Rattle rattle - if it is not the heatshields, what then ? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

mylamb · 09-03-2007, 08:57 PM

williamsf1,

It could be one of your catalytic converters. I had a frequent rattle that was hard to diagnose and we finally realized that one of the cats had disintegrated and was causing the rattle. In the US, Porsche cats are backed by an 8 year, 80K warranty. I don't know what it's like overseas but I don't think you would be covered anyway on a 98. Since you're going in anyway, ask them to check the cats. It won't be cheap if you have to replace one...

Good luck

williamsF1 · 09-04-2007, 02:31 AM

Hi'

Thank you for taking the time to help me out on such short notice!

Any tips for diagnosing the cat ? (I read about banging it with a rubber mallet.)

Would a cat rattle go away when it got warm ?

Price-estimate for a cat-replacement ?

Thank you

P-DUB · 09-04-2007, 07:02 AM

i thinks it probably the valve train waiting for oil. Once it gets oil (a second or so, it;s fine?). If you turn it on and let it run until the rattle goes away (1 - 2 seconds) turn it off, and then turn it back on again, is it still there or gone. If it's gone, it's the valve train or trane?

mylamb · 09-04-2007, 07:42 AM

Best bet is to get it checked out. Describe the noise and make sure you're present when they test it. It's very easy for a mechanic to go "I didn't hear it." I have had to sit with techs at even the most well reputed shops to point out the noise because they couldn't find it on their own - regarding suspension & exhaust work. I have heard of our cars rattling while cold but never experienced it myself (once the cat was fixed.) Not sure on 98's, because there are 2 & they may have different internals for later cars which have 4, but you should figure on $1200-$1500 if one has to be replaced.

Wret · 09-04-2007, 09:19 AM

I had an exhaust rattle that only occured when the engine was warm. It would go away in minutes so finding it with a rubber mallet proved fruitless. I gave and replaced the most likey suspect, the muffler, with a used one. The problem went away.

I have since dissected the muffler. There was nothing obvious flapping around in there. Maybe a baffle rubbed a certain way when the metal expanded.