Deprecated: Function set_magic_quotes_runtime() is deprecated in /var/www/vhosts/tartan37.com/httpdocs/t37forum/common.php on line 88 Tartan37.com • View topic - Alternator Belt Tension

Tartan37.com

Tartan 37 Owner's Forum - Ride the wind, but look good doing it!
The time is 25 Oct 2020 13:59

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 7 Posts ] 
Author Message
 Post subject: Alternator Belt Tension
PostPosted: 30 Aug 2007 15:00 
Offline
Midshipman

Joined: 23 Dec 2006 17:26
Posts: 72
Hello Board,

Does anyone know how tight the alternator belt should be on the W50? Mine has a good ?? to 1? play in it and that seems too loose to me. The belt seems to vibrate quite a bit while the engine is on and I don?t want to damage any pulleys, etc.

Thanks in advance for your reply.

Mark


 
 Profile Email  
 
 Post subject: Re: Alternator Belt Tension
PostPosted: 30 Aug 2007 16:01 
Offline
Midshipman

Joined: 24 Oct 2006 16:10
Posts: 61
Mark,

I have always been told that the belt should be tight enough that you cannot pull on it and have it slide around the pulleys. Mine was loose enough that you could pull it around the pulley and there was powder debris that was on the engine from the belt. I tightened it up to the point where it would not slide anymore and it has run fine.

Craig Connolly
T37 #231
Recollections

_________________
Regards,
Craig Connolly
Recollections
T37 #231


 
 Profile Email  
 
 Post subject: Re: Alternator Belt Tension
PostPosted: 04 Sep 2007 06:58 
Offline
Midshipman

Joined: 30 Oct 2006 15:40
Posts: 63
I don't have a technical answer for you, but in my inexpert opinion the belt should be just tight enough so it doesn't slip. Slippage would be indicated by belt squeal when reving the engine, etc. We have a 100 amp alternator with a single belt. The high load of the alternator when charging requires a very tight belt. Of course the design location of the alternator agrivates this problem. The long, loose (undriven) span of the belt, from the drive pulley to the alternator, also agrivates the slippage. I have been toying with the possibility of adding an idler pulley on this segment of the pulley to dampen the motion and reduce slippage. But that's another issue. The bottom line is that if your belt doesn't slip it's probably tight enough. The system seems to be very hard on the belts and results in the continuous wear as evidenced by the black residue. This is even wourse with the 100 amp altenator. The belt should have been a cogged serpentine belt or at least a double belt drive. Last, don't forget to re-tighten the belt occasionally as they stretch with age.

JAMMIN' #226


 
 Profile Email  
 
 Post subject: Re: Alternator Belt Tension
PostPosted: 05 Sep 2007 20:18 
Offline
Able Bodied Seaman

Joined: 31 Oct 2006 19:43
Posts: 36
More on belt tension

http://www.westerbeke.com/Online_Manual ... at_man.pdf

Click on the link above and go to page
Page 46. It has a very easy to understand belt tension guide. I did find a technical engineering site from a belt manufacturer that provides an exact formula method of belt tension from many inputs such as pulley diameter, HP of load, number of belts, speed of belts, etc. I followed it through in my head and came up with roughly 1/2 inch deflection with a 28 pound force (thumb pressure) applied half way between the pulleys. I would use the Westerbeke drawing on page 46 of the link above and push with the thumb very firmly. I used my thumb to measure force on a scale and I was able to go over 30# but just barely, with my index finger I could not push down with more than 24#. I think the actual thumb pressure could be 20 to 30 pounds and still achieve proper tension, all I am saying is I think it is unlikely that you would be able to push too hard with a thumb. While looking around for this information, I notice that some belt manufacturers claim that recent developements in v-belts have increased the power transfer capability by 40% since 1980 when I presume the Westerbeke manual was written. Also note that in a properly engineered drive system, the belt, under proper tension, will "wedge" in the groove providing additional friction to power a load, but if the belt is not tensioned properly, centrifugal force of the spinning belt will lift the belt from the groove making the belt slip at high speed even if it appears tight when stopped.

Sam
Windfall #52


 
 Profile Email  
 
 Post subject: Re: Alternator Belt Tension
PostPosted: 06 Sep 2007 08:49 
Offline
Midshipman

Joined: 23 Dec 2006 17:26
Posts: 72
Hi Sam,

Thanks so much for that information! Great stuff.

Mark


 
 Profile Email  
 
 Post subject: Re: Alternator Belt Tension
PostPosted: 20 Feb 2008 11:19 
Offline
Able Bodied Seaman

Joined: 24 Oct 2006 12:51
Posts: 48
Looks like Sam has it right. One additional thought. More is not better. Excessive tension will certainly shorten the life of the freshwater pump bearings, a $300+ part.


 
 Profile Email  
 
 Post subject: Re: Alternator Belt Tension
PostPosted: 21 Feb 2008 13:56 
Offline
Skipper

Joined: 27 Oct 2006 10:32
Posts: 826
Has anyone considered adding a belt tensioner like you have on most cars these days?? I would think you could possibly add one without too much difficulty,


 
 Profile Email  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 7 Posts ] 

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 5 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Powered by phpBB © 2002, 2006 phpBB Group