Alternator shaft sheared off - possible cause?

[KevH]

Long time no post...been busy.

Anyway, tootling down the M6 this week at a steady 60, red generator light comes on so I turn off the ignition and coast to the hard shoulder. It is, of course, p***ing down with rain.

I open the lid to find that the alternator shaft has sheared at the point where it enters the main body, right between the two pulley halves.

Any thoughts on what the cause might have been? The belt tension seemed OK before the trip.

The engine was upgraded to 1776 from 1600 in April, but I kept the original alternator. Is that a possible factor? Anybody?

 

[ozziedog]

When you get the thing out, just have a good look at the bearings and where they`re housed, have a look for signs of heat and stress. You`d expect a fan belt or two to go before that happens wouldn`t you. Got the right sized pulley on there have you ? Does it still spin ? Might be worth shoving your phone in the fan housing and taking fifty photos to have a good look round as well.

Ozziedog,,,,,,,,,,,,,,,Might just be a shit alternator shaft ,,, hopefully :mrgreen:

 

[Peter Good]

Possibles: -
Out of balance alternator rotor
Bent / damaged alternator shaft
Top / Bottom pulley not in line
Top Pulley set up / adjustment
Damaged pulley
As ozziedog suggests photo's will help...
Peter Good

 

[mike202]

sorry to hear about that, the alternator or generator throwing the belt off and breaking seems to be a recurring issue. There was a thread recently about the pulley wheel shattering on someones engine. I had a similar problem when the belt came off for no apparent reason,it was not broken, but the nut holding the pulley wheel halves on the generator came loose. I replaced the generator with a new bosch alternator, and I have had no problems since. (about 3 years I think) I believe the bearings had worn on the old generator was the cause.

Interesting about the 1776 upgrade, did you go for a new engine or a rebuilt one, and does it drive a lot better now?

 

[mike202]

this thread
http://forum.earlybay.com/viewtopic.php?f=4&t=74054

 

[KevH]

Might just be a shit alternator shaft ,,, hopefully :mrgreen:

Cheers Oz.
I am having the engine dropped this coming week and having a good look around the fan housing, as suggested. I have had good feel around already and all seems well back there, ie there is no play, the fan and alternator rotate smoothly, no obvious causes of tension of blockage. But will look closer once access is easier.

The alternator was on the bus when I bought it in 2011, so I don't know its history. Maybe it is just tired...I know the feeling.

Not sure which replacement to buy, I have been reliably told that they are all basically the same, which doesn't inspire confidence in them, but will probably go with a higher output.

Kev

 

[KevH]

Possibles: -
Out of balance alternator rotor
Bent / damaged alternator shaft
Top / Bottom pulley not in line
Top Pulley set up / adjustment
Damaged pulley
As ozziedog suggests photo's will help...
Peter Good

Cheers Peter
All seems Ok although I will double check, and have somebody else check too, the alignment, just in case. It seems an incredible coincidence to have gone so soon after the engine swap.

Kev

 

[KevH]

sorry to hear about that, the alternator or generator throwing the belt off and breaking seems to be a recurring issue.

Interesting about the 1776 upgrade, did you go for a new engine or a rebuilt one, and does it drive a lot better now?

Hi Mike
Yes, I can recall StuF having an exploding pulley a while back, and speaking to one or two since, that seems a relatively common problem. But even the guys who look after my bus for me (and they really know their stuff) are mystified at a sheared shaft. Maybe it was just tired, but I'll ask them to double check the alignment with the new motor.

The 1776 is a straightforward refurbished block with new crankshaft, etc. supplied by TEC. I chose to have the existing peripherals such as carbs, etc. transferred over as they are less than 6 years old, and (sadly) kept the alternator too.

I've been getting slightly lower mpg which I put down to running in, but the slight increase in torque is a godsend for the hills and gives an extra 5mph cruising speed on the motorway, allowing the occasional venture out of the first lane (whoopee).

I have spent a whack this winter, with a front disk upgrade and new loom, plus the engine, so I was really hacked off when the red light light came on. I would heartily recommend a brake and loom upgrade if you haven't done so yet.

Hope all is well in Monty land.

Kev