Hey, so i bought a new alternator, and installed it. from the previus post someone said "to re-tension the belt, use a small length of wood or a large screwdriver or something to pry up on the alte. while you tighten the lock bolt." but how much do i pry up? the belt has a little play right now after i just installed it. i started it, and the idle is at 2k constant? is this normal? the battery was dead prior.

 

The idle will have nothing to do with the belt.

**** I pry up with a very large screw driver about 3 foot long about as hard as I can with one hand. Just enough slack that the middle of the belt wobles some with my hand.

Search on idle adjustments and so on.

 

In the 87FSM there is a section called SCHEDULED MAINTENANCE SERVICES. I suppose the other FSM have something similar.

There you will find how MAZDA thinks the belt should be tightened. Their test has you depress a section of the belt using 10kg (22lb) and measure the deflection which should be 14-17 mm (0.55-0.67).

That said, I've never done that method. I use a big screwdriver and tension til I think it's where it ought to be.

2000 rpm and idle? Warmed up engine? Man, that's high. Also not much related to checking a drive belt.

 

When I first install the belt, I tighten it pretty much as far as it will go because belts stretch a bit. I don't think your really gonna over-tighten it ust by using the pry-bar method.

 

ok so i started up my car and the idle is at 2k, the belt seems like where it should be, maybe a little bit less? i tried moving the car around my driveway, 30 seconds of lightly gasing, the car dies. this was on a dead battery? what would be my problem here?

 

?? anyone

 

It's nothing to do with the alternator belt tension.

A dying battery won't run the car long. The fuel pump and the ECU eat amps pretty quick.

A cold engine is supposed to idle a bit high until it warms up. A little high means around 1200 rpm and gradually go down to 750rpm or so after maybe fifteen minutes or so of running.

We guess your saying you can't get the battery to stay charged. Is the small electrical plug attached to the back of the alternator?

If so, then you NEED to get a digital meter and check the output of the alternator while it is running. It should be somewhere in the 13.5 to 14.5 vdc range while idling.

You can't be helped unless you do some checking like I just described. UNLESS you have tons of spare cash........then start replacing things at random. That'll qualify you as a airforce avionics technician. humor directed at AF personel.

 

Oops, I did, and evidently it may have locked up the bearing as I pulled over with the belt smoking. I remember thinking, my cdi will run on like 5 volts to get to autozone if I have to. I went up the hill to autozone, pulled off rubber chunks and put on the new belt.