When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
belt hitting pulley - because alternator brkt crked?
I thought others have posted about this problem, but couldn't find any threads when I did a search.
I noticed a noise yesterday that I was able to track down to the belt hitting the crankcase pulley.
To be more specific:
at certain rpms (generally 3000-4000 rpm), the part of the belt that comes off the SC pulley on the alternator side will hit the crank pulley. With the engine running and looking at the engine, when I give it gas, in that specific rpm range the belt will deflect enough (I hope the crank pulley isn't deflecting ) to hit the pulley. When that happens, the belt starts bouncing back and forth, hitting the pulley until you get out of the rpm range and it settles down.
While looking around in there, I noticed that the SC bracket on the alternator side is cracked. Now I am wondering if the crack is allowing enough movement to cause the belt to hit.
Hey John,
Let me try to understand visually.
Are you talking about the supercharger belt running close to the waterpump pulley like the one below?
Click to see the full size.
I thought that was the crank pulley. Anyway, have you had any problems with this? I am hoping that it is doing this because of the cracked bracket.
I know for a fact this bracket was OK a couple of thousand miles ago, because the mechanic that did the clutch TSB had this bracket off and didn't say anything about a crack. This guy would have definitely noticed anything wrong, so it must have happened in the last couple of weeks and just started making a noticeable noise the last few days.
Oh then, yes I had some major issue with the problem you were having.
Upon first installation, I immediately noticed how the belt ran so close to the water pump pulley and it made me feel very uncomfortable. Gregg test drove my car and pointed out some sort of rubbing noise on certain rpms 4-5K.
When the smaller pulley 3.8 and later 3.4 inch pulley was installed the problem was no longer there with the noise.
My vibration(harmonic?) is particularly present only on exactly 5K rpm and nowhere else now.
With smaller pulley the distance was much better between waterpump pulley.
I asked Comptech and this board about this but they weren't much helpful.
I would think trying anything smaller than the stock current supercharger pulley will solve your problem along with some hp/tq increase without raising the intake temperature too much.
Good luck John and hope the new pulley will solve your problem.
By the way my orginal bracket is still doing well without any cracks but who knows when mine will start to go?
Like I said noticeable vibration exist only when I stay at 5K rpm and start to disappear if I get past that rpm range, it is strange.
you don't happen to have a copy of that file do you? The link in the other thread no longer works (at least not when I click on it directly; I will try a cut and paste to see if it works that way).
Since this just started happening and I just noticed the cracked bracket, I am hoping they are related and the problem will go away once the bracket is replaced.
I looked at the bracket more carefully and it is definitely cracked all the way thru.
I know for a fact this bracket was OK a couple of thousand miles ago, because the mechanic that did the clutch TSB had this bracket off and didn't say anything about a crack.
05-12-2002, 10:29 AM
belt hitting pulley - because alternator brkt crked?
) to hit the pulley. When that happens, the belt starts bouncing back and forth, hitting the pulley until you get out of the rpm range and it settles down.
