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im an idiot, HELP


NAXJA Forum User
west IL
alright i put a new alternator on about a month ago. I just tore my belt to peices last night from it hitting the fan. i go to put a new belt on and the pulley on the alternator is to small, the reason hit the fan. I took my old alternator back and its been sent out already and no one can get a pulley. local junk yards dont have anything. can anyone give me a hand here? I need it ASAP. thanks a lot guys
If the diameter is too small on the pulley, that maybe a good thing, it will cause the alternator to turn faster which will increase the output at idle, you may just need a shorter belt.

If the pulley is too small by not having enough grooves then go back to the place you got it and have a fit until they fix it, the pulley of some late model dodge cars and trucks may also fit even if the alternator won't. any respectable parts house should have checked the alternator over and made sure that both where the same. If it is the wrong alternator im suprised you got it to bolt up.

If you really want to have fun do a search on here about the 170 amp alternator from a durango i think. if you can find the exact application the you can tell the parts guys that the 170 amp unit will work and has the right pulley size. then make them give it to you at the same price cause they screwed up in the first place.

Just to make sure you don't have trouble again, you may wnat to check the part number on your belt. Problem is, most XJ belts I've seen have six ribs, not four or five - and you'll want to be certain of that before you go too far.

For 87-90XJ, you'll have a Delco alternator and pretty much any six-rib GM pully will work fine (they're a pretty standard size in production - I just don't recall the pully OD offhand.) For later XJ (Mitsubishi alt? Don't remember, and don't have one handy...) it's probably going to be a six-rib MOPAR pully. The difference is probably the diameter of the shaft it mounts on - but I could be wrong.

Either way, check the belt first - look for "K-some number." K4 is a four-rib, K5 has five ribs, and K6 is the six-rib I'd expect to see. The rest of the number gives the length of the belt - I could probably tell you what that is if you post the number (they're not that hard to read - just need a little practise. Even decoding the V-belt part numbers isn't that hard - there's a two-didig that's usually between 11 and 21 (the belt top width) and a three digit that gives the belt length (typically to within a half-inch.))

There are times when all that time I wasted behind the parts counter comes in handy...