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914World.com _ 914World Garage _ problemswith the fan belt

Posted by: bernbomb914 Jul 28 2005, 08:32 PM

I am having trouble keeping my fan belt on. It comes off as soon as you rev the engine. The alignment looks as good as my old engine. You cant move the alt back any furtheras there is no room. What am I missing here What majic wand do I have to have to cure it.

Bernie

Posted by: bd1308 Jul 28 2005, 08:40 PM

new belt.

Posted by: bernbomb914 Jul 28 2005, 08:42 PM

how about 3 new belts.

Posted by: ! Jul 28 2005, 08:49 PM

Pulley, shims and/or tension...

Posted by: JOHNMAN Jul 28 2005, 11:19 PM

I will just assume that we are talking 914-4.

The last time I saw this happen, we found that somebody had put the alternator pully on BACKWARDS. The notches should face away from the alternator body. This was enough of a misalignment that it caused the belt to jump off as soon as the engine speed was increased much above idle.

We checked all the alternator bolts and found them all tight and finally took a peek at the pully itself.

Good luck.

Posted by: tesserra Jul 28 2005, 11:26 PM

Johnman beat me to it. I drove me crazy and on top of that it was on a smogged '76, so I had to deal with the smog pump bracket/[pulley.
Did not realize the pulley was on backwards until the motor was out for some oil leak work. DAPO

Posted by: Jake Raby Jul 28 2005, 11:27 PM

Alignment...

Do you have two yardsticks????

If so you can use them to place in each belt groove at the top and bottom and adjust the alignment so the two touch when the alignment is correct...

Its kinda tough in the car due to space limitations- we do it on the dyno on every engine that gets a DTM or stock sheetmetal...

Took one to 7,800 today running the belt and she hasn't popped off yet..

The yardsticks work well, you cannot "Eyeball" these adjustments.

Posted by: bernbomb914 Jul 29 2005, 09:56 AM

if I put the pully on like you say it locks up. is there a shim kit for this to move it away from the alt. or should I try wshers?

bernie

Posted by: Jake Raby Jul 29 2005, 09:59 AM

The entire alternator moves to correct the adjustment. The bracket that holds the alternator to the shroud has elongated holes and two 13mm bolts. Loosen them and move the alternator fore and aft till proper geometry is achieved.

Posted by: bernbomb914 Jul 29 2005, 10:04 AM

been there done that

Bernie

Posted by: john rogers Jul 29 2005, 10:45 AM

If it were me, I'd check the fore/aft alignment between the two pulleys with a steel straight edge. Then I would use a dial indicator and check each pulley at the outer edge for both radial and axial trueness. Then I'd check the alt shaft end play and check the crank end play. Last of all is the belt the right type and the edges of the belt sitting against the V of the pulleys as it should? Good luck.