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Serpentine belt trouble

BoondocK5

BoondocK5

Chevrolet Bone Collector
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On my 8.1 liter, I adapted in an AC compressor using custom built bracket that came off a Kodiak truck. It was a left side AC bracket, I converted it to a right side bracket.
So the problem, I can’t keep the belt on the AC compressor, it wants to push itself off towards the compressor. I’ve tried spacers under one end of the other of the compressor. I still can’t get it to stay on the compressor, there is no happy medium.
I think I may have to build/manufacture a bracket that kind of keeps/directs the belt into the pulley

Any suggestions from the brotherhood?
 
What do you have now for a tensioner? Have you measured the alignment?
 
I’ll get pictures this afternoon. I’ve got a stock 8.1 liter belt tensioner.
Everything looks aligned. I’ve laid a straight edge across the pulleys at different places, everything appears aligned.
It is for sure a different setup than GM ever had in mind. I had to use a belt from a Nissan with the Cummins diesel. It is the only thing with enough length
Pics to follow.
 
Yeah I need a pic as my mind can’t picture what you have going on.
 
Is the tensioner in the middle of its range with that belt or maxed out? (Sometimes they have marks, but you can always put a wrench on it. What's the distance from the compressor pulley to the next thing? It looks like a pretty long run. When the engine is running, can you see belt flap?
 
I think I may be on to something.
After I replaced the positive battery cable to the starter(I had apparently attached the positive battery cable from the starter on the negative bus bar, instead of the B+ bus bar) with a freshly made battery cable. This time attaching it to the positive bus bar. I could turn the engine over and I watched the first pulley to pop the belt off was the belt tensioner pulley, I put it back on, then cranked the engine over while holding a large flat blade screw driver down near the tensioner pulley, kind of directing the belt back onto the pulley, it stayed on as long as I held it there with the screwdriver.
 
Blue85 said:
Is the tensioner in the middle of its range with that belt or maxed out? (Sometimes they have marks, but you can always put a wrench on it. What's the distance from the compressor pulley to the next thing? It looks like a pretty long run. When the engine is running, can you see belt flap?
Click to expand...
Engine doesn’t run yet. I haven’t installed the fuel tank or lines from fuel tank yet.
Yes tensioner is about in the middle of its range of movement
 
So is it kicking the belt off the tensioner to the engine side off the backside of the pulley or the front side to the fan?

It would tell me which way your compressor mount is off by.

I know there is a dedicated laser based tool to line up pulleys, but I think a cheap laser pointer could help by sighting to the next pulleys on either side.
 
ZooMad75 said:
So is it kicking the belt off the tensioner to the engine side off the backside of the pulley or the front side to the fan?

It would tell me which way your compressor mount is off by.

I know there is a dedicated laser based tool to line up pulleys, but I think a cheap laser pointer could help by sighting to the next pulleys on either side.
Click to expand...
Off the back side of the tensioner, towards the engine. Like I said, it looks like it’s tracking off the tensioner pulley backwards toward the engine, which causes the belt to ride up over the backside of the AC compressor pulley.
If I get over the top of the entire set up, it all looks straight inline. Obviously, something is amiss.
I think, I’m going to manufacture a small “guide”, a flat piece of metal, 3.5 inches in diameter. Drill a hole dead center, and bolt it to the back of the tensioner pulley. It will basically act as a backstop to keep the belt from riding off the pulley, which will keep it on the AC compressor pulley.
 
If it's coming off with just the starter motor, something is really off. Your mount may have the compressor at an angle. If you can get an angle finder on the clutch and the crank, that verifies in that direction, then a straight edge should show if it parallel to the front of the block. https://www.gatesaustralia.com.au/~...anincreasebeltdrivewhitepaper-performance.pdf

I don't think you want the belt riding against a stationary object. If you make a guide, it should be part of the pulley, so it's turning. At least as proof of concept, you might be able to swap the smooth tensioner pulley for a ribbed one, since they have sides on them. But still, any misalignment of pulleys will make the belt wear out faster and the noise may be obnoxious.
 
On something like a band saw the guide is usually a bearing, not a flat plate. Dealing with thrust on the side of the belt without a bearing is going to produce heat, noise and wear. You should be able to align the belt without any special guides, just the right alignment and correct pulleys.
 
I had a thought today.
My semi-custom made AC bracket is made from a Kodiak LH AC bracket, just moved to the RH side of the engine. The tensioner is also mounted on that same Kodiak bracket. Anywho, if I remember correctly, the Kodiak/medium duty truck brackets and pulleys all were a bit farther away from the engine than the light duty brackets and pulleys.
This is my problem.
That bracket is actually holding the compressor father away from the engine than the rest of the pulleys/ brackets, which are all 2003 Silverado parts.
Which would pull the belt towards the engine, the exact problem I’m having.
Will confirm ASAP

What made me think of this was the memory of mounting that Kodiak bracket on when it was a complete LH bracket. It turns out that none of the Silverado equipment would line up with it. Namely the crank pulley. Which I am using now. So, I’m fairly convinced, this is my issue.
 
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That’s the problem. The pickup suv pump and balancer are shorter than the medium duty stuff. It will be a complete mismatch for sure.
 
Assuming you have an alternator bracket like this:

1734621788662.png

And the A/C bracket like this:

1734621817691.png

You should be able to measure the distance from the side of the head to where the pulley sits on both of them and the difference is how far you need to move it back. Also, if it doesn't directly hit your A/C, you could re-install the light truck tensioner in it's spot just above the water pump and have a side-by-side comparison with your A/C pulley.

The original issue is that using the light truck compressor mount puts the compressor in the frame rail?
 
Blue85 said:
Assuming you have an alternator bracket like this:

View attachment 493578

And the A/C bracket like this:

View attachment 493579

You should be able to measure the distance from the side of the head to where the pulley sits on both of them and the difference is how far you need to move it back. Also, if it doesn't directly hit your A/C, you could re-install the light truck tensioner in it's spot just above the water pump and have a side-by-side comparison with your A/C pulley.

The original issue is that using the light truck compressor mount puts the compressor in the frame rail?
Click to expand...
Yep, it’s the brackets. I’ll get to it asap. Lots going around the holidays now, especially with Melinda’s Cancer business still happening. At least we found an answer

Yep, don’t like where the light truck bracket put the compressor. I’ve had to cut way too much stuff, and the frame right there would have been more I wanted nothing to do with
 
Why buy a fabricated bracket when you have the real one? If he wanted to swap all of those parts over, he could probably return that bracket to LH duty. The question is what makes the most sense at this point.
 
I chopped up the Kodiak LH bracket and welded a few pieces back on it to make it a RH bracket.
The part I had forgotten was that the light duty and heavy duty parts have a different front to rear setback.
 
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