Yanmar alternator pivot bush replacement

[IanCC]

Hi,
My stock hitachi alternator on my 3gm30f seems to be missing bushes. It's hole sizes are approx 9.5mm for m8 bolts. If someone could tell me how to fix this i would very much appreciate it.
Also the hole the bolt slides through, in the water pump(?), seems a bit sloppy so it's difficult to align pulleys radially. Is this normal? Or can i get it sleeved?
Thanks in advance for all and any input.
Ian

 

[rotrax]

Not sure what you mean by 'radially'.

The hole diameter size sounds iffy, but as long as the alternators swivelling hole/sliding bush - if, indeed, it has a sliding bush - is pulled into firm contact with the machined face it sits on by tightening the long bolt, any pulley mis alignment can be checked easily with a straight edge.

A picture might help.

 

[IanCC]

Not sure what you mean by 'radially'.

The hole diameter size sounds iffy, but as long as the alternators swivelling hole/sliding bush - if, indeed, it has a sliding bush - is pulled into firm contact with the machined face it sits on by tightening the long bolt, any pulley mis alignment can be checked easily with a straight edge.

A picture might help.

Thanks for reply.

Boat is 3 weeks away unfortunately.

I can align, with a straight edge, one edge of the pulley. But the other side of the pulley is not in the same plane. Partly due to a little sloppiness in the mounting bolt hole in the engine/water pump but mainly due to the oversized holes in the alternator. Obviously as the belt is tightened the alternator twists because it doesn't have the correct hole size anymore.

Personally i think it's knackered. How anyone thought it was a good idea to remove the bushes from the alternator is beyond me.

 

[VicS]

Hi,
My stock hitachi alternator on my 3gm30f seems to be missing bushes. It's hole sizes are approx 9.5mm for m8 bolts. If someone could tell me how to fix this i would very much appreciate it.
Also the hole the bolt slides through, in the water pump(?), seems a bit sloppy so it's difficult to align pulleys radially. Is this normal? Or can i get it sleeved?
Thanks in advance for all and any input.
Ian

A picture always helps
You are saying that bolt #5 is a loose fit in the alternator mounting lugs and also in the water pump mounting / thermostat housing?

 

[rogerthebodger]

The rear alternator mounting on my old boat has a bush in the mounting that a bolt fits through . The front one does not.

It looks to me like a simple tube that the bolt pases through which looks like its designed to allow the alternator to expand and contract with heat.

A local engineering works could make one being 9.5 mm O/D and 8 mm I/D with a length say twice as long as the mounting thickness

Similar to this

 

[IanCC]

A picture always helps
You are saying that bolt #5 is a loose fit in the alternator mounting lugs and also in the water pump mounting / thermostat housing?

View attachment 167992

Correct, thanks for response. Much more so in the alternator than the housing. In the housing it wiggles which means i can't get things properly aligned.

 

[IanCC]

The rear alternator mounting on my old boat has a bush in the mounting that a bolt fits through . The front one does not.

It looks to me like a simple tube that the bolt pases through which looks like its designed to allow the alternator to expand and contract with heat.

A local engineering works could make one being 9.5 mm O/D and 8 mm I/D with a length say twice as long as the mounting thickness

Similar to this

View attachment 167995

Thanks for input. I think it is perhaps a bit more complex as the holes are now no longer circular. I think £40 on a second hand recon alternator is the right answer re the alternator.

 

[rogerthebodger]

If the hole is now not round I would open it up to a larger size and fit a bigger diameter tube ito the hole to reduce it to 8 mm I/D

 

[IanCC]

If the hole is now not round I would open it up to a larger size and fit a bigger diameter tube ito the hole to reduce it to 8 mm I/D

Mmm but how do you make sure you are drilling both ends inline with each other and parallel to the axis of the alternator? I am not an engineer. Thanks for input.

 

[rogerthebodger]

With a long drill that will pass through one pivot trough into the next in one go

Even drilling by hand with a long drill will keep things aligned

 

[IanCC]

With a long drill that will pass through one pivot trough into the next in one go

Even drilling by hand with a long drill will keep things aligned

If one hole is ovalled one way and the other the other way, which is likely, i don't think my skills are up to drilling it straight.

 

[rogerthebodger]

If one hole is ovalled one way and the other the other way, which is likely, i don't think my skills are up to drilling it straight.

Don't forget you will be fitting a sleeve in the enlarged hole anyway

but if the alternative is buying a new alternator if you get it wrong there is no downside and if you get it right you have a nes skill and saved the cost of a replacement alternator

 

[IanCC]

Don't forget you will be fitting a sleeve in the enlarged hole anyway

but if the alternative is buying a new alternator if you get it wrong there is no downside and if you get it right you have a nes skill and saved the cost of a replacement alternator

Thanks, i am sure you are right, but i havecdone enough drilling and know that is beyond me. At least when £40 gets me a replacement.

I think the other bit, needs taking to an engineering shop to drill and sleeve. Nearly £400 for a replacement.

 

[Boater Sam]

Its only aluminium. If you file the holes on the opposite side to which they have worn and then drill them larger, they should come out in line.
Drill out to a size that you can get thick walled steel tubing with and 8mm clearance bore size and the same OD as the drill.
Slop in the water pump casting should not be a problem, I doubt that it has worn oval.

 

[IanCC]

Its only aluminium. If you file the holes on the opposite side to which they have worn and then drill them larger, they should come out in line.
Drill out to a size that you can get thick walled steel tubing with and 8mm clearance bore size and the same OD as the drill.
Slop in the water pump casting should not be a problem, I doubt that it has worn oval.

Thanks for response. Yes probably right. But got to find and buy a long drill and steel tubing. Then buy an aluminium file and something to clean it. Plus my time when there is a zillion other things to do and i am not convinced i could do it. Or, chuck £40 on the table and that problem goes away.