Victim is a 84 which has had a 86 Duke + Isuzu transplant.

For the two years we drove on it before the transplant, the 84 drivetrain would go through roughly one v-belt per year. The 86 drivetrain can kill them faster than that; I doubt that there are more than 3,000km on the current belt. I may even have to change the bloody thing in the parking garage before leaving the office today.

The only component in common between the two drivetrains is the alternator & the lower alternator bracket. I upgraded the 84 to a CS-130 at one point during its life, and the 86's original bracket snapped when I made the transfer to the 86. I was suspicious that a slight difference in the lower bracket may have been contributing to pulley misalignment, but the 22P confirms that the lower bracket went unchanged from 84 through 86.

I don't recall noticing any elongation of the bolt holes in either the bracket, or the alternator body when I performed the transplant. The upper bracket does not appear to be loose or allow any play.

Pulley alignment is straight & true as far as I can tell by eyeball. A new belt will have no obvious curve or tangent in the transition from "free space" to where it contacts the pulley. I have yet to verify it with a straight-edge however.

Pulleys are clean, dry, and undamaged. I don't do belt dressing.

Not sure how relevant some of the following is given that some of the observations may be the result of the currnent (worn) belt, but...

Polished areas on both the crank and alternator pulleys indicate that the belt is making good contact across both sides of the V, although it has always sat a little deeper in the grooves than I care for.

Polished areas on the water pump pulley suggest that the belt is only making contact at the upper edges; i.e. at its widest part.

My current suspects, not in any particular order, are:

• I've been consistently provided with belts of the wrong size. Current one is a 11AV1270 Gatorback; considering tracking down a 12mm wide belt for shits & giggles given my dislike of the "installed height" of a 11mm belt.
  
• There is some serious pulley drag going on. Doubt it. The only pulley which doesn't spin freely by hand is on the crank. Not to mention that I would expect charging or cooling problems should either the w/p or alt. be showing enough resistance to constantly drag on the belt.
  
• One or more pulleys of incorrect size (width). I have NFC how to verify whether or not they're correct at the moment.

Insight, ideas, even some simple pointing & laughing in my general direction is appreciated.

[This message has been edited by dguy (edited 11-29-2005).]

I think you need to go the other way. Top width should be 9.5 mm (.375").

[This message has been edited by spark1 (edited 11-29-2005).]

Belt contact that is low on one pulley and high on another would suggest that one of the pulleys is incorrect. I would suspect the alternator pulley.

quote Originally posted by spark1: I think you need to go the other way. Top width should be 9.5 mm (.375").

Interesting... that would make it more or less disappear in to the pulley grooves compared to where the 11mm belt rides, I imagine. The best I was able to scrounge up from local parts stores on short notice however was a 12.5mm belt. I suspect it will ride a little higher than ideal, but so long as it has enough bite to keep everything spinning without getting thrown, it'll do for the trip home.

quote Originally posted by Tom Piantanida: Belt contact that is low on one pulley and high on another would suggest that one of the pulleys is incorrect. I would suspect the alternator pulley.

I agree, but I am uncertain as to which pulley to point my finger at. On one hand the belt-eating has followed the alternator from one engine to the other. On the other hand, it's the water pump's pulley which is showing less belt contact than that of the crank & alternator.

Note: the CS-130 did not come with a pulley--I had to transfer the 84's original pulley to the new alternator. At least that rules out a parts vendor and/or rebuilder pulley foul-up.

[This message has been edited by dguy (edited 11-29-2005).]

My original Duke had the same thing.. eating V-belts like MAD

I dug deep and found out that the casting for the alternator on the engines block is actually miss-drilled at an angle right from the factory !

Checkout these pictures:

The tilted casting right on the block that was eating the belts because of mis-aligned pulleys.

and the correction made to the aluminum alternator bracket that CURED it... (oxide flapper and many test-fits)

Because of the extra material on the alternators aluminum mount (little humped area) it was more feesible to just adjust it to be straight instead of trying to grind the block... (not an easy spot to reach eh?)

It's not hard, Pull the alternator clean out of the car and leave the bracket ON, Then compare it with a straight-edge and see if you get what I had.. Mine was a little more obvious.. Yours may be as well..

hope this helps..

Rob

[This message has been edited by BERKELUSA (edited 11-30-2005).]

Wherever you have those photos hosted is blocked from here (work), but I'll check it out when I get home. Thanks for the tip, Rob!

...and as a follow-up:

quote Originally posted by spark1: I think you need to go the other way. Top width should be 9.5 mm (.375").

Well apparently the 11AV1270 is 9.5mm wide. I could swear that once upon a time when I was working in a dealership parts department that belt #s were an indication of width & length, but apparently no longer.

The belt should sit in all the pulleys just like it does the crank pulley. Running high only in the WP pulley means you are using the wrong pulley or the wrong groove. (My 86 has 3 grooves if I remember right.)

From the numbering I can remember...
11 ?
A = A profile (B profile is much wider.)
V = V belt
1270 mm

Most cars main V belt is an A profile. Some cars with smog pumps use a thinner profile to run just the smog pump. I don't know of any cars using B profile belts.

You assume that because you can't feel binding when the belt is off that nothing is binding... This is a typical mistake. Take the alternator off and have it tested on a bench machine. If the pulley is binding under load this may help detect it. (Bench test machines offten don't run at full belt load.) if the WP or alt bearings make any noise at all when spun by hand then the bearings are going bad and could easily be binding with belt load.

V belt alignment can be quick checked with a small diameter lazer pointer. Find on that will sit into the groove a bit. If it won't sit stable, you'll have to glue a block to it. The pain there is the block has to fit the pulley AND be square with the lazer beam.

Do not assume the pulleys are clean. Clean them using something that won't leave residue. No oil based solvents. Something that will strip wax as well as dirt/oil.

Belt tension is another common screwup. Having a belt too tight will kill them as sure as too loose. Get a belt tension gauge and stop guessing. google this "belt tension gauge" including the quotes. see also gates krikit

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quote Originally posted by theogre: The belt should sit in all the pulleys just like it does the crank pulley. Running high only in the WP pulley means you are using the wrong pulley or the wrong groove. (My 86 has 3 grooves if I remember right.)

Only one groove here...

In any case, I may have misinterpreted the polished areas of the w/p pulley with respect to belt contact. The new belt which I installed a few days ago rides at the same hight in all three. The different polish pattern I initially observed may have been a result of the badly worn belt.

quote You assume that because you can't feel binding when the belt is off that nothing is binding... This is a typical mistake. Take the alternator off and have it tested on a bench machine. If the pulley is binding under load this may help detect it. (Bench test machines offten don't run at full belt load.) if the WP or alt bearings make any noise at all when spun by hand then the bearings are going bad and could easily be binding with belt load.

Bearings on both the alt. and w/p are silent, fortunately. If pulley alignment, pulley cleanliness, and belt tension check out I'll have the alt. bench tested.

quote V belt alignment can be quick checked with a small diameter lazer pointer. Find on that will sit into the groove a bit. If it won't sit stable, you'll have to glue a block to it. The pain there is the block has to fit the pulley AND be square with the lazer beam.

On this weekend's to-do list, actually.

quote Do not assume the pulleys are clean. Clean them using something that won't leave residue. No oil based solvents. Something that will strip wax as well as dirt/oil.

Brake Cleaner. 1001 uses.

quote Belt tension is another common screwup. Having a belt too tight will kill them as sure as too loose. Get a belt tension gauge and stop guessing. google this "belt tension gauge" including the quotes. see also gates krikit

Excess tension was actually a late-breaking suspect. Prior to this particular engine I had always tensioned v-belts by feel; never had a single problem with belt failure or bearing damage. Out of paranoia when installing the recent replacement, I checked what Haynes recommended. There I discovered that the deflection they called for (about 1/2" at the center of the span between the w/p and alt.) was roughly double what I was allowing using my old method.

I'm still going to verify the pulley alignment & clean the suckers, but I have a subtle feeling at the moment that I've been screwing myself with my own equipment.

Get a small wire brush, a nice fresh clean one, and use that with the brake clean to make sure any film is scrubbed off. The ones you want look like over size tooth brushes.

When I last cleaned my serpent pulleys they looked ok after washing with 409 and water. Then I scrubbed them with the wire brush and more crap yet came off them.

Shive alignment on the shorter runs is really critical. Even more so with serpents but V belts will also suffer higher wear over s short run vs a long run with the same amount of error.

A common culprit on the L4 is the water pump pulley being pressed out of alignment. Last time I had the pump done and they didn't press it all the way on. This time I did it and could press it as needed to make sure it lined up with the AC and crank. (Remember 87 is a serpent so only one belt runs everything...)