Crossflow Noise Diagnosis

[xflow7]

In the spirit of community enrichment through sharing of experiences I figured I'd share an interesting (well, to me anyway) thing I found today.

 

 

 

NB: Probably only truly relevant for people with a Magneton alternator (as supplied by Caterham in my case)

 

 

 

Anyway, I was going to head out for a blat today, but on backing out of the garage I heard a kind of a ringing rattle sound from under the bonnet I hadn't noticed before.

 

 

 

I tried to listen around for it for a while including the screwdriver to the ear trick without much luck. Finally I noticed the alternator occasionally sounded bad with the screwdriver to it, though it was intermittant. So, I pulled the alternator out suspecting a bearing (I couldn't get the belt off without more or less taking it out anyway), but it spun freely.

 

 

 

Feeling a bit dejected at having expended the effort to remove it with no joy I contemplated putting it back in.

 

 

 

However, by chance I gave a tug on the rotor shaft and lo and behold it moved axially ~1/8" with a little groan and a rattle!

 

 

 

The long and the short of it is there is a thrust plate of some kind riveted to the inside front of the housing that apparently holds the axial position of the rotor. One of the rivet heads had popped off and another stretched so that the plate could rattle around and the rotor could float axially. I could just see the offending plate through the ventilation opennings and the broken rivet shank behind the fan on the front of the alternator.

 

 

 

Anyway, I happened to have another alternator that I'd replaced early on due to a suspected faulty voltage regulator (Caterham had just sent me a new alternator when I complained that mine had died inside of 3 months).

 

 

 

I swapped over the regulator to that one and put it in and everything appears dandy for the moment.   http://www.usa7s.com/aspnetforum/images/emoticons/hurray.gif

 

 

 

Hmmm...apologies for the length of my little novella there, but maybe it will save someone some time if they here such a noise.

 

 

 

Davexflow72006-10-07 16:21:46

[slngsht]

Man, don't you just love it when the part you need just happens to be sitting around?

 

 

[xflow7]

Man, don't you just love it when the part you need just happens to be sitting around?

 

 

 

 

I think this is the first time it's happened!

 

 

 

Only downside is that I'd already resigned myself to "needing" to buy a snazzy new lightweight alternator to replace it http://www.usa7s.com/aspnetforum/images/emoticons/biggrin5.gif until I spied the old one peering at me from over on the shelf. http://www.usa7s.com/aspnetforum/images/emoticons/blush5.gif