Possible fix for a noisy/rattling 355 exhaust valve

Mine went back into place easily.

Now that mine is back in place the rattle is significantly reduced, but still there, I might have turned the valve out one more time to tighten it up a bit more. Upon test drive the car does not seem to have the power at the top end, also the "scream like a banshee" is no longer there. I do not want to push the car for fear that the valve is not opening and I do not want to cause damage to the engine.

Is it possible that the valve is not opening? How can I check for correct operation???

 

To check the valve operation, just start the car (and let it warm up so you're not revving up a cold engine) and have someone stand behind the car with the rear hatch open and look down at the bypass vale from above. When it's revved up (4K RPM+) you should be able to see the valve open and close.

 

I did'nt know the valve would open while the car was rev'd while in neutral.
I thought you had to have it in gear. ????? Has anyone tried this on a 1995 ?

 

I will try testing tonight. I ALWAYS warm up the car before driving!!!

 

I warmed up the car and had my wife take it to 6k, the valve does not move. The car also has a muffeled sound. When driving it has the same muffeled sound and the upper end power seems reduced, so I am sure it is not opening at speed either.

Perhaps I need to take the assembly back apart and unload the spring a bit and live with the rattels.

The valve is vaccuum driven, did I need to bleed anything???
Any other suggestions???

 

Bump!!!

 

I confirm that on my 97's 355, the by-pass valve open even in neutral. You need to rev a "bit" the engine ;-)

 

I was up at 6,000, it was not moving and the engine was muted.

 

Is it safe to remove the vaccuum hose while the car is running to see if there is any suction at 4-6k?

 

You will have to check the valve during rev up (and you have to rev up quickly). If you keep the rpm at the same level or only rev up slowly the valve will close again. This is at least what my '95 model does.
Driving with a always closed valve is not a good idea if you rev up hard >4000 rpm.

 

I took off the airboxes and shiels again so I could see the valve clearly. With my wife revving the car quickly the valve does not move. I also checked the veccuum hose at the bypass and tightened it,still no movement. Playing with the valve I noticed that it would take quite a bit of pressure (a few more turns out) to stop the rattle. The amont of rattle is livible at this point, if the valve worked. I did manually open the valve, put my finger over the vaccuum port and the valve stayed open, so it is not a torn diaphram.

I am going to get contact cleaner to clean the solinoid, and see if that helps. I could loosen the valve again to see if that fixes the issue, any other suggestions?

 

From what you describe , the first thing I would check is the vacuum.
Goto to your local auto parts store and pick up a cheap vacuum gauge and see if there is vacuum on the line as you rev the motor (take it for a drive if possible..... and run it through the rpm ranges for this test and watch the gauge- but I would wire your bypass valve open for this test).....if no vacuum, then the problem is NOT your bypass valve but rather you need to check the vacuum lines and air canister(behind the right rear inner wheel well cover).
You need to eliminate the basics before you proceed further.

I just had a thought....before you do anything, why not adjust the bypass valve shaft tension to its original adjustment and see if it works as it did before......

 

I am going to put it back to the original tension and try that, back to super rattle!

 

For the short term I have it wired open...no time to play. During this summer, when I am redoing the interior, I will probably get the new capristo and take care of the engine as well..