Stimey131

I had my P1SC upgraded to a D1SC with helical gears, all new bearings and seals. Got it back and installed it and did a test drive with a couple of pulls up to about 4k rpm. I stop because it needed top Dyno tuned. On the Dyno he made about 4 pulls with no problems. Then on the 5th pulled the supercharger started to make this horrible chattering sound especially on deceleration. It sounded like an output(impeller) shaft bearing, so I order a set of output shaft bearings and a new seal. I got the new bearings and seal installed. I reinstalled the supercharger today, started the engine and got the exact same noise. Now I'm at a complete loss as to what the problem is or how to fix it. Any Help would be greatly appreciated.

Stimey131

Today I contacted superchargerrebuild.com by email add that's the only way to communicate with them. They suggested I try using some 20w50 motor oil. I was reluctant, but since nothing is working why not. I drained it and filled with 20w50. When I started the engine is was quiet and smooth, but as soon as I just slightly revved the engine the chattering sound came back. Although it was about 40% quieter than before it was still very loud. I also noticed addy low rpm (idle) the chattering sound coincided with the lope of my cam. This makes me think there is some sort of bad tolerance issue in the bearings. My problem with that is that it was completely rebuilt less than 100 miles ago and then another set of output shaft bearings just this past week.
Any thoughts about this. I'm not sure what to even do next. I can't just keep ordering bearings until I hopefully get a good one.

neutron82

who rebuilt it the first time?... I would have went back to whoever did it as soon as I heard the noise... you might have screwed yourself by trying to rebuild it the second time on your own and then adding different oil

Stimey131

It was supercharger rebuilds. I had them do the rebuild and upgrade to a D1SC because my P1SC needed to be machined out where the bigger impeller was going. They're actually very easy to rebuild. They do not offer any type of warranty, but they are still working with me trying to get right. They are the ones that suggested I try the 20w50.
I had a guy tell me it is probably gear lash, but it never made this sound before, although it does have the helical gears now.
I'm going to make a short video of the sound and see if I can figure how to post it up.

Stimey131

I couldn't believe what causing this noise. It was a malfuctiining BOV. I originally ruled it out because I just installed a brand new one. I had first installed a used one and thought it might be causing the problem, so when I put brand new one on. I figured it had to be something else. I got 2 bad BOV in a row that were not opening to release the back pressure, causing the SC the make the noise. I finally borrowed a known good working BOV installed it and the sound disappeared. So I drained out the 20w50 oil and refilled it with procharger SC oil. All is good with the engine now. Now I've got to work on better traction. Thanks for all your help guys.

PEETYZ

Wow did not expect that. Glad you got it fixed. You need to make sure the correct psi spring is in the blow off valve. If its too high it wont function properly with the lower psi of the blower.

Josh@AandASuperchargers

What brand were the 2 defective BOVs?

Glad you figured that one out. I've seen too many horror stories after headunits rebuilds are done by anyone other than the manufacturers.