Careful Engine Inspection & M25 Alternator Pivot Bolts & Tension Nuts

[Stu Jackson]

Recently, Stewart Napoleon, Hull #1472, Desiree, posted his experiences with oil in his engine, here:  http://c34.org/bbs/index.php/topic,5073.0.html

I want to take this opportunity to say a great big THANK YOU to Stewart for his topic because it MADE me look EXTREMELY carefully at my engine and its parts.

What I found was a MAJOR crack in the casting of my alternator.  I discussed it with Harv at Blue Circle and just shipped it back to him today.  I'll keep you posted on what happens.  I'd been having trouble keeping my alternator belt tensioned, and with Stewarts' experience in mind, looked very, very carefully at everything.

The second picture is of the engine room, where a simple once over visually would most likely NOT have found this.  Believe me, I almost used a microscope!

Lesson Learned:  ONLY YOU can care enough about YOUR OWN engine to find these kinds of things.  There is no magic boat mechanic good enough to care enough about YOUR engine than YOU!!!  And there's no manual written about this...the alternator didn't even come with a wiring diagram!

[Ron Hill]

Stu : Good Point !!
Looking at your #2 picture (enlarged) of the engine compartment.  I don't see any washers/spacer (the same diameter as the alternator casting or larger) to take up the space between the bracket on the alternator and the aft bracket that holds it on the engine!!!  It almost looks like the bolt is bent. 
That space must be filled or you'll get compression on the engine bracket when you tighten that bolt.

At least you didn't meet your "Waterloo" like Stewart did.   A thought

[Stu Jackson]

Another good link re this topic is the Alternator Belt Tensioner FLIX topic (http://c34.org/bbs/index.php/topic,3667.0.html), where I just included this 2001 discussion on page 3:

http://c34.org/bbs/index.php/topic,255.0.html

I have my new alternator in hand, just got authorization from my doctor to put weight on left leg, so will install it soon and get back to sailing! 

AND 

[Stu Jackson]

The C34 Tech wiki on the alternator bracket repair has been updated (Oct. 2011) [http://www.c34.org/wiki/index.php?title=M-25_Alternator_Mount_Conversion_Kit_%22B/M_256891%22] to note that the bolts used should be metric, not SAE.  

I attribute the failure of my alternator casing to the wrong bolts.  

I was able to procure metric bolts at a local hardware store.

I recommend you check your alternator if you've updated the bracket on your M25 engine.  If you have the smaller (thinner) SAE bolts, they'll allow your alternator to wobble.  A LOT.  It contributes to belt wear even if you think you've lined up the pulleys, and lets the alternator droop and lose belt tension.

I've added a link to the wiki to the C36 Forum that shows pictures of the different bolt sizes.

I also included the full text of the wiki about the metric bolts here:  http://c34.org/bbs/index.php/topic,7005.0.html

It says:  

October 2011 - From E. Herlihy an O'Day 35 owner: Last November (2010) I installed the upgraded Alternator mounting bracket, with the kit available through Torrensen Marine, and while I was at it I installed a new Leece-Nevile / Prestolite 90 amp alternator on my Universal M25. If you are reading this far, you probably know that the new alternator uses EXACTLY the same housing as the old 55 amp Motorola. BTW the kit is now ~$180.00 When I opened the box containing the kit, I was happy to see that it included all the parts, including the Alternator mounting bolts. I did the installation using the new bolts, but noticed that they did not seem to fit perfectly. The SAE Grade 5 pivot bolt allowed "a little" play of the alternator, and the tension bolt never seemed to fit "right." At the time I assumed that the alternator was machined so that the bolt would jam, thus preventing the bolt from loosening. The real reason is embarrassing....

I thought it strange that both of these bolts, and the nut were SAE. 031555 - 5/16NC x 1 031615 - 3/8NC x 3-1/2 031762 - Nut 3/8-16 Hex Steel Zinc

However, EVERY other fastener is Metric. I assumed that Torrensen would know and include the correct bolts, however the extra play was because the bolts did not fit... you know what happens when you ass-u-me... The Pivot bolt SHOULD BE a Metric M10 fastener. The tension bolt (connects the tension arm and the alternator) SHOULD BE a Metric M8 coarse thread. I realized this because I was getting a little belt dust on the engine. After only 50 hours this summer, I thought that was unusual, or I would need to buy a lot of belts. In October of this year (2011), I checked the alternator tension, and the "little" play seemed a "little" worse than it should have...

Because by now I had stripped some of the threads with the bolt that was included with the kit, I purchased a slightly longer bolt, a nut, and lock washer to use as a tension bolt. I also replaced the pivot bolt with a slightly longer M10 Fine thread bolt. It fit perfectly (no play at all). I used 2 nuts and a spring washer to jam the pivot bolt, so that it will not vibrate loose. I can't speak to the kit available through Catalina Direct, but the Torrensen kit has the wrong bolts!

Lesson 1: If the components in the "kit" don't seem right to you, they are not. Lesson 2: DO NOT USE THE ALTERNATOR MOUNTING BOLTS INCLUDED IN THE TORRENSEN KIT if they are SAE, and you have a Leece-Neville or Motorola Alternator.

[Ron Hill]

Guys : While Stu is on that topic, I wrote a "Tip" long ago that needs to be repeated. 

On the M25XP and the M25 with the alternator modification (adjusting arm under rather than over the alternator) the two bolts that hold that arm are short bolts.  The holes that these bolts screw into are threaded all the way through.  So why not get a longer bolt (by about 1/2") and have more threads holding the alternator and arm in place!!   A thought

[Les Luzar]

I have never really looked that close at my alternator bracket. I am going to inspect it closely this weekend to see if I have a spacer or not! Just for fun!

[mainesail]

Guts don't feel bad the Universal engines are not the only ones that have improperly sized pivot bolts. MANY factory engines including Yanmar, Volvo/Perkins and Universal often ship with the wrong sized bolt for the alternator to pivot on. With a 35A alt this is rarely a problem but when you go to 80A+ it quickly becomes belt dust bonanza.. Universal also shipped a number of engines where the Motorola alts had SAE holes and yet others with metric, go figure. The alt bracket upgrade, IMHO, is a rube Goldberg fix and rather poorly engineered, but still far better than the original.

Please be aware that the long alternator 3/8" bolt that comes with the kit is most often the WRONG size. It is much to sloppy a fit in the bracket. The hole in the bracket works MUCH better with a metric bolt. I replace it with a metric bolt and occasionally need to then drill the alt to the proper fit. The problem is the Motorola alts shipped in both metric and US sizes over the years. The upgrade bracket is drilled for metric but Westerbeke ships a 3/8" bolt.. Belt issues with the new bracket are often due to the sloppy incorrect bolt Westerbeke supplies. It allows the alternator to "cock off" and create uneven belt wear and creates wear on the alternator foot mount.

Also the new bracket has oval holes for a reason, but every one I have seen installed has never taken advantage of them. You may not need to but you really should align the bracket fore/aft on the motor so the belt is in proper alignment.. This may mean spacer washers under the thermostat end of the mount. The one I just did required two metric washers to shim it forward..

Sloppy Fitting Westerbeke Bolt


A much better fit:


New bolt on left, Westerbeke supplied "sloppy" bolt on right:


Forward Align


If you forward align place shim washers in the space:


Aft Align:



To Ron's point about the adjusting arm bolts, which is a good one, I go one step further.

I get a real long bolt, split washer and nyloc nut. I then adjust the arm and tighten the bolts hard. Once tight I install the "locking" nuts. I've yet to have one vibrate loose after this fix..

Alternator Ear End (gets both split washer and nylock nut. If the alt over heats it could melt the nyloc feature.)

Slotted end of adjusting arm: (this should never get hot enough to melt the nyloc if it does you have bigger issues.)

[Stu Jackson]

New bolt installed today.

What a difference!

Pictures:

Crack in SECOND alternator.  Alternators should last longer than this one (2004 to 2009) when the first crack appeared, and from (2009 to 2012) BUT I was NOT sailing for most of 2009 and 2010 'cuz of my broken leg).

The small 3/8" inch bolt is, as Maine Sail notes, totally INADEQUATE to support the WOBBLE of the alternator.  The M10, 100 mm, bolt is very noticeably stronger.

Please check your bolts if you have an M25 engine with the alternator bracket upgrade kit.

Please also check if you have an M25XP.  Wouldn't hurt, eh?

This picture shows the start of the same kinda crack as pictured above with the previous alternator.

[Stu Jackson]

Alternator belt sources

NAPA is a GATES belt.  Read the back of the packaging.

for 'no worries': I've changed the subject of this topic at least three times, to make it more meaningful.

[Ron Hill]

Guys : Stu is correct about Gates making the NAPA belts, BUT:

The NAPA dealer wanted $15 + while the auto store that stocked Gates wanted $8 + !!!

Your choice!!  

Also that bolt holding the alternator should NOT be stainless (for extra the strength).

A few thoughts

[Stu Jackson]

Put the new alternator on yesterday.  The new pivot bolt was in.  The top bolt was a 5/16" by 1 1/4", didn't have enough length in the back to add the nylock.  The longer 5/16" bolts (1 1/2") did not have threads along the entire length and wouldn't work, so used Ron's "longer bolt" method.  A regular nut may work, we'll see.  The bottom alternator bolt was an M8 long enough to install a lock nut and nylock.

The belt stays tensioned now.

[Stu Jackson]

The belt stays tensioned now.

NOT!!!  Drats.  More investigation tomorrow.  I couldn't get a nylock on the adjusting bolt, too deep, will try a regular nut with a lock washer.

[Ken Juul]

Stu it may be that the new belt has stretched.  I'd re tighten and try again before re-engineering.

[Stu Jackson]

Ken, thanks, the belt had been lightly used, but I will do so.  No re=engineering, just implementing Maine Sail's suggestions on the "nut & bolts." 

[Stu Jackson]

The 1 1/4" lag bolt didn't work because the shank didn't have threads all the way.  The 1" lag bolt was too short.  So I bought a 1 1/2" screw, put a washer on the front and a lock nut and regular nut on the back.  So far, so good.

This is the 1 1/14" lag with the 1 inch lag.