Capristo bypass valve

To correct the buzzing on my oem bypass valve, I had to perform both of the following:

Step 1: Increase the pre-load tension on the bypass actuator rod (rotate counter-clockwise to lengthen).
Possible fix for a noisy/rattling 355 exhaust valve - FerrariChat.com

Step 2: Remove the bushing opposite the actuator rod (used a dremel), lose the ball and re-weld.
http://www.ferrarichat.com/forum/348-355/391007-bypass-valve-has-balls.html

The sound of the exhaust is so much more satisfying now that it is not in competition with the bypass valve buzz. The Capristo is the obvious replacement solution, just still overpriced, especially as compared to this repair.

The fixes here take about 1-2 hours including removal and reassembly. Most local auto repair shops will tac weld the bushing back into place for $20 or so.

 

The valve closes as soon as the vacuum builds up....which is a few seconds after you turn the engine on.

if you floor it at idle, you should hear the difference when the valve opens...around 4k ish

the biggest difference i found is the way the valve seems to open .....smoother ...although that is not necessarily the case as all is controlled by the ECU, but the noise comes on slower/more natural vs the oem valve...i am guessing this is due to the spring loading to open vs the oem way.

of course no buzz which distroyed the beautiful sound at idle.....

I am curious about the removal of the ball from the oem valve and why would that work/remove the buzz ,,,,when the bushing is the one worn ?

 

Hey, 355.

It's me... the PO lol!

I had the Capristo on another F355 and I had to make sure that I had the solenoids connected properly because the Caprist works in reverse... using vac pressure to keep the valve closed, then bleeding off vac pressure to open it, hence the vac leak sound you should hear when you throttle it.

 

Ahhh. Good news! I like reading your threads to see how she's doing. You're taking awesome care of her

Enjoy.