Alternator belt squeal

Skifledanabit · December 16, 2008, 07:26:24 PM

ok, this one isnt my car... but he needs help anyway...

FC3S 1990, his alt belt snapped a while back, I managed to find one in the boot of my car (thanks Matt) and headed over to help him out, got it changed on the roadside and since then he\'s had rediculous squeal when stationary, he loosened the belt off and tightened it up and tried all sorts of combos.

Anyway... it only seems to squeal with the lights on, and when they are turned on, the belt visibly slackens...

Come on guys, need ideas here, cheers!

rx7pat · December 16, 2008, 09:08:34 PM

Hello mate to check the tention of the belt you have to measure from the center of the pulley to the center of the other pulley for that belt. depending on the length for a 7 to 11 inch distance it should deflect about 1/4 inch of movement. 12 to 16 inch distance the belt should deflect 1/2 inch. other than that it could be the bearing on the altenator. hope it helps

m1tch · December 16, 2008, 10:20:36 PM

I also have this problem, but has been partly cured when prof tightened it up for me a bit, but it might be the alternator bearing as said above, mine squeels when there is extra load put on the alternator when lights and stuff are put on

David Nock (RIP) · December 17, 2008, 09:01:01 PM

Worn V belt profile likely - the belt bottoms on the pulley and slips under load because there\'s no grip to the sides of the v. Try a new belt.

kev-yorks · December 18, 2008, 12:39:48 AM

Like tyres belts go hard with age and need changing, but a spray with belt dressing can prolong there life. Don\'t just over tighten as all you\'ll achieve is premature wear on the pulley bearings.

Skifledanabit · December 18, 2008, 03:21:47 PM

It is a brand new belt, two brand new belts in fact, the 1st new one snapped again

David Nock (RIP) · December 18, 2008, 05:11:45 PM

Something wrong with the mechanical load then? Alternator bearings as above, or - what else does the belt drive? Water Pump?

Skifledanabit · December 19, 2008, 01:52:30 AM

as far as I\'m aware, its a standalone belt

pdtaylor18 · December 19, 2008, 05:52:35 PM

Couple of things cause this. When you tighten a belt then you must rotate the crank and re-check the tension, do this a few times and you would be surprised at how slack it can be in places and not others when rotated round a bit. If you have any play in the bearing of the pulley tensioner or other ancillary then doing this procedure can help.
If this has been slipping for a while then the pulley itself will become highly polished and it will pay to take the belt off and rough the metal up a bit with sandpaper and that should provide a good key for it. Sounds silly but make sure that the belt is the right profile for the pulley and that as much belt is in contact with the pulley as possible.