View Full Version : Knocking/rattling Powerslot

05-29-2012, 08:16 AM
I have a 96 Prostar 190 with an LT1 and Powerslot trans. This boat is new to me and the previous owner is zero help. The noise I hear upon start and slow speeds sounds like a rod knock or a loud rattle. I did search as many threads as I could and found anything from "normal" sound from this tranny to worn damper plate. Fluid is full, red, and doesn't smell or look burnt. Shifting is smooth, and everything else seems fine, but this noise doesn't seem normal to me. It does seem to diminish with more power, but hard to tell if the engine is drowning out the sound. Anyone have any other options/opinions?

If this is a damper plate issue, I see Skidim has a 3 blade (part 1516) for $101.25 vs. a heavy duty plate (40212) for $242.64. Is the less expensive part adequate, or should I get the heavy duty plate?

Thanks for any help.


05-29-2012, 08:59 AM
Sound like damper plate to me. The less expensive part is plenty adequate.

06-03-2012, 06:27 PM
Thanks Brian, and thanks to all the helpful posts and pictures on this site, I tackled this project this weekend and here are my findings. Hopefully this will help someone else.
After removing my transmission at the bell housing, I expected to find a loose or broken spring on my damper plate. I found none, and the damper plate appeared to be in good condition. I was planning on changing anyway, but was somewhat disappointed I didn't see any evidence that would explain my rattling. I also had a new rear main engine seal on hand because I figured as long as I was in there if it was leaking, now is the time. I proceeded to unbolt the ring gear when I noticed some metal pieces in the bilge right below the ring gear. They looked like some kind of sleeve, and all the pieces weren't there. As I unbolted the ring gear, the bolts progressively got harder to turn.
After removing all 6 bolts, I discovered the threads right under the bolt head to be damaged on all 6. I then discovered the source of the metal pieces, a dowel,alignment pin on the crankshaft flange had sheared, and the missing piece was still inside the hole. Now the bolt damage made sense, as the ring gear must have shifted just enough to damage the bolt threads and make the ring gear not spin round with the crank.. The pieces of the dowel pin were rattling around in the bottom of the belhousing as well. I purchased a new dowel from the Chevy dealer, and new ring gear bolts from twin city auto, torqued the bolts, installed my new damper, put the transmission back on, and followed the engine and shaft alignment procedure from this site. I found my alignment to be off, and both rear trunion locking bolts completely loose. Got everything lined up, and went for a test drive today. Everything is quiet, and runs perfect. No more rock mixer in the rear on my boat.

Those rear engine adjuster locking nuts are a bear to get at, anyone know what size nut they are?
Looks like I need a crow foot wrench to get in there.

Thanks Team-talk, I wouldn't have been able to complete this job without this site

06-03-2012, 07:13 PM

06-03-2012, 09:51 PM
Glad you were able to get it fixed.