I had this problem for a while, it drove me nuts. Your alternator on the m42 has a bushing that surrounds the bolt that holds the alternator. The alternator uses a "tensioner" with a nut and bracket to tension the belt onto the pulley. Over time the bushing, and usually either the nut or the bracket wear down and will cause this problem and will no longer properly tension the belt, and will change the angle of the belt on the pulley. The way to eliminate this problem is to replace the "alternator bracket bushing." Most likely your nut will be stripped, it has teeth but they are prone to wear, so I would recommend buying a new "alternator idler nut." If you need to, buy another "alternator adjusting bar" as well, they're pretty cheap and come in black and look pretty clean. Replace your belt also if it's old. Good luck, it's not too hard of a job.
I had this problem for a while, it drove me nuts. Your alternator on the m42 has a bushing that surrounds the bolt that holds the alternator. The alternator uses a "tensioner" with a nut and bracket to tension the belt onto the pulley. Over time the bushing, and usually either the nut or the bracket wear down and will cause this problem and will no longer properly tension the belt, and will change the angle of the belt on the pulley. The way to eliminate this problem is to replace the "alternator bracket bushing." Most likely your nut will be stripped, it has teeth but they are prone to wear, so I would recommend buying a new "alternator idler nut." If you need to, buy another "alternator adjusting bar" as well, they're pretty cheap and come in black and look pretty clean. Replace your belt also if it's old. Good luck, it's not too hard of a job.
I did tightened that very same bolt slightly and it stopped the squealing completely. As you say it does need replacing as the bolt is curved up.
I’ve got the same problem but I think I may have to big of a belt, I’ll try tightening it but it didn’t do much the last time I tried it
iv just started my 325 1987 up and its squeaking on rev hopefully same problem and i can fix it
Tighten the nut. Will stop straight away.
@@akilleez84 which nut
@@dalynferguson2582 big 20mm I think, linked to a bar with teeth, near the top right, near pulleys, slightly adjust only