Stumped by rattle. Any ideas?

[m3f_mangle]

First, videos:


http://youtu.be/CeOI4RHReWc


http://youtu.be/2PhbYtJjETY


http://youtu.be/asn66eaWrEc


It doesn't start until the car is warmed up. It seems to happen any time load is changed on the engine (light accel, decel, shifting). It seems to have developed a little bit of a squeal along with it, leading me to believe it's a pulley.


The car has a set of evosport pulleys and what appears to be a rebuilt alternator. The engine/accessories seem to be otherwise stock.


The aux fan had seized. I replaced it this morning. It didn't affect the sound at all.


I need to find a 32mm wrench and water pump holder to pull the fan and belts and start checking things.


Until then, any ideas?

[m3f_englishtom1596q]

sounds like a metal ball bearing rattling around in the pulley.. id pull the belts and spin them by hand and see if something has gotten trapped or fallen loose behind those nice pulleys.

[m3f_desertdriver]

OP, what did you find to be the cause of that noise?


I have a 95 and it started making that noise too, although it makes the noise (a tinny sound, almost like a thick pan lid bouncing around when boiling water) from low speeds up to about 50-60 mph.


It also seems correlated to a low frequency throb that gets noticeable around 50 mph, and loud around 75 mph.


This just started yesterday.

[m3f_cracky]

definitely a pulley and/or the alternator rotors contacting the coil(ie: bad bearing)

[m3f_mangle]

I did figure it out. First, the squeal was the tensioner pulley on the AC belt.


The rattle was much tougher. It turns out that the previous owner mixed and matched a set of underdrive pulleys. He had the evosport pulleys on the water pump and alternator, but a turner pulley on the power steering pump. He had used the serpentine belt from the evosport kit, which was too small. I figured this out when I pulled the belt off.... It was really difficult as the tensioner was maxed out.


The undersized belt was pulling the tensioner pulley bolt in to the harmonic balancer, making that awful noise when things were warmed up. Once it cooled a little, the noise went away. A longer, non-stock size belt solved all.

[m3f_englishtom1596q]

score!