CUCV fan belts for m1010

Does anybody have the part number for the napa fan belts, takes 4 belts? T.E. Muddy Thank you!

I have info for two of the belts, they should be able to look it up:

Top alternator belt, 42-6919, .5 width, 59 inches outside length. V192MP?

Bottom alternator belt, 42-6921, .650 width, 51.250 inches outside length,

Here are the O E part numbers. NAPA should be able to crossreference them.
42-6919 Upper Alt
42-6921 Lower Alt
42-5023 PS
42-4877 A/C

Got these useful numbers out of the parts TM available free in the manual section.

Try the CUCV Wiki at the top of the forum page, all the part numbers are there...

thanks for the information on the fan belts, i got them at napa, but i haven't put them on yet. M1010 temuddy, marietta, ga

Gleaned from the TMs and wbparts.com:

This always works for me on my CUCV's . I go to the parts store with all the tools to change the belts and just walk in and out with random belts that are close to the ones I take off. I change them in the parking lot and and have the full selection at my finger tips. I can choose if it is to tight or to loose right there. Most times I try to get a belt that has lots of adjustment left in it. Most belts listed here have little or no adjustment left in them right after you put them on. On a CUCV I learned a long time ago. If the belt squeaks when you start the truck tighten it right away. It is just ruining itself and don't take long till it is junk. A 1/16" is important to belt tension. Don't let guys tell you that's normal right after I start it. It is NOT normal. Do you think GM and the military would have accepted a vehicle that did that as normal. NOT. Fix the squeal ASAP. Change the belts so that they are tight when the bolt is all the way back in the loose adjustment slot. Take my word for it. NO SQUEALER here. I find that the same belts do not fit the same CUCV. I don't know why but they don't and it don't matter. I am not an engineer. I am a guy that fixes things so they work. Not by changing the world by fixing the existing problem and getting the CUCV back on the road. I hope that helps with your belt dilemma.

cucvrus said:

On a CUCV I learned a long time ago. If the belt squeaks when you start the truck tighten it right away. It is just ruining itself and don't take long till it is junk.

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On my M1010, loose belts don't squeal, except perhaps the power steering belt when I turn the wheel to the stops. On the other belts, I get a sort of "thrum... thrum... thrum" sound. It took me a while to figure out that that was coming from loose belts.

I had new belts put on 2000 miles ago. The alignment guy noticed that one had rubbed a hole in my lower radiator hose. He said it was because the belt was too loose. I got a tool to measure tension, and confirmed they were all below 50 lbs tension, when the TM calls for 67 lbs.

I tried tightening them, but there wasn't enough adjustment left to pull them tight. OK. I figured the guy put on too-large belts. So I took the cucvrus approach (photo), got a bunch of belts and put on the smallest belts that I could install. On the alternators, I replaced a 52" belt with a 51" (lower), and a 59" with a 58.5" (upper). That was less of a difference than I expected. It turns out the guy wasn't far off in the belts he installed. I guess I just failed to re-tension them after they "broke in". Evidently, running them loose stretched them out to the point where there was not enough adjustment.



I know the belts in the photo are cheap. It's what's available locally. I'm using them to get the sizes nailed down. Then I'll order good belts in those sizes. The good news is my alternator belts finally have the proper tension.

So for my M1010, the stock lower alternator takes a 17510, but you have to struggle a bit to install it. The upper alternator is the 12V Plan B Mod alternator. It takes a 17590. You can get a 17585 on, but you have to dismount the alternator to do so. This is exactly the belts the TM called for.

I'm also having tension problems with the PS and A/C belts, but there's plenty of adjustment left there. I guess the belts just keep stretching. I'll keep adjusting them until they stabilize. Then, when I'm sure I have all the sizes right, I'll upgrade to better belts.

What torque do folks use when tightening down the belts? I'm not finding that listed in the TMs or cheat sheets... The standard torque for 3/4" bolts is 185 ft-lbs. Does that sound right for the alternators?

The belts you show are fine. I used them many times without fail. Autozone and all the other national parts stores are all the same. Don't let other fool you. It is a personal preference of which is better. I do use Gates belts and hoses at times. What ever works. Keep them tight and if they squeal adjust them. I never had a belt tension tool. Never used one. I tighten them till they stop squealing. May be bad advise but it works. All these fancy tools were not available to me when I grew up as a poor farm boy. We just got by. As I grew up I still was able to do more then most with less and still have nice functional things without having a boat load of money tied up in the vehicles. Some people see junk and I see opportunity. I have made a few silk purses out of sows ears. And turned them into running machines for years of hard use. Others try to make them into show boats and screw up the whole vehicle and it becomes a scrap pile that is so screwed up it is not worth the effort. They use this guys method and change this and that and they have a secret vehicle that no one including themselves know how it works or how to fix it. I see it all the time. I ran a lot of good vehicles thru the shop that ended up being scrapped and never fixed. I don't think alternators have a 3/4" bolt on them. They may have 1/2" bolts with a 3/4" head. But that is a lot of torque to put on an alternator bolt. I torque head bolts, intake bolts and other vital bolts. I just tighten alternator bolts. Once again it may be wrong but it works and I never had any failures for lack of torque. I know every bolt has a torque but I don't spend all day being a technical worm on bolt torques. I diagnose the issue and fix it. You are doing a fine job. Continue and keep up the good work. I am glad I could give you a wee bit of assistance in your quest for belts.

cucvrus said:

I don't think alternators have a 3/4" bolt on them. They may have 1/2" bolts with a 3/4" head. But that is a lot of torque to put on an alternator bolt. I torque head bolts, intake bolts and other vital bolts. I just tighten alternator bolts.

Click to expand...

Thanks.

You're right. I was confusing bolt size with the size wrench required to turn them. That seemed like an awful lot of torque to me. I'm glad I asked before trying it. I just tighten the alternator bolts as much as I can using a 1/2" socket wrench. They keep getting loose, so I was thinking it might be inadequate torque, rather than stretching belts.

I have a history of breaking things, snapping bolts, etc. So I use torque wrenches a lot. I know a lot of guys can test belt tension with their thumb. I may get to that point, and the tension tool will help me get there. It's only a $12 tool, so worth it to me. I also want to leave my daughter able to check belt tension, so the tool will be for her too.

I'm not sure why my belts never squeal, I've learned to listen for the "thrum... thrum..." of a loose belt, and to check them regularly, especially when new.

Thanks again for all your help.