Yanmar 2gm20F alternator prevents belt installation

[Brinky63]

I tried installing a Yanmar 2GM20F alternator belt on my engine but ran into an issue. The alternator has a small screw on the bottom that hits the oil filter preventing it from going down enough to place the belt on.

Belt code is YM-25132-003700, came in service kit MK-2GM20F from diesel parts direct, same code as a spare belt i have.

Alternator was service a while back after replacing the belt, suspect they might have added this to it somehow since i never had an issue before with the installation of the belt.

I purchased a car belt one size up but that fits just right in the meantime, will not be able to adjust it anymore.

Anyone else experience this issue before?

What does one recommend to replace the alternator which does not have this impediment?

 

[Tally Ho]

suspect they might have added this to it somehow since i never had an issue before with the installation of the belt.

It sure doesn’t look “new”, but there is a lot of belt dust all over, so hard to tell.

How much play in the alternator from fully tight to fully loose and resting on the oil filter?

Why not remove the oil filter? Maybe a good time to tackle that job too.

Greg

 

[dlochner]

As Greg notes, there is a lot of belt dust, could be an alignment or tension issue. Are you certain the oil filter is the correct filter? A shorter filter would would work.

The wires appear to be several ground wires, could they be relocated?

 

[Ralph Johnstone]

The alternator has a small screw on the bottom that hits the oil filter preventing it from going down enough to place the belt on.

Something not quite right there :

Am I correct in saying that your alt. is now located at the extreme portside of the curved adjustment arm ?

​

Looking at the underside of my alt, I see no protrusion as you have:

Please supply a wild guess as to how old your engine is. Also, please supply several pictures around the alternator at a slightly greater distance. I have trouble seeing how the alt. is mounted. A video around the alt. would be best.

Any guesses as to what that protrusion is on your alt ?

Please supply a photo of the ID plate on your engine :

 

[Brinky63]

Hi All,

Thanks for the feedback. Some info:

Boat is a Hunter 306 build of 2003, Yanmar 2GM20F build of 2003.

Lots of belt dust from the last belt, have not had time to clean up the engine. Wish my engine looked as nice as Ralphs!

Yes the alternator adjustment bolt is as far as it can go (to your white mark), which means that i cannot adjust it any further should it be required.

The oil filter is a Yanmar spec and comes with the maintenance kit. Removing it allows to place the original belt but then the alternator is in the way of installing the Oil Filter.

Not sure what the protrusion is, it's an electrical connection, might be the cable going to the panel in the cockpit . I’ll send some better photos and possibly a video for clarity.

Planning to remove the alternator all together to see if I can move it in another direction.

Any recommendations as to a replacement unit?

 

[Ralph Johnstone]

Thanks for all YOUR info @Brinky63 . Problems like this drive me vicariously nuts.

First off, you have exactly the same engine as mine (which is a 1997) as opposed to your approx. 2002 vintage. So what the hell gives ?

Planning to remove the alternator all together

An excellent move but handle it with kidd gloves as you remove it as you will "likely" be using it again for many years to come ............... UNLESS on the off chance the people who last serviced the alt. either added something (as you've suggested) or installed another alt. altogether.

Alternator was service a while back after replacing the belt,

Once you have the alt. out, could you please go over it with a fine tooth comb to see if you can find the ID sticker for the model number ? It should be :

HITACHI ALTERNATOR, LR155-20B 129772-7720, 12VOLT - 55AMP.

This was the original alt. which was installed in your Yanmar 2GM20F engine and worked well before "something" altered it. That small electrical piece you show looks to be so clean and tidy in its mounting set up, that it looks like an OEM component rather than an "add on" by someone at a later date. Crazy !

I've looked at few ads for this alt. and cannot see any protrusions like you have :

Alternator for Yanmar Marine 129772-77200, 12977277200, LR155-20B AHI0068

miltonautoelectric.ca

........................ unless something's changed over the last 20 years. Got to wonder if the body of the alt. can be rotated when it is re-assembled ? ? ? ?

Lots of pictures, closeups, videos, charcoal sketches, and whatever of the unusual device and the alt. casing please. I've never seen anyone complain about too many pictures being sent on a problem like this.