My alternator belt kept loosening; I re-tensioned it and re-torqued the fixing nut but the problem recurred. After looking at this, I found that the M8x1.25mm nut has serrations on the back that lock it tight, preventing slipping. Mine were seriously worn. Bought some new stainless nuts on EBay ($9 for a bag of 25) and problem solved. Apparently these take only a limited number of re-torques before wearing down and my 745 is 29 years old, so it was time.

Serrated Hex Flange Nuts: https://www.ebay.com/itm/25-M8x1-25-Metric-JIS-Serrated-Hex-Flange-Nuts-Class-10-J-I-S-B1190-12mm-Hex/151141682143?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Thank you!

Just yesterday I heard the telltale screech and became concerned, as I'd just changed the coolant pump two months ago, so fairly sure the alt belts (a 240 of course) were new and adjusted. On arriving home, I found the fixing nut was indeed loose. Scratched my head, considered but didn't use threadlocker, readjusted and tightened it, making note of it in the little book. Could I be forgetful?

I'll put one of these (more rust-prone than your SS suggestion) on later today and check back in a couple months.



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Art Benstein near Baltimore

Why didn't Noah swat those two mosquitoes?

Steve, good advice and good to hear from you.

For those new to the BB, Steve is responsible for compiling the 700/900 FAQ over the course of many years.
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Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)