I’m sure some of you guys knew what was causing the rattle of the bypass valve however I wasn’t sure until now. I took off the end cap that was welded on and found a little steel ball; I put the end cap (bushing) back on without the sphere and no more rattle. Now let me clarify something; when I say no more rattle I mean no more when I take the valve in hand and shake it rattle. I haven’t had the chance to test in on the car yet and I’ve got a strong suspicion that part of the problem is the y-pipe heat shields vibrating causing most of the rattling or buzz saw type noise. Once I'm able to install the valve and test it I will know if it fixed the total problem. I’m not really sure if the valve will continue to operate normally without the ball but for now there are no problems. I think the ball is there to try and keep the shaft centered in the bushing. Like I said no issue yet but my guess is the shaft will eventually stop being able to rotate as it wears on the bushings. Anyway I just wanted to share what I found in case anyone else was wondering what caused the rattle inside the valve. And since I hadn’t seen a pic on the forum I figured this would help out. Image Unavailable, Please Login
interesting....keep us posted......as long as there is no movement between the bushings and the hub (ie: the butterfly does not wiggle when you assemble all together and it is tight) you should be OK.....probably used to center the shaft...but why this design ! Although a simple system.....but soooooo annoying !
Less likely to bind or become frozen with corrosion, but if removing it works then it was over thought which happens on these cars in some places.
Extreme, You might want to look at the design from Carpisto with the sping loaded end...maybe you can replicate it. Also, i noticed that the "cap" that goes on the ball acts as the bushing itself that fills the space in the hub and keep the shaft straight.....if that is worn by a mil....the movement/rattle happens.....that must have been the bushing I tapped slightly when i fixed mine...using ta chizzle and hammer.....without dismantle...... Maybe you can take this to machine shop and have them remove some material and create a spacer that slides on.......make sure they use high temp material. Keep us posted on your research
A friend of mine machined a new "cap" and through a bit of "trial and error" came up with the correct thickness cap to get rid of the slop and eliminate the rattle. He said his first attempt...after the engine got hot, it bound up and stuck open. He removed the cap, milled a tiny bit off and rewelded it back on....and has worked perfectly since.
Any ideas on how to stop the y-pipe heat shield buzz? Mine makes a racket from 2700-2800rpm. Drives me crazy!
My theory is that it only vibrates at the lower rpms since at over 2800 rpm with 80% throttle the bypass valve opens and then the gases flow freely through the pipe. I’m guessing the heat shield could be tack welded in a few spots to stop the vibration. I haven't had a chance to get back working on the bypass valve.
My temporary fix was to use a couple ss hose clamps to hold it down...not very elegant, but it stopped the rattle. The next time it was at Ferrari of Seattle, they properly tacked the shield down for me. That shield is really thin metal, so takes a bit of skill to do it right.
It's when the car is cold, then I limit my revs. Makes for a painful-sounding warmup! Once warm, it screams properly.
At start/warm up, this horrid noise begins for several minutes that embarrasses me and causes me alarm as to figure it out. Exploring some threads and posts has not found me a solution as to what it is exactly and where. Listening at the side air inlets atop the rear fenders the sound is magnified, listening in the engine compartment gives no clue to location (hearing impaired somewhat). Can you give me assistance on this issue? The ratteling and banging sound stops when warmed up and throttle is used when starting off. I am really at a loss on this and the embarrasment from the sound wants to make me keep the cover on the car. Has it to do with exhaust, tho it sounds loudest from the intake inlets, or intake system etc? I have been unable to locate any valve item( with ball?) or a shaft vibrating as mentioned in some posts. I plead my ignorance here and will wear the dunce cap cheerfully if I can stop this horrid, embarrassing sound. Public post or private e mail, anything to aide me here. Only on start up when cold and lasts for several minutes, sometimes on startup when warm but stops after throttle blip or application to start off in gear. Only at idle speed/start
Hi i seem to have the same problem,it only makes the noise after warm up after letting it idle for a few min,then goes away.My car is a 99f1 i'm thinking throw out bearing
You guys should start new threads with these question as not many are probably seeing them in here. You should be able to get some advice if you start a new thread. Sorry I don't have the answers for you.
