Possible fix for a noisy/rattling 355 exhaust valve

Thanks for the write up. Please let us know if this fixed the problem.

 

Mine whistles a little on start up, but goes away after about 10 minutes---My mechanic said that is perfectly normal...As long as the noise does go away..

 

They took an extra look at it during my last visit and even took the car for a drive--said it was ok...I'll have them look at it again the next time I go up...

 

f355spider,

Thanks for the great write up, very informative.

I took my exhaust apart as you suggested and it was very easy. I decided to take the same route as you did and remove the three nuts holding the vaccuum unit for the adjustment...but I ran into a small issue. There is a thin white gasket between the vaccuum and the mounting plate, which literally turned to dust, poof. Looking at the parts manual, I do not see a part # for the gasket. Did you run into this issue? Is there a substitute material that I might get at a local store, I want to make sure the car is perfect and I do not like shortcuts.

Also, you said that you created about 1/8" tension, is that a factory spec? I want to make sure that the valve works properly and does not have issues due to overtensioning.

Thanks again!

 

It was only about 1/16" thick at most, white in color.

I wonder if it is needed, for heat separation etc. I am going to see if the local store has a generic gasket material that I can cut to fit.

My valve had VERY LITTLE tension before the fix. I did notice that if I lifted the rod while the car was running the rattle went away, so I am hoping the bushing is good. There is a very slight amount of play in the bushing, but I am unsure how much is in the new piece as they may allow for heat expansion etc in their design, so a little play when cold may be normal.

 

I need to replace my O2 sensors as well, wouldn't this be easier now as the entire exhaust is visible? The car sputters at idle and a Ferrari mechanic told me the O2 sensors were to blame.

Can I just replace them with new units and they work or is there other things needed, like a computer system and tweaking after the installation?

Where are they located???

 

You have two O2 sensors in each cat for a total of 4......so you have to identify which sensors your mechanic is referring to and replace the correct ones.
It can get quite expensive and you might want to purchase them on Ebay to save some $.
As I have a 95 model, I have only 2 sensors in total and made the mistake of buying them at the dealer.......$860.00 later........the last New sensors I saw on Ebay went for $90.00 each.

Make sure when you re-turn on the power to the battery that you go through the 10 minute 'relearn' process for the idle setting.

 

Dave,

I agree, sorry!

Back on track...I was able to purchase some generic high temp gasket material at Checker Auto parts. I will post pics soon.

 

THANKS for posting this information - it was very helpful. IMHO that is exactly what FChat should be for.

I just did the same job - relatively painless - but I won't be able to road test it until some more snow melts from in front of my garage. Hard to judge just how much tension is needed so I tried to be conservative.

I was able to avoid having to remove the vacuum pot and got the ball end of the rod off of the socket without much trouble. The trick was judicious placement and simultaneous wedging of thin screwdrivers on both sides of the ball. A bit of penetrating oil helped loosen the lock nut.

 

Here is the gasket material that I found. Easy to cut with a rasor and scissors. The second pic shows the gasket in place.
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This is the gap showing the amount of pre-tensioning before tightening, which represents two turns from its original position. Is this about what you had pre-tightening?
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Cool. So this is a gap amount that might work. Time to tighten it down and re-install.

 

Very little, maybe 1/16"

 

Need some guidance here.....

I removed the bypass valve as described made the adjustment but having a very hard time getting the bypass valve to fit properly back into the Y pipe. Was there any trick to this?

 

The valve goes into the exhaust fine but won't fit back into the Y pipe. It was tight getting it out and I had to lightly tap it with a rubber hammer to get it loose. I may take some fine emery paper and go around the inside of the Y pipe and the same on the bypass valve to see if that helps.