Can't remove old alternator belt

[m_galligan]

I'm trying to do an alternator belt replacement. The drive pulley comes within an eighth of an inch of the engine block, and I can't get the belt out in that little space.

I saw Don's comment from a couple Decembers ago:
> There's nothing hanging on to your belt other than a layer of crud on the side of the engine (between the pulley on the accessory drive and the engine). In ideal circumstances, the belt will practically touch the outside of the pulley and the side of the engine, which means that any build-up of crud will prevent the belt from coming away from the pulley sufficiently to remove it. We sometimes have to scrape the side of the block with a putty knife before the belt will come off.

Is this (scrape the crud, rust and scale off the engine block) what people do? Or do they remove the pulley? Or is there some other useful trick?

-Marty

[tenders]

I've occasionally had this problem. My solution is to remove the bolt on which the alternator pivots so the alternator itself comes off the engine. You don't need to take it away from the engine--just twist it a bit, allowing the old belt to slip off and giving you a few degrees of freedom to maneuver the new belt into place.

Removing the pulley with the alternator in place is pretty difficult. I think the torque spec for that bolt is 100 ft-lbs.

[msauntry]

???
Is this an early model A4? Mine is a late model and I've got plenty of room around the accessory drive... I had no idea they were that different.

I would measure your pulley to see if it is stock. Heck, regardless of the stock size, I'd get a smaller pulley so it isn't such a chore! This will spin the alternator a little less, but I don't think your charging will suffer. You have to loosen the alternator anyway to remove the belt, so just to clarify, you are talking about the Accessory Drive pulley?

[tenders]

With the stock belt, there is not a lot of slack in the range of movement for the alternator between "tight" and "loose enough to remove." Perhaps some boats have longer belts which would give more range of movement?

With a '76 boat this is probably a late model A4. I believe he's referring to the pulley on the alternator, not the one on the engine. It's removable, but there's an easier way.

It only takes a minute or two to take the pivot bolt out. (That's not the bracket bolt you tighten to hold the tension on the belt--it's the one that holds the alternator to the engine.)

On my engine, the nut and the head of the bolt are different sizes so you can use two different wrenches on it. I even wrote the size of the necessary wrenches on the alternator with a Sharpie to make this even more straightforward.

[m_galligan]

lower pulley

I'm trying to get the belt off the accessory drive pulley, located 8" below the alternator. (I've loosened the alternator pivot bolt on top, and removed the alternator bracket bolt. Also removed the alternator bracket and water jacket side plate, but that's another story.)

So, with the alternator belt completely loose, I can't squeeze it out between the engine block and the drive pulley. The engine is a late model.

-Marty

[Kelly]

I think this is the spot where your belt is getting stuck. The belt should be removable with no undo effort. Perhaps the belt swelled or wore in such a manner that it is now thicker than at installation. If this is the case, you could cut the belt and replace it with one that will fit in the space.

Maybe the pulley has a larger diameter than normal and the belt was installed with the pulley removed...

Go figure.

Best of luck,
Kelly

[Don Moyer]

You either have a non-standard (wider than normal) belt or there is a layer of crud built up on the block. The belt must have gone on in the past, so it should come off now.

Don

[msauntry]

Anybody know what the stock diameter of that accessory drive pulley is?
(I'm miles away from mine.)

What's involved in removing the pulley and putting in another?

I'm guessing a previous owner has put a bigger pulley on Galigan's engine to get better alternator charging.

[tenders]

> I'm guessing a previous owner has put a bigger pulley
> on Galigan's engine to get better alternator charging.

Possibly. But, especially considering the narrow clearance, an easier way to do get the same effect would be to use a smaller pulley on the alternator.

Seems more likely to me that a previous owner used a belt that was too thick. Wedging the loosened belt into the gap and bumping the starter won't flip that sucker outta there? If not, I'd just cut it and assess from there.

[adab1402]

alt belt replacement

cut the old belt and roll the new one on while you turn the engine by hand . fair winds

[Don Moyer]

It's very unlikely that anyone could have found a larger pulley to fit on the accessory drive. These are special pulleys designed with a shoulder that extends in to ride on the oil seal in the front of the housing. Additionally, there is so little space available for a larger OD pulley that I can't imagine anyone going to the effort (and expense) of having one specially machined. Having said that, the pulley will usually tap off quite easily once the 5/16" (1/2" hex-headed) bolt is removed from the shaft, so removing the pulley would certainly be a reasonable option.

Don

[SEMIJim]

Perhaps the OP's problem is getting the belt off the pulleys? I had that problem. What I had to do was get it partly up on the shoulder of the bottom pulley and work it off the rest of the way. Same thing, in reverse, getting it back on.

The next problem I had was getting it out from around the alternator, itself. IIRC, I had to raise the alternator up all the way to sneak the belt out.

Jim

[msauntry]

Go into Napa and ask for a 3/8" wide, 26" long green belt. These go on very easily.

I'm curious if the difficult belt a 1/2" wide? I can see how the extra meat of that would cause problems now. If you've got a non-standard belt, just cut it off and put on the proper 3/8".

[m_galligan]

I'm the "OP". I got the old belt off last night. I think the belt (not the pulley) was non-standard. Not that I know for sure what the standard is. But the old one was 3/8" thick (from id to od, when in normal operating position), and the new one is only 1/4" inch thick. I've got a lot of confidence in the source for the new belt so I'm assuming that the new one is the correct size. To get the old one off the successful method was (as suggested above) jam it halfway off, snug between the engine and the pulley, and turn on the ignition for a half second. The second time the belt came off.

I still don't have the new one on, but that should happen tonight or Sunday. My pulley measures about 3-5/8" diameter, although it's hard to get the tape measure reading accurate.

[msauntry]

I guess we should have suspected the most obvious cause-- wrong belt vs. wrong pulley.

Copied from the Alberg 30 site:
The alternator belt is 3/8" wide and 25" around (approx. 12" long when flattened). The size may be marked 1 cm x 63.5 cm. Alternator belt
-Drive King 3L250 "Fractional Horsepower V-belt"
-Gates HC-3VX-250 or #7250
-NAPA Belts 25-06353
-BFG Maxipower 3V250 57 ORS-M
-Goodyear or Kelly/Springfield 10AV0635
Hopefully these numbers are still valid.

If you look at Don's Mando alternators, he recommends getting the 26" belt instead of the 25".