Optical TDI

I recorded the knocking sound with a camera. The noise only lasts about 2 seconds. The master tech based it repair on that sound clip. They seem to like warranty work though.

ivangene

OK - ask him if you can have the "old parts" (or at least see them)

if he replaces the tensioners, they could be gauld on the sleeve...have him point it out to you.

Cefalu

My '99 C2 6 speed has the same 2 sec rattling on cold start if I have not driven the car in a week or so. What are the parts that might be affected? No rattle when I am regularly driving it.

Dharn55

The rattling is not that uncommon on the 996 engines. The tensioners are fed pressurized oil, so when the engine is off they can go down some. When the engine is started the oil pumps them back up. Look at your oil pressure gauge, it takes a second or two to register pressure when you start the car, about the same time as the rattle typically takes place.

New tensioners tend to be tighter and not have any scoring so they don't leak down as much. They have also had some redesign over the years.

LN and Flat 6 recommend replacing all 3 tensioners with the latest ones when you do an IMS bearing upgrade. The three tensioners can be bought for about $200. As for the time to replace them, the two on the flywheel end of the engine should not take more than 10-15 minutes each. The one on the other end of the engine is a pain to get at. You have to pull the AC Compressor, loosen some brackets, then snake a big socket down in to it. Once it is loosened it is a tight fit trying to get it out from under the hoses and brackets and then get the new one back in. By the way the newer style at this location comes with a hex drive socket (allen wrench style) to make it easier to get at. For this one you could easily spend an hour or so.

Macster

Chain guides, chains, sprockets. Theoretically. But come on, a 99 that has been doing this since day one?

Worry about bird flu. Earth destroying asteriods. Space alien invasion.

Seriously, about all you can do if you can't drive the car more frequently is to ensure you use the proper engine oil, a high quality oil, of the right viscosity grade for your area, and keep the oil reasonably fresh. I've done this with my 02 Boxster and it has accumulated nearly 234K miles. Sure, there's a bit of chain noise (sounds like a heavy chain being dragged over a log) at startup, if the engine has sat a while, but the noise goes away in must one or two seconds.

If you want to try it, since you have some history with car, add a bottle of Swepco 502 oil treatment to the engine's oil. Swepco 502 I've been told helps quiet down engines during startup that don't get used regularly.

Sincerely,

Macster.

Jake Raby

Mileage isn't what causes tensioner issues... They get really sludged up and dirty due to design as there is only one way for oil to check into them and it doesn't check back out unless it bleeds around the side of the piston.

Typically they can be pulled, soaked in thin hot oil and cycled to purge debris from them and they operate like new. This should be done at least once every 3 oil services.

Start up noise is normal when these wear or get dirty.