Alternator belt adjustment

[NYCatalina30]

Good morning,

I've noticed my alternator belt has at least 1'' deflection when pushed (while 1/2'' is optimal). I seem to remember adjusting it as I did my end of season oil change...I've been racking my brain since last night and looking through the Universal 25XP manual as to how to make the proper adjustment. Even on line I'm failing to find images of the required bolts to loosen. I remember one being higher up and in plain sight, however is there a second one? A base mounting bolt that needs loosening too? Where is that found?

 

[Maine Sail]

It depends which alternator bracket you have on the engine. An image of the alternator would help. Some early XP's had an alterntor bracket that was prone to failure. This is a failure that can destroy the engines timing gear case, which is no longer avaiable. If you have the bad bracket, you will want to upgrade it ASAP.

 

[jssailem]

Pictures NYCatalina. They are so valuable to get assistance.

 

[weekendrken]

NYC- there was just a discussion about this (with pics) over on the ‘official’ Catalina 30 Assn forum. You might look over there or cross post your question?

 

[NYCatalina30]

I captured this from another post. My Universal 25XP looks the same (w/Oberdorfer). I see the one bolt mid-span behind the belt on top. Adjusting just this one is not sufficient though correct?

 

[Maine Sail]

You need to loosen the bolts at the alternator foot (the alternator is upside down on that engine, but the the 2" foot is the "foot"), adjuster ear on the alternator and the top bolt where the arm has the short slot. If your belt is worn, as it appears in that photo (sitting way low in the alternator pulley), you may not have any room left on the adjuster arms slot.

 

[d-marko]

How do you guys tension the belt? I've had quite the time trying to tension the belt to 1/2" deflection.

 

[LeslieTroyer]

This is my system for a M25. If you get the MainSheet it’s written up in there.

 

[Hello Below]

How do you guys tension the belt? I've had quite the time trying to tension the belt to 1/2" deflection.

This tool allows for easy adjustment of a belt. The bottle screw holds the tension while you tighten down on the alternator bolt(s). Make sure you remove it before starting your engine.
I have also used the Gates belt tension tester (Krikit) although I find the thumb deflection works just as well.

Belt Tension Jack

 

[Stu Jackson]

Alternator Belt Tensioning Tool Alternator Belt Tensioner FLIX

Just as important is alignment:

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

Universal M-25 & M25XP Alternator Bracket Upgrade & Alignment

 

[Stu Jackson]

You could follow Ken's advice, and you can go here:

Engines 101 - The BIGGEST & BEST collection of M25 Series Universal Engine Information on the Internet, plus some M35, too

Diesel Engine - c34.org

Different boats, same engine.

 

[weekendrken]

hey d-marko: you can buy a $$ tool - or as a C-34-er did you can make one for about $6.
As I said, there's a recent remove/change belt thread over on the IC30A forum -- see the link I posted about a cheap tensioning tool (in msg #105831.)

As well as the great info here there's also a wealth of info over there.

-k

 

[d-marko]

hey d-marko: you can buy a $$ tool - or as a C-34-er did you can make one for about $6.
As I said, there's a recent remove/change belt thread over on the IC30A forum -- see the link I posted about a cheap tensioning tool (in msg #105831.)

As well as the great info here there's also a wealth of info over there.

-k

Thanks all for the suggestions. Ken your link in that message looks like best route for me currently.

fyi for anyone else i have tried (C30 with m25xp):
1. Belt jack tool - worked really well but after a few uses broke at the weld as many others have experienced
2. trigger clamp - became to difficult to spread the pulleys once the belt got tight, not enough tension and the ears eventually slipped off
3. pry alternator away with long screwdriver - difficult to do on the m25xp with the upside down alternator. was able to insert screwdriver from underneath the alternator and pry it away. I got enough tension so the belt flap is minimal, but not quite enough to get to 1/2 deflection. it was more like 3/4" and it barely registered on the Kirkit

will try the turnbuckle idea next. Home depot has them and i'll try flattening the ends with a dremel

 

[weekendrken]

For what it’s worth when at Tractor Supply one day I looked at different ones to see which the best type eye bolt. I hadn’t yet bought one (was 700 mi from the boat that day.).
to improve a little on a great idea and ride against the pulley better my thought was if the eye was welded closed it could be cut and opened up into a fork. Or hammered from round to oval, flat, or maybe concave.

I figured it was worth the cost of a turnbuckle to try it.

 

[LeslieTroyer]

The one I use has hiem joints at each end to allow fo misalignment. About $10 on eBay. I welded up the alternator side bracket and shoulder bolt on engine side.