S/C Whine Problem...Need Help!

Hey guys,

I just spent yesterday replacing the knock sensors and harness on my 3.4 S/C and upon getting everything back together, I seem to have messed something up perhaps. I have exhausted about every resource I have at my disposal at this point.

I have taken a video of the noise and tried to get a shot of all the vacuum lines. Please let me know if anyone sees anything out of the ordinary or if you know what is wrong. I will also note that I changed the S/C oil with factory oil for it, 4 oz, while the S/C was off. The whine seems the loudest from the nose of the S/C.

http://www.youtube.com/embed/OnDwsvvNXYc

 

I have no idea, but do you have any other mods on the engine or supercharger setup? URD injectors or anything?

 

No other mods. No URD, not even an aftermarket air filter. The S/C has been on the truck since 20k miles, dealer installed, no issues until I took it apart and put it back together. Could I have done something moving it around to mess with the bearings it the nose cone?

 

arent superchargers supposed to whine? mine whines pretty loud, thought it was normal

 

That's not normal, but I think it's because the black bypass actuator is stuck open the whole time. It should be closed until you create boost, but if you look at the very end of the video it finally closes when you shut the truck off. I'm not sure what is causing that, but that might be the issue.

What RPM are you at idle? Also you replaced all the gaskets when you reinstalled right?

 

Is your vacuum around 20? Could be an air leak. Sounds like a balloon when your let the air out and pull on the sides. I don't know about the front, but sometimes the diaphragm in the actuator goes bad what if it's a small pin hole maybe?

 

This is what I am leaning towards and that's gotta be it, I just don't know what is causing it. I wasn't sure which way was closed or open. I would think that a reversed vacuum might cause it but I disconnected vacuum lines one at a time with no change.

I did replace all the gaskets, lower intake to heads, intake to S/C, and throttle body to S/C. I also replaced a couple hoses that were questionable. It must be a leak, or at least I hope it is, but I'm not sure what do to next?

It would be awesome if someone with a S/C could compare their vacuum line connections to mine in the video.

 

What do you mean vacuum around 20?

 

What's your RPM's?

 

Normal operating RPM. I can't give you a number because I'm not with the truck currently. The truck starts and runs just fine. It got to be something with the vacuums lines and that bypass valve being stuck open, and I guarantee its going to be something stupidly easy to fix.

 

Hmm, I have a 1st gen sc so my routing is different but you have the line by the actuator connected right? (Granted there is one on the black SC's).

 

Ya, you mean the hose that you can see off the bypass valve at 8 and 14-15 seconds in? That line was replaced, but never removed during the reinstall since it doesn't need removed to take the S/C off.

 

Well I'm almost positive it has to do with vacuum pressure, whether that is a leak or not. I just don't know where. The whine is because the supercharger is wide open at idle (bypass valve) and it shouldn't be. This means the pressure is wrong somewhere.

Still testing...

Idle is around 1100 RPM currently.

 

my vacuum at idle is just under 20hg. If your vacuum drops lower then 17 you prolly have a leak. Go with what rock lobster said. Blow some smoke.

 

Or some carb cleaner/wd40 around suspect lines. Rpms will go up if it makes it into the engine.

 

take off the supercharger belt - start the truck and see if it still makes the noise. mine was making a whine which sounded like it was coming from the supercharger nose but turned out to be the smooth idle pulley on the supercharger bracket as well as the other AC Idle Pulley.

 

Sorry for the lack of update. I got it fixed Saturday morning and just got back home. I ended up starting to take it apart that morning and as soon as I got to the throttle body, realized what an idiot I am.

The throttle body hadn't been torqued down...

Vacuum leak was right. Thanks for the help and suggestions everyone. I was definitely freaking out since I had to leave on Saturday.

 

It happens to the best of us sometimes. Good to hear you got it fixed.