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Alternator Issue
Daddylonglegs - 19/8/12 at 08:18 PM

First of all I will apologise for the life story, but it helps to understand the problem.

As per a previous thread I have suspected my alternator may be in need of some TLC. Although the charging seems to be OK according to the voltages and comments on here, I still have the issue with the charging light not going out until I get the revs over 1500 then it stays out even on tickover. I can live with that, but tonight me and the boss went out for a nice run to a pub about 25 miles up the road.

The car behaved well and all was fine until we came to leave. The car started straight away, the charging light was on as usual, but the belt was squeeling like a stuck pig! I thought it may be a slipping belt and blipped the throttle to get the light to go out as normal but it did not. I did it again but still no charging and lots of squeeling. Then I smelled the rubber and saw the smoke coming out from the air filter hole in the bonnet

Stopped the car, lifted the bonnet expecting to see the belt on the floor, but it was fine. However, the alternator was VERY hot and I could not turn it by hand. I used a screwdriver to try and free it off, which it did. I started the car and it was fine. Blipped the throttle and the light went out, volts to 14V and there was no squeeling.

So I guess the belt was trying to turn the alternator but couldn't hence the racket, and no charge.

My assumption is that the alternator bearings are probably on the way out hence the heat and temporary seizure of the shaft?

Any help/advice is gratefully received chaps & chapesses

John


maccmike - 19/8/12 at 08:23 PM

Yeah I think I would go with your diagnosis.
Get it off and strip it, if its bearings, new alty, sorted.
If its overheated and seized, you'll have to look for a fault else where, +new alty.


rusty nuts - 19/8/12 at 08:30 PM

If your alternator is close to a source of heat fit a heat shield, alternators do not like excessive heat


britishtrident - 20/8/12 at 07:47 AM

If bearings are gone not worth the effort of repairing pick up another alternator.
If a second-hand rather than rebuilt unit put new brushes in before you fit it. You could also fit a new regulator.

Bearing failure was probably caused by gross over tightening of the drive belt sometime in the units past history.

[Edited on 20/8/12 by britishtrident]


RichardK - 20/8/12 at 11:21 AM

Yeh, as above not worth the bother in repairing,just get a new one and fit the belt to the correct tension and watch all your charging problems go away

Cheers

Rich


Daddylonglegs - 20/8/12 at 09:06 PM

Took the alternator off this afternoon and it sounds like the rear bearings are foobarred. There is no play in the front ones, but if you rock the cooling fan you can feel a little movement at the tail end, and spinning it gives a rough sound so I'm going to source another one.