Exhaust rattle

time for test pipes or hyperflows brother

 

It could be your bypass valve. They are known for being very noisy and a well known problem. The easiest way to see if this is it is to rig a little hook with a coat hanger and pull the valve open when it's idling to see the rattle stops. If it stops when you open the valve, welcome to the club!

Unfortunately, the factory valve is very expensive (around $1700) and will likely do it very soon after installation. There are a few people on here with the Capristo valve that have given it high marks and much more affordable (around $950).

BTW, do a search on 355 bypass valve and you'll find tons of good information including info on the Capristo valve.

 

I got tired of all the rattle and ordered a capristo valve last week. Will hopefully get it next week, will tell you more later...

 

The bushing wear in the valve causing it to rattle. I have someone who fixes them for me.

 

I'd love to learn more about this. Would you mind sharing the info?

 

I had the same problem about a week after I got my car, it was a cat.

 

You can see the cats with the engine lid up. When your car is cooled down reach down and bang lightly on each one with the side of your fist, if the internals are broken, you should be able to hear the rattle, yes this is the same low tech method we use in the shop, obviously we confirm the problem once the suspected cat is removed. If you do have a broken cat, it is important to attend to it very quickly, it can create a lot of heat from the added backpressure, and its guts can get stuck inside your muffler.

 

I just installed one on my car. You should have more space to work with on your vacuum control bracket (since, I assume, it's a Euro car). Here's the link:

http://www.ferrarichat.com/forum/showthread.php?p=139486822#post139486822

 

+1, I have the Capristo. BUT, you can adjust the oem valve if it rattles. Part of the problem is the spring preload weakens over time. You can remove the valve from the car, and see the adjusting rod. Adding a couple turns of preload can eliminate the rattle most times (too much preload can keep it from opening too). Eventually you will run out of adjustment, or it is the bearing mentioned previously, and you simply must get a new one.

 

I also had a rattle from the heat shields on the Y pipe...I removed it and had them tacked down with a welder...all good now.

 

When I first got my 348 I noticed it had that same issue. I went over to BT's and he put some epoxy up on where the rattle was coming from. All set!

 

Found and fixed one last night.

On mine. (1995 355 Spider) The left side heat shield between the Y-pipe and the CV-boot was so close to the Y-pipe that when the motor hit a resonant frequency (about 1,100 rpm), the heat shield would vibrate and buzz against the Y-pipe. Just bending it slightly downward (about 5mm) with my hand, got it far enough away from the Y-pipe that it doesn't make noise anymore. I still need to double check that it's not too close to the CV-boot now.

 

Yeah, I am not really liking your mods, but you should still post pictures and a sound clip for your 355 brothers!