HMMWV Serpentine Belt Issue - 6.5L

[Action]

Guys, I’m sorry if this is so basic ))) but I just bought a M1151A1 and a new serpentine belt, which I can’t install it ! Even if I go around the fan blades I hit the engine support bar…. Any advise? (Looked for all kind of videos and couldn’t find any for the M1151….

Is your fan at an angle under the radiator? If so, you can remove the 6 bolts that hold the short “driveshaft” to the pulley on front of engine.

 

[jake20]

I’ve got pretty much the exact same issue as the OP. M1043A2 with Sanden + Red Dot AC, 126” belt.

I ran the truck for about 4500 miles with no issues (the last 1000 of which I finally got the AC system running), then one day it throws a belt. I noticed it came off the AC compressor. What I also noticed is that my tensioner was actually at full loose extent the entire time, so the belt wasn’t all that tight to begin with.

The easiest option to tighten the belt was to move the alternator over by one hole towards the driver side, the top bracket has 2 position holes. This fixed my tension issue, the tensioner sits exactly between both stops now.

The Red Dot manual specifies that a second hole has to be drilled on the tensioner mount in order to clock it at a different angle, I also confirmed that this was done by whatever depot installed the system initially. It wasn’t required on all trucks but mine was part of the required list.

Fast forward 200 miles later, belt jumps a groove again towards the back of the AC compressor pulley. So the tension wasn’t the root cause.

Upon some very careful eye inspection, I’ve noticed that the compressor may actually be tilted downwards by the smallest amount. I don’t know how this is possible considering the brackets leave no room for adjustment, but you can very clearly see that the belt is offset when compared between the tensioner and water pump pulley. The belt also does ride at the complete aft-most edge of the tensioner.

I’m going to attempt adding 1 washer to the bottom compressor bolt and seeing if the belt stops riding the edge of the tensioner. Both times it has ridden up aft on the compressor pulley.

Pics attached, interesting riddle.

EDIT: Both times the belt has hopped off or jumped a groove, I’ve replaced it. I’ve got another spare ready to go but it’s not exactly fun changing belts in a parking lot lol

 

[jake20]

Update on my situation, it’s only been slightly resolved. After many different configurations with washers, I ended up doing the same stack of 2x washers per bolt on the bracket as OP @phemer

This solved my immediate issue of the the belt getting shucked off the AC compressor in only a few miles. Since the compressor sits further aft now, it’s not in a spot where it’ll want to jump a groove.

The issue now is that the belt is riding way too far aft on then tensioner pulley, and the edge of the belt is slowly eroding and showing the fuzzy fibers.

After staring at this and poking at it with straight edges for hours, I’ve come to the conclusion that there may be 2 alignment issues.

1: When viewed from the top, my AC compressor is yawed to the left. Hard to tell by just looking but I’ve checked with straight edges and I’ve even outlined it in the attached photos

2: I believe that my entire AC amount bracket may also be slightly pitched upwards compared to everything port-side onwards from the crank pulley, but this is less serious than #1

Given that you can’t adjust these brackets, I’m really not sure what to do short of just starting to modify the brackets with some welding/grinding/drilling. I would like to avoid going down that route but I also can’t have these belts eroding after just 1500 miles.

My other thought was to just dump this Sanden compressor and its red dot afterthought bracketry, and move to the new style delphi compressor that’s found in the ECVs, REVs. The only thing I’m not sure of with that option is adapting the new style fittings to Eaton Aeroquip.