Changing Alternator Belt - Perkins M30

[Mike Smith]

I was cleaning up from the weekend cruise and doing some routine maintenance on Breezer today.  When I got to the engine I noticed about 1/2 of the outer layer of the alternator belt lying beneath it. Must have been that brief "whiff of burnt paper" smell Jan commented about as we left our favorite anchorage this weekend. I've never changed the alternator belt since I repowered with a Perkins M30, but I've changed belts before, so I got out the spare belt, my largest screwdriver, and a hex ratchet set.  Then I looked at the alternator and the bracket, ready to do battle. I started to loosen the bracket bolt and saw that the @#$%!! bolt was in backwards! And there is very, very little room on the backside for any kind of wrench. I decided to think about this for a while and, in the meantime, a more pressing issue with the bilge pump arose, which has postponed the alternator belt impasse 'til Friday afternoon.

So, my question is, has anyone had any experience changing alternator belts on a Perkins M30, and how do you loosen/tighten the bracket bolt when applying tension to the belt? See three pictures below:
 
 
 

 
Mike and Jan Smith
S/V Breezer
www.mikejansmith.com

[This message was edited by Mike & Jan Smith "Breezer"  '88 #688 on October 13, 2003 at 10:33 PM.]

[This message was edited by Mike & Jan Smith "Breezer"  '88 #688 on October 13, 2003 at 10:35 PM.]

[Ken Juul]

Hard to see if there is room from the pictures.  Is it possible to get to the bolt with a socket and extension from behind the Alternator?  The other alternative is to disconnect the coolant hose to give you access to the bolt head.

[Mike and Theresa Vaccaro]

Mike,

Might want to post the the diesel engine forum maintained at the Torressen Marine site.  Can't provide a hot-link since I'm not that computer-savy, but a Google should do the trick.  Lots of good expertise available and the answer may already be in the archives.

Cheers,

Mike

[Ray & Sandy Erps]

Mike,
Wow, what a pretty motor and bilge.  I thought all marine motors were colored rust and black.  That's definitely a job for a 3/8 drive flex head ratchet with an eight inch extension working from the head through the little door to the engine compartment.  Engine manuals say to always disconnect the ground first.  I usually ignore that unless I'm around the alternator or starter.  Those two accesories can make for some big sparks and I hate buring the chrome off my shining tools.
Ray

[Stu Jackson]

Belt Tensioning

Mike

A reference for belt tensioning is:

http://c34.org/projects/projects-alt-bracket.html

Read further down the post, since the main story is about changing the bracket on a Universal.

Could be you're one of the only C34s without a Universal engine.

Good luck with the bolt.

Stu

[Mike Smith]

Thanks Stu -

As always, I did a search first and I recognized the post about the bracket failure as I read it. I'll pick up a belt tensioner on the way home this afternoon - at least that will free up my hands when I re-tighten the bolt.  The solution is to get the bracket in front of the alternator body so the bolt head is readily accessible from the front.  To me, this is just as much of a safety issue as changing the impeller - both need to be done quickly and with the bolt head behind the bracket that just isn't possible.  I'm checking with Perkins on other bracket arrangements - I may end up having one made. I recall reading somewhere about an emergency alternator belt - one that doesn't require full tension and can be used for a short time. I think it snaps together somehow. I thought Catalina used Perkins on some late model 34s, but I could be mistaken.

Mike and Jan Smith
S/V Breezer
www.mikejansmith.com

[Stu Jackson]

Mike

The emergency alternator belts are sold by West Marine.  I think they're organge in color.  Unless you have a problem with belt alignment, it would seem wiser and safer to just regularly change your belt.  (Easier said than done, it seems - me, too :))

Stu

[Roc]

I believe Catalina put Perkins engines in early C320's.  You may want to check that website.

Roc-

[Gene Regan]

Mike,

   Looks like remove th hose and work it from behing and above with open end or a ratchit box wrench, somthing of a thin shanked wrench would probably do ya.
   Have a set here at home by snap on
Gene

gene regan

[jentine]

Mike, It appears that you can remove the entire bracket, shim it out and replace it on the outside of the alternator ear.  That put the bolt on the accessible side for future use.
Jim Kane

[John Gardner]

Not from experience, but from your photos, I was going to suggest the same as Jim.  It looks to me as though one of the bracket attachment "bolts" is in fact a stud, so taking the bracket off might be awkward.  You might need to also take out the pivot bolt from the bottom, if you can get at it.  It might be easier in the end to remove the hose.  The only other suggestion is to check whether a really long extension, (or two), with or without the flexible extension mentioned above could do it.
However you achieve the objective, I would be inclined not to shim out the bracket, but to drill out the threads on the alternator.  Then install a nut and bolt - I assume you could get a wrench on the nut on the back side of the nut and bolt, and turn the bolt from the front.
Good luck.

[Mike Smith]

The Instant Fan Belt Tightener mentioned in the following is available from J. C. Whitney part #15ZX6161X for $9.99.


"Subj: [C34] Alternator Bracket M25 Engines
As far as belt tensioning - in the dark ages they use a mallet or pry bar. If you go to an auto parts store you can buy a "belt tensioning" tool. It's like a turnbuckle with a left & right thread at a whooping cost of $6-$8! Screw it out till you get the correct tension then tighten the alternator retaining nuts. Easy as pie. Then screw the tool off. Meant to put this in the Mainsheet as a tip. Don't overtension or you'll be buying a new internal water pump."
Ron, APACHE #788 ronphylhill@erols.com"

Here is the link to Ron's complete project:

http://c34.org/projects/projects-alt-bracket.html

Mike and Jan Smith
S/V Breezer
www.mikejansmith.com

[This message was edited by Mike & Jan Smith "Breezer"  '88 #688 on October 15, 2003 at 03:37 PM.]

[jentine]

You should be able to simply push the alternator to a taught position without the addition of mechanical means.  The additional tension puts an excessive strain on the alternator and waterpump bearing and results in premature failure.  I have never used a mechanical device including a pry bar to tighten the belt on any engine.
Contrary to common belief, the belt is supposed to have some give and deflection.  Application of a pry bar or other mechanical device will eliminate all play, causing stretching and pre-mature wear of the belt.
Jim Kane

[Mike Smith]

Well, I changed out the alternator belt today, and it wasn't as big a pain as I thought it would be. The trick is having and using the right tools. To get into that tight space behind the alternator bracket, I picked up a 12mm GearWrench ratcheting combination wrench at Lowe's. It has a crescent wrench at one end and a ratcheting box wrench at the other end which fits over the bolt head. The ratchet engages with only a 5 degree movement of the handle, which was more than adequate to easily loosen and then tighten the bolt. I just slipped it in on the right side over the alternator and loosened the bolt in a second. However the belt itself was a real bear to get on. Even with the alternator all the way to the left in the bracket, I still had to pry it onto the flywheel pulley with a large screwdriver. At first I thought they had given me the wrong size belt (too small). I used a mallet handle (my new belt tightener won't be here for several days) to pry the alternator to the right in the bracket, but only out about an inch to get the proper tension (1/2" deflection between pulleys). I ran the engine for 15 minutes and checked the belt tension again, and it was still deflecting about 1/2" so I figure the tension is OK. It seems to me that the belt should go on easily by hand and that the alternator bolt should be positioned out further toward the center of the bracket for proper tension. What do you think?

Mike and Jan Smith
S/V Breezer
www.mikejansmith.com

[This message was edited by Mike & Jan Smith "Breezer"  '88 #688 on October 16, 2003 at 03:38 PM.]

[Stu Jackson]

Mike

Based on the pictures, there just isn't room to get the alternator moved enough inboard to slip the belt on more easily.  There doesn't appear to be room enough to gouge more of a slit in the adjustment bracket.  The only other way I would see to do it would be to drop the alternator itself by removing the top bolt and the bottom ones, and reinstalling it every time.  

Anothr thought:  if you have the room to the port side, get a longer belt.  That way the alternator would be further to port, giving you more room to get the longer belt on, since there's still a lot of room on the top bracket for adjustment.

At least you got it on.  Maybe there's a Perkins owners website?

Good luck,

Stu