Junior64

I just recently picked up a 2001 996 Carrera convertible with the 3.4 engine.
When I start it up after it has been sitting, it sounds like the chains rattle for a few seconds and then it goes away. I've heard some people say that this is normal for this engine. I'm still wondering if there might be an issue with the chain tensioners? Does anybody know for sure if this is normal for the 3.4 engine? Any help would be greatly appreciated.

Barn996

Hard to diagnose without hearing it, how many miles? Mine is a bit noisy initially, but dissipates after a few minutes. Must be the next forum scare with our 996s, check out the search button because it is a recent ongoing topic.

Dharn55

Could be the chain tensioners. They are hydraulic and can leak down when the car is off then take a few seconds to pump up with oil pressure. Not uncommon. How many miles are on the engine?

Junior64

The car has 74K on it. the engine runs great. But when I heard the chains rattle on start up, it got my attention. I honestly haven't had that much experience with the 3.4 engine so I want to make sure I'm not over looking something.
I've also heard all kinds of horror stories about IMS bearing failures

Dharn55

IMS bearing rattle won't go away. The tensioners are not very expensive, less than $100 each. The 1-3 side and the IMS to Crank are easy to change. The 4-6 side is harder as the tensioner is under the AC Compressor and a bracket. There is also some debate on whether to use the old style tensioner on the IMS to Crank or the newer style. Do some searches and you will find lots of discussion on this.

ivangene

I agree with Doug, chain tensioners is high suspect - I hate to ask all the same old questions, but what oil, when was it changed last, any service history, did you get a PPI, do you have a place to take the car too (an independent shop) that is willing to look at it for you and help you understand what you are hearing?

anyhow welcome

Junior64

I bought it off one of my customers where I work. And I personally inspected the car myself. It needed a clutch and a few minor cosmetic issues. I installed a new clutch, and gave it a nice detail. I believe the last oil change was with 5/w30. I work on a lot of imports at my shop, unfortunately not many Porsche 996s
so this is a new learning experience for me.

Macster

Drain that 5w-30 out and switch to a 0w-40 or 5w-40 or even a 5w-50 oil. Mobil is an approved oil (though not all Mobil 5w-40 oils are approved).

Any approved oil will have A40 on the bottle somewhere.

If you don't like Mobil there's Castrol, Shell, Pennsoil/Quaker State, Motul and so on.

A bit of chain dragging noise like a small link chain is being dragged over a piece of lumber or a log is normal for these engines.

They have quite a bit of cam chain and these long runs of chain have an oil pressurized tensioner on one side and a guide on the other and until the oil pressurizes (it can take a few moments) the chains are running with a bit of slack and will make some noise.

But get the oil changed first.

Sincerely,

Macster.

logray

I replaced my 99's tensioner's with all new ones.

I also changed to Castrol 5w50.

I also replaced all of the lifters.

I still get a little startup chain noise (present before/after I would consider normal).

Gone is the tick tick tick though at startup... now it's more of a healthy "stuff filling up with oil" sound that disappears quickly (within 10-15 seconds or so at most, or even less/not present on a warm start or driven daily in warm temps).

Of course, the valve job and 5 new guides that were completely shot probably didn't help that situation much (sarcasm).

Junior64

A special thanks to all who have posted replies to my post. An oil change with 5/40 or 5/50 is my next step. I will report back with the results.

captain caveman

My car also has this rattle it's done 93k and sounds like a diesel for the first 3 or 4 seconds.
I've read some people say its normal but is the any chance of the chain jumping a tooth if it's slack?

brianmch

A chain can jump teeth but then you'd probably have some driveability issues as the timing would be off some.

Schnell Gelb

How would that affect timing chain rattle?

captain caveman

I would expect a lot more than just some issues if the chain jumped 😅
my question was people say its normal but I'm sure it wasn't normal when new and if the chain is slack when it's first started what's the chance of it jumping a tooth as it's something I would rather avoid happening.

mayday1

Mine ('99, 3.4L) would rattle a bit on start up since I only run the car every few weeks in the summer, and it mostly sits in the winter.

This year, before I start the car I pull the fuses to the injectors and
fuel pump, crank the engine 10-15 secs. Reinstall the fuses,
then crank again and shut off the ignition soon as it fires up.
Do that a couple of times and start the car normally, and
there is no rattle on start up, the car runs butter smooth
right after start up.

Kind of a pain, if I have to do it often I'd probably figure out a way
to switch off the fuel pump and ignition without having to fiddle with
the fuse box.