Checking alternator alignment

[westernman]

Everywhere you read about regularly changing belts for your alternator and then checking alignment. Been there done that. The alignment of my alternator and it leaves a bit to be desired.

So what now skipper?

Not one of the places where I have read about checking alignment tells us what to do when it is out of alignment.

So any better ideas than trying to put in a thin sheet of aluminum to shim it back to a proper alignment?

 

[pvb]

Often done by adding washers to the alternator mounts.

 

[westernman]

Often done by adding washers to the alternator mounts.

I don't see how. I have a standard Yanmar style mount which is a single bolt on the foot which serves as a pivot and an attachment at the top to a tensioning arm. It is the bottom mount which determines the alignment.

 

[macd]

I don't see how. I have a standard Yanmar style mount which is a single bolt on the foot which serves as a pivot and an attachment at the top to a tensioning arm. It is the bottom mount which determines the alignment.

In terms of shaft parallelism, yes. But surely the alternator can be shimmed on the bottom mount to correct out-of-plane misalignment. If that is done, it would be prudent also to shim the adjustment arm by the same amount.

 

[pampas]

easy way to check for trueness. bend a short piece of say 3/8" steel bar in the L shape. feed in till the drive pulley the L against the alt. pulley if true the long end should drop in the pulley easily, if out it will touch one side and not sit properly in the pulley. easier to do than to describe, with practice you will know when it is correct, also it tells you which way the alt has to be shimmed.

 

[LadyInBed]

"bend a short piece of say 3/8" steel bar in the L shape."
A long straight edge across the face of one pully and protruding across the face of the other pully is the way I do it.

If you can't shim the alternator pivot, you will have to remove and shim one of the pully wheels.

One other thought, remove the alternator and check that the pivot holes have not elongated, that's what happened to me.

 

[Hadenough]

I had the same problem resulting in black dust and short belt life. Fitted one of these -
http://www.asap-supplies.com/marine/link-belts-v-belts-vee-belts-polyvee-belts
Problem solved :encouragement: that was five years ago and it still shows no sign of wear.

 

[westernman]

The problem is I have checked the alignment and it is not great. I know how to check. Lots of places explain how to check. But not one tells you how to fix it!

 

[PaulJS]

If the pulleys are parallel but out of plane you need to either shim the alternator mounts to shift the whole alternator forward or aft, or move the position of the pulley on the shaft.
If not parallel you need to twist the alternator relative to the engine. If bolt holes are enlarged the quickest and easiest way is to use a lever to get it parallel and tighten the bolts while holding it in the correct position, and then adjust the pulley on the shaft to get it in the same plane as the engine pulley.
Takes longer to write than do! Assuming that the pulley isn't seized on the shaft...
Good luck.

 

[lw395]

The problem is I have checked the alignment and it is not great. I know how to check. Lots of places explain how to check. But not one tells you how to fix it!

I sawed a bit off the bracket where the alt pivots, then shimmed the other end with washers.
If the bracket bolts on to the block, then slotting the hole or re-drilling might be the way.
You can add a shim under the alt pulley to move it out.
Look for different alt pulleys.
Maybe you can file a chunk off the alt. body?
How bad is it? I think v belts can cope with being a bit out of plane?

 

[alanojones]

I had elongated mounting holes and had to shim the holes with cut down pipe. Then got a man with a air powered wrench to take the nut off the alternator pulley. I could mess about with different sizes of washer until it was exactly in line. Tightening the pulley in-situ was a pain, but once it's done it can be forgotten. I couldn't understand why it was never done before.

 

[westernman]

It is in line, but twisted. Quite possibly due to a worn mounting hole.
This method of mounting an alternator is stupidly crude. Much better some thing which holds it soldly in place on all four corners and where the belt tension is set by a belt tensioning thing on a spring.

I don't have the equipment needed to redrill the mounting hole (at least not anything like straight and true). I can't think of anything better than trying to shim it with a small thin bit of aluminum sheet on the flat surface.

 

[wotayottie]

I don't see how. I have a standard Yanmar style mount which is a single bolt on the foot which serves as a pivot and an attachment at the top to a tensioning arm. It is the bottom mount which determines the alignment.

You will find that the pulley on the alternator can be shimmed or have shims removed

 

[LadyInBed]

"I don't have the equipment needed to redrill the mounting hole (at least not anything like straight and true). I can't think of anything better than trying to shim it with a small thin bit of aluminum sheet on the flat surface."
I went through the same sinario, an engineering works talked of aluminium welding the holes and redrilling. I thought hammering in a tube and redrilling square would work, but in the end the easiest and cheapest solution was to order a new forward alternator face plate and get it fitted.
PS Isn't there a local garage that could point you to an auto electrician?

 

[Hadenough]

Refer back to #7! I had a seriously out of alignment alternator which could have been sorted in a workshop. The fabricated bracket was the problem and would have taken hours of p**ss*ng about to resolve.

 

[westernman]

You will find that the pulley on the alternator can be shimmed or have shims removed

The shim on the pulley will just move it in or out a bit?
That is not what I need - I need to twist the whole thing a bit.
Or is there something more clever?

 

[westernman]

I sawed a bit off the bracket where the alt pivots, then shimmed the other end with washers.
If the bracket bolts on to the block, then slotting the hole or re-drilling might be the way.
You can add a shim under the alt pulley to move it out.
Look for different alt pulleys.
Maybe you can file a chunk off the alt. body?
How bad is it? I think v belts can cope with being a bit out of plane?

Actually the belts seem to cope very well. Just a little black dust.

 

[Lakesailor]

- I need to twist the whole thing a bit.

Are you saying the alternator shaft and the crankshaft are not parallel? It's a bit difficult to work out what your problem is from your description.

 

[westernman]

Are you saying the alternator shaft and the crankshaft are not parallel? It's a bit difficult to work out what your problem is from your description.

The alternator itself and its shaft is not exactly parallel to the engine crankshaft. Presumably due to some wear in the bolt hole (as LadyInBed said) in the 'ear' onto which the alternator mounts.
As PaulJS said it might just be possible to get it to align up right if bolted up tight while applying some force in the right place to force it to align. Last time I changed the belt was while anchored in a gale behind Cap Bear I and just had my foot on it to tension the belt enough while I tightend it down. May be while tied up in the marina in calm conditions I can do this better.

This is a Yanmar 4JHE2 and a Balmar alternator with the original Yanmar style feet.

 

[macd]

FWIW, the sort of wear the OP describes is often promoted by improper belt adjustment: both the tensioner arm and pivot support bolts should be undone to adjust belt tension, and both re-tightened afterwards. Over the long term, failure to re-tighten the latter leads to fretting of the support lugs and hole elongation as described. The proper fix would be to bore and sleeve the affected hole(s), but that's not easily done accurately in situ.