Electromaax Serpentine for M-25

[dparilla]

Well, we took the next step forward and ordered the serpentine belt kit for the Universal M-25 from Electromaax. Wouldn't you know it...it did not directly fit our crankshaft pulley (ours is not tapped to bolt the new pulley on it). So after discussing options with EM, I sent them my crank pulley and they are going to mold/mill a replacement pulley. Once I get it back and installed, I will post the results.

John at EM said they will set up a mold to make additional ones as people need it, so if you are contemplating the upgrade, give them a call. I have attached a picture or our crank pulley and the original "replacement" pulley.

Lastly, if you do go to remove the pulley, the retaining nut requires a 29MM axle socket. My dewalt rechargable impact wrench made quick work of removing the nut without damaging the shaft, or my knuckles.

 

[Stu Jackson]

Dan, when Maine Sail came up with this idea and/or Electromax did and he promoted it, he asked around on various association forums to garner the level of interest for those of us with M25 engines. Guess he didn't get enough feedback for EM to do what they are now doing for you. I would have loved to do so, but have zero clearance between the front of our engine and the companionway steps. Good luck, looking forward to your updates.

 

[Maine Sail]

Part of the problem E-Maax faces with the M-25 series is that it changed two or three times over the years.

I suspect the kit you have would fit an M-25 XPB but not an M-25 or M-25XP.... The M-25 XPB has three bolt holes in the crank pulley but the others don't..

Please let us know how this all works out and when they have the kit ready...

Do you have an M-25 or M-25 XP?

 

[dparilla]

It is the plain old M-25 (1986 vintage). I have been impressed wtih E-Maax so far. They are hoping to get the replacement pulley out to me in the next week. The water pump pulley and alternator (on a balmar 912) pulley fit perfectly.

 

[rajhnsn]

Why is this upgrade a good idea. Why not just replace the belt with the typical V cut belt?

 

[dparilla]

V belts are very limited in the amount of horsepower that they can transfer. If you are running a large alternator, say 90 amps, the belt will slip, alot. Plus any time a load is initially applied v belts momentarily slip. Mainly due to the limited surface area through which they make contact with the pulleys (the sides of the v). This slip and grab generates a lot of black rubber dust. A flat, ribbed serpentine style belt significantly reduces slippage, reduces the rubber dust, lasts longer, does not need to be tentioned as tight as a v belt, and can drive large alternators without having to add a second belt drive. Plus getting a tapped crank pulley will also give one the option of adding additional gear such as engine driven refrigeration, a water maker or even a second alternator. There are other reasons that serpentine belts make sense, just take a look at modern cars and even new boats and they have all gone to serpentine style systems. I am currently running a 90 amp alternator (and I can show you the black stripe of rubber detritus flung from the old belt), and may want to kick it up in the future as we spend more time away from the dock. To me it made sense to make the jump.

 

[dparilla]

DONE!

We are up and running. Only 3 minor issues throughout, and Emaax worked hard to get things done. First, I needed to change the original crankshaft pulley for one that is tapped to receive their cover pulley. Secondly, the crankshaft on older m25s accepts a .875 bored hole. The pulley received was bored to .870, so a quick trip to the machine shop fixed that issue. Then, we had to re-measure the belt. The stock alternator bracket will accept a 42 inch (420) belt, but the updated bracket (hangs the alternator with the tension arm below) takes a 40 inch (400) belt. So now that we have sent the specs to emaax they should be ready and able to build a kit.