware - M10 instead of 3/8 bolt, I get the belt nice and tight and it doesn't stay tight. I do have the bracket upgrade.
Anybody else seeing this?

[Mike and Joanne Stimmler]

Your belt might be stretching. Is it a good quality Gates belt?

Mike

[Ron Hill]

Paul : I mentioned this "tip" many times. 
If you look at the bolts on your tension arm you'll find that the female is threaded all the way thru.  Get yourself a bolt that is about 1/4 - 3/16" longer and you'll have more threads to hold.  That will probably solve your "loosening" problem.

A thought

[Set2sea]

Paul : I mentioned this "tip" many times. 
If you look at the bolts on your tension arm you'll find that the female is threaded all the way thru.  Get yourself a bolt that is about 1/4 - 3/16" longer and you'll have more threads to hold.  That will probably solve your "loosening" problem.

Ron, I have done that. I even went longer and have a locking nut on the back side.

A thought

[KWKloeber]

Five things:

What belt make and number are you running.

Do you notice belt dust around the pulleys? 

Have you marked the alt frame position on the arm - ie, is the adjustment actually slipping?

Have you aligned the alt with the crank and closed coolant pump so the belt is running true and square?

What width is the alt pulley and is it  stamped or machined?
(maybe that makes 6).

kk

[Set2sea]

Five things:

What belt make and number are you running.

Do you notice belt dust around the pulleys? 

Have you marked the alt frame position on the arm - ie, is the adjustment actually slipping?

Have you aligned the alt with the crank and closed coolant pump so the belt is running true and square?

What width is the alt pulley and is it  stamped or machined?
(maybe that makes 6).

kk

Thanks for the list of things to check. I will have to get to the boat to answer some of them.
I have been seeing belt dust. I was attributing that to running with a loose belt.
I will put a mark somewhere to check. The alignment looks good, I put a right angle square to check. I don't know what you mean by "closing the coolant pump"?
What is the deal with stamped vs.machined alt pulleys? I will have to check that and belt size this weekend, I know it is a Napa.
Thanks for the help
Paul

[KWKloeber]

Paul,

Yep, those things are key to drilling down to the cause.

RC had a pretty good discussion re: specifically the pulley and alignment issues - I don't recall if it was on his mainesail DIY website or on a SBO website post.  Sometimes one posting is more complete or up to date on a topic  than at the other location. A mismatch due to wrong width is possible.  Sorry, I don't have links to it-maybe Stu or Ron?
Note that my: "closed coolant" pump (was vs "sea water coolant" pump.)

The best belt is a
Dayco Top Cog brand  heavy duty with the top serrations - JTSO, others' mileage may vary. It's what my Wb supplier recommended several years ago and it eliminated any slippage issue for me, and is the only one I'll sell or recommend to customers.

Anything other than checking those causes and still slipping may be due to voodo or karma!

Ken

[Stu Jackson]

I use the aforementioned  tightener, have followed all tips for hardware - M10 instead of 3/8 bolt, I get the belt nice and tight and it doesn't stay tight. I do have the bracket upgrade.
Anybody else seeing this?

Yes, happens to me all the time.

In answer to Ken's question about links, it's in the "101 Topics", here:

Universal M-25 & M25XP Alternator Bracket Upgrade & Alignment 101 IMPORTANT

http://c34.org/bbs/index.php/topic,7917.0.html

There's also a link in the Tech wiki, under Engines, IIRC.

[Set2sea]

I use the aforementioned  tightener, have followed all tips for hardware - M10 instead of 3/8 bolt, I get the belt nice and tight and it doesn't stay tight. I do have the bracket upgrade.
Anybody else seeing this?

Yes, happens to me all the time.

In answer to Ken's question about links, it's in the "101 Topics", here:

Universal M-25 & M25XP Alternator Bracket Upgrade & Alignment 101 IMPORTANT

http://c34.org/bbs/index.php/topic,7917.0.html

There's also a link in the Tech wiki, under Engines, IIRC.

So Stu, you have to re-tighten your belt every so often?

[KWKloeber]

Paul,

Here's a link re: the Top Cog belt- read this post and the other follow ups. 
http://c34.org/bbs/index.php/topic,8063.msg56701.html#msg56701

I recommend this belt
http://www.daycoproducts.com/dayco%C2%AE-gold-label%C2%AE-top-cog%C2%AE-belt-with-laminated-construction

RC prefers this one
http://www.daycoproducts.com/dayco%C2%AE-gold-label%C2%AE-top-cog%C2%AE-belt-with-bottom-cog-construction

I don't have the knowledge base that RC does, but my understanding is that a "solid bottom" belt against the pulleys creates less heat, than does a belt with bottom cogs (seems contrary but that's what Dayco claims anyway -- maybe less slippage and better heat transfer is my guess??)  That contrasts with what RC says about the bottom cog style running cooler, but again he has infinite experience w/ belts.   I have not heard of anyone who was disappointed using either of the Gold belts.

Cheers,
Ken K

[Roland Gendreau]

Belt dust could be an indication that the pulleys are out of alignment, which causes accelerated belt wear.  You can use a metal straight edge laid across the crankcase pulley to check if the alternator pulley aligns with the crank pulley. 

I was able to correct this on mine by shimming the alternator bracket where it attaches to the engine.