ok so i took the bypass valve out and i noticed it does not seem to close all the way. there is a ring of light around the butterfly valve, so i tried to back out the set screw and its backed all the way out and there is still light comin through...is that normalÉ could that be the problem with my boost lostÉ should it shut and seal tigt
cheers

 

You should be able to seat the butterfly. If it won't close, you're losing power and boost. Call Detroit Tuned (or us) and get yourself an DT BPV. If you are leaking boost from a faulty BPV, you'll notice a large power gain.

 

sound like your spring is broken. A replacement is in order, it's not an expensive part. Stock will work, the DT closes sooner, and has a more abrumpt transition from open to closed.

Matt

 

I have very low mileage (under 25k) bypass valve in perfect condition if you are interested.

 

how much do you want for it?
will you take paypal and does it close all the way?

 

I just had to replace mine. It's not an expensive part.

 

well i changed the bypass with a new one..what a waste of money...now i am stumped

 

It is very common that the butterfly valve is mis-aligned. You could try to re- align and center the butterfly valve by loosening the screws holding it on the shaft until it closes properly. If your stock spring is in good condition you should be good to go. Be careful when setting the stop screw so that the valve just shuts and does not stick closed.
Steve

 

the bypass is good......anyone hear or seen a wore out sc? will it make weird noises or anything??

 

are the rear water pump gears going, and the coatings on the rotors going. There's lots of info on both here. Spend some time searching. BTW, the gears going makes noise, the coatings going doesn't.

Matt

 

Recently installed a boost gauge in my '02 MCS and found I am only making ~8# of boost. Only owned the car for 7 months but have 5 years of maintenance records from previous owner. No record of the BPV being replaced. I have replaced the supercharger belt (was due) to make sure it wasn't slipping, no change in max boost. Tensioner looks fine, lots of tension and ~1/2 a hole shows on the tensioner with the new belt. Car runs great, smooth, quiet and no belt noise, but I suspect I am loosing considerable horsepower. I plan to check out the BPV but before I take it apart I would like to know if this is strictly a replacement part only or can you buy a BPV rebuild kit and save yourself a little cash.


'02 Liquid Yellow MCS