Securing the Alternator on our M25-XP

Securing the Alternator on our M25-XP Engine

The alternator on our Diesel Engine has moved about due to vibration (hey, it's a 3 pot Diesel) and has broken the support arm twice.

I purchased a new 10mm x 100 mm bolt and a Nylock nut to replace the old one just in case some of the slack in the Alternator mounting was due to a worn bolt.

It also occurred to me that the mounting bracket spacer might not be suitable for the Alternator ( which we replaced a few years ago). My calipers were not accurate enough to measure the gap between the Spacer and the Alternator Ear (I think that's what they call it), it would really require a Micrometer and I don't have one ( YET! ) 

On Amazon I found some 10mm internal diameter shims, 10 each of 0.1mm, 0.2mm, 0.3mm and 0.5mm and purchased those.

By trial and error process, I figured that the existing spacer between the Alternator support brackets and the Alternator Ear had a 1.2mm gap.

Using two 0.5mm shims and one 0.2mm shim the alternator 

With those 3 shims in place, I was amazed at how batter the alternator was supported by the brackets.

It took about 10 minutes to fiddle the shims on to bolt after it passed through the foremost support bracket, then get the Spacer onto the bolt, there is obviously almost no gap now, and finally the bolt into the aftmost support bracket. With the Nylock in place but barely tight, the alternator felt rock solid in the mounting.  

After adjusting the drive belt tension and securing all 3 of the bolts that hold the alternator in place, it feels total as one with the engine. Solid! 

With everything tightened up, Peggy started the engine. Not a hint of a squeal when she shifted the rpm up to cruising speed and no movement of the alternator. 

I'm hoping we have cured that issue of vibrating alternator and subsequent breakage of the tension support arm.

I hear the waves beating against the bow! See you on the Water.