altenator belt

[nyiftos]

Good morning again from afar,
1972 Pearson A-4 engine, new version.
what is the proper way REPLACE an altenator belt?
Looked in and around there, not much wrenching room.
The belt will not fit thru block and pulley, is the water pump drive shaft also an issue that will be in the way?
thank you

[Mo]

I put the belt on and squeeze it tightly in around the pully so that it will roll on, in the direction of engine rotation. So, you are starting the belt on the pully...then if you click the starter it will pop it in there. I've never had an issue with a belt ... current one went on like that and has been on there about 4 yrs.

[roadnsky]

To add a bit to Mo's instructions...

On my Accessory Drive pulley there is just enough room to slip the belt on.
It's tight but you can ease it through.

You should also loosen the alternator tension to make it easier to get the belt on the alternator pulley.
Of course, it's even easier to do if you have the handy MMI Alternator Tensioning Arm!

[nyiftos]

alt belt

Hi guys,
ok I will take a mirror, a flashlight and inspect closer the area of the alt. and accessory drive pulleys.
Thanks for the photos as well.
It does not need the belt at this time but my paranoid mind needs to know how and be somewhat ready if the need ever be.
Do you know the size or number of belt it takes?
I will write again after further inspection of area.
Thanks

[roadnsky]

Do you know the size or number of belt it takes?

That will depend on your Alternator and set up.
Do you know which alternator you have? Motorola 35A? 55A?
Can you post a pic?

Likely size is 25" or 26"...

[Al Schober]

Just did mine two days ago - Gates 6725 for my 60 amp Delco. Replacement was a 'blue' belt from the hardware store - $12 for their best! Fit between the pulley and the block with no issue. I'm still trying to figure out why I need that spring loaded thing..

[ndutton]

I'm still trying to figure out why I need that spring loaded thing..

Maybe you don't, it's not really a necessity.

Even though it's called a "belt" tensioner and it does actually tension the belt, what it's intended for is to avoid overtightening the belt and therefore wearing it out along with bearings (alternator or auxiliary drive or both) prematurely. Belts are cheap and easy to replace. Bearings on the other hand . . . . .

How tight is your belt? How tight should it be to perform properly?

The spring loaded tensioner isn't for everybody. The serpentine belt guys like them pretty well though. Have a look under the hood of your car for an example. Since the introduction of automatically tensioned serpentine belts accessory bearing failures have become a rarity. The greater circumference the belts are in contact with the pulleys is a factor but so is the proper tension.

We don't really "need" electronic ignition either or fresh water cooling, extendo bolts, adjustable jets, etc.

[Mo]

Just did mine two days ago - Gates 6725 for my 60 amp Delco. Replacement was a 'blue' belt from the hardware store - $12 for their best! Fit between the pulley and the block with no issue. I'm still trying to figure out why I need that spring loaded thing..

They use pretty much a 25 inch belt. I have a Delco 100 amp on there.... If you purchase the thinner belts they will generally fit in there. If you purchase the more robust belt (which I use) you will have to partially start it on the pulley and click the starter to load it...but it goes on without damage.

[hanleyclifford]

Just did mine two days ago - Gates 6725 for my 60 amp Delco. Replacement was a 'blue' belt from the hardware store - $12 for their best! Fit between the pulley and the block with no issue. I'm still trying to figure out why I need that spring loaded thing..

I run dual belts and after 3 trys to get a matched pair of the "best" at NAPA and elsewhere I finally found an ACE in Brigantine that sold lawn equipment; bought a pair of cheapo Mitsubishi belts not even claiming to be "matched", but they were. That was 4 years ago and I firmly believe the reason they're still kicking is that "spring loaded thingy". Just sayin'

[StephenGwyn]

How long do belts typically last?

My current alternator belt is starting to squeak after 10 years/900 hours. I bought a spare at the same time as the current belt. I was going to install it, but quite frankly, I can't tell the difference between the installed belt and the spare. Both are bit on the stiff side. The used one is very slightly more ragged, but that's about it.

Do belts deteriorate when they're just sitting in the spares locker?

[hanleyclifford]

How long do belts typically last?

My current alternator belt is starting to squeak after 10 years/900 hours. I bought a spare at the same time as the current belt. I was going to install it, but quite frankly, I can't tell the difference between the installed belt and the spare. Both are bit on the stiff side. The used one is very slightly more ragged, but that's about it.

Do belts deteriorate when they're just sitting in the spares locker?

I believe they do. I suggest you install the "new" one and keep the old as a spare. I do this with everything - belts, starters, distributors; you might say "dynamic spares".

[sastanley]

Stephen, I agree with hanley...the problem with buying a spare with the primary is they both age at the same rate...and definitely I think they age in the "spares locker".

As I am acquiring parts, if I am lucky enough to buy a new part, I generally install it, and keep the old working part as a spare since I know it worked. A "spare" is designed to get me home in the event of a primary failure.

Exceptions are fuel filters, spark plugs and similar..

[RobH2]

Maybe you don't, it's not really a necessity.

Even though it's called a "belt" tensioner and it does actually tension the belt, what it's intended for is t. . . . .

How tight is your belt? How tight should it be to perform properly?

The spring loaded tensioner isn't for everybody....

I'm curious what the proper method is to determine if the belt is the correct tension. Is it deflection in the center? If so, how much? I just want to make sure I don't wear out my bearings. I've pulled and reinstalled my alternator recently.

[ndutton]

I'm curious what the proper method is to determine if the belt is the correct tension. Is it deflection in the center? If so, how much? I just want to make sure I don't wear out my bearings. I've pulled and reinstalled my alternator recently.

Belt deflection has been the old school shade tree method but its accuracy is greatly affected by belt size, style and the span between sheaves. During the development of MMI's tensioner we used an already established torque value borrowed from Lycoming aircraft engines. Their tension specification states the sheave should not slip with 12 ft-lbs of torque applied. The instructions for MMI's tensioner require you to compress the spring a prescribed number of turns of the adjusting hex nut that by testing we found to apply the correct tension.

Interestingly, I had a belt squeal episode at one point. I tightened the tensioner adjustment a little and it still squealed, tightened it more with the same result. It turned out the belt was worn and replacing it brought everything back into spec. In other words, if you experience a belt squeal at the prescribed tension, it's time to replace the belt.

[RobH2]

Ok, good enough. Thanks for the info.