When I first installed it just the other day, I found that even with the alternator bracket tensioning tool, I couldn't get the 7400 belt tight enough. We'd been using the 7400 successfully for many years before this "exercise." The 7390 belt was too tight, and I couldn't even get it on the pulleys.
It seemed like we had no choice. I could have had Metal Magic make the slit on the bracket at the top part longer, but that would have left almost NO metal underneath the the bracket.
On the way home from the boat, I had another thought. What if there was a belt size between the 7400 and the 7390?
Do they make a 7395?
YUP!!!
$16 for a true NAPA heavy duty belt, and a day later, everything is working just fine.
Here's what I learned: A long belt works if the slit at top of the alternator bracket is long enough to get the alternator WAY out (the 7400, worked for us for four years). The alternator HITS the engine block if your belt is too short (the 7390). The middle sized 7395 works. The alternator adjustment arm doesn't adjust a whole lot!
I'll purchase a backup 7395 tomorrow.
I also made note of this on the C34 Tech wiki.
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Topic: Alternator Bracket Failure - Check Engine When Running (Read 9562 times)