Last September at the Lotus Club track day I threw the fan belt
going down the back straight at PIR. By the time I got to the end
of the front straight, the temperature had climbed and I noticed it
on the gauge. At the end of the straight is not time to take a
long, hard look at the gauges. I went off into the gravel trap.
We pulled the car out and replaced the belt. The only theory we had
was that I had picked up a hunk of rubber or a rock from the track
and pulled it into the fan belt which caused it to come off and
bend one of the alternator fan blades. Ever since that off I heard
a small jangling sound whenever I braked moderately hard. I put
this down to gravel I’d picked up at the track and searched for
the elusive pebbles. During my test drive after this Sunday’s
nut and bolt check, the jangling seemed to be getting worse.
I spent most of Monday and Tuesday looking for the source of the
jangling, but I couldn’t make it happen with the car in the
garage, only under braking. Well today I had a flash, although the
wrong one. I thought the body might be touching the exhaust and
causing this sound. I stripped the nose and bonnet form the car,
started it, poked at the aluminum near the exhaust and listened. Lo
and behold I could hear the jangle, but not from the exhaust but
from the alternator.
With a track day tomorrow, I didn’t want
to try and find a new alternator in Portland! I pulled the
alternator and found two loose screws under the fan/pully that
would slide forward and touch the plates making a jangling noise! I
pulled things apart and found a nut missing. This explained the fan
belt coming off. It looks like the nut came loose, was thrown out
of the alternator, bending one of the alternator fan blades (there
is a ding on the backside) which in turn caused the belt to leave
at high speed. I replaced the nut, tightened and lock-tighted
everything and am ready for the track. It was good to find the real
reason for me loosing the belt last fall.
This post was written by
Jim – who has written 327 posts on UniBrain Trust.
Jim is the curator of UniBrain Motorsports, our resident photographer and the only one in the family to shoot a perfect 25. He enjoys eating Nadya's cooking and tries his best to stay out of her way while in the kitchen.