For those who like to troubleshoot...

[shippman]

Here's a problem I have been working on for several months now. I found the culprit this past weekend, but thought some of you might like to take a stab at it.

Background: '82 C20, 350 SBC, NV4500 5spd trans. Several months ago I installed new GM Performance L31 with serpentine belt setup. I used the 91 TBI setup that was on the old engine but on a new vortec TBI manifold. I also replaced the mechanical clutch setup with a hydraulic clutch setup from a 85-87. The new engine required a new flywheel but I used the same pilot bearing, pressure plate, and clutch disk that was in the 82 because they only had about 5K miles on them. I did replace throw-out bearing.

OK, to the problem... After everything was installed again it was out for a test spin. The new clutch setup worked very well. Engine ran well and I was very pleased for the first 15 minutes or so. Then a loud squeal began from under the truck. It was localized to the bell housing area. I used a probe to try and isolate the noise... it was definitely in the bell housing.

Since the pilot bearing was real sloppy in the crankshaft, I removed the trans and clutch assembly and replaced the pilot bearing. After reassembly and 15 minutes into the test drive the noise reappeared.

Now it is your turn... what you think? Ask any questions you have... let's see if you come up with the same culprit I did.

Mike