F134 Belt Setup

Hello,
I have a M38A1 with what I think is a civilian F134 engine. It has a 12v system with an alternator installed. When the previous owner bought the jeep it didn't have the fan on the engine. It had an electric fan in front of the radiator. He purchased and installed a fan on the engine. However, it appears the fan belt cannot be tightened. The fan spins but the belt is loose and noisy.



There appears to be a double pulley on the crankshaft. I'm thinking it might be of the type for an external governor? My thoughts are to acquire a larger pully for the alternator and move it forward a bit and run both accessories on a single belt. Am I missing anything? Does anyone have any suggestions?

Thanks,
Ken

 

On my F134 I have one belt: My alternator, water pump/fan, and crank pulley. I adjust tension in the slotted arm that the top of my alternator is mounted to. I would do as you say and move your alternator front so that you can run on a single belt. Could you flip it around to the front side of the arm? My crank pulley has two grooves as well but I am only using one.

 

What is the reasoning behind the double pulley on the crank anyway? Just curious.

 

Thanks for the replies. I have a correct belt on the way. Given some time tomorrow I'll take a closer look at that alternator mount and see if I can move it forward. I understand the correct belt is 5/8". Is that also the inside with of the pullies? I should check the crank and fan pullies to make sure they are the correct size and also order a correct one for the alternator.

I'm thinking the crank pully is from this type of setup. Does that sound correct?

 

Double pulleys all round and ("matched") twin belts were the M38A1 set-up.

 

I just installed my alternator a week or so ago...I used brackets and a pulley from Willys Works in Arizona. pretty straight forward set up. im very happy with the parts!
The stock belt may require a bigger pulley on the alt.

 

If your were to find an M38a1 double fan pulley, that would be the easiest solution. Then if you found a double alternator pulley, you could even run the correct pair of belts.
-Donny

 

Your current set up has no way to adjust or tighten the fan belt. Unless there is something I'm not seeing there, you'll never get it to work.

As some of the others mentioned, the M38A1 had double pulleys on crank, fan/water pump and generator. It was a heavy duty set up. On my A1, the PO changed it to 12 volt but kept a double pulley for the alternator.

If you don't want to move your alternator out, you'll need to get an M38A1 double pulley water pump. Find it on ebay, 1/4 Ton Military has them. It sounds like they are quality, US-made parts and should solve all your problems. Avoid the omix stuff even if it's a few bucks less.

 

Here we see how this forum is the best one...

 

Thanks for all the replies. I ended up getting a larger pulley for the alternator and moving it forward to be in the same plane as the water pump. I'm running one 5/8" belt. Seems to be working so far.
Upon closer inspection I think the crank pulley is the large/small combination for a governor. So using the forward pulley with a large belt works.

 

Or rig up a belt tensioner like the one in the caravan V-6.

Probably picik one off of any after 2000 car or pickup. or van.