fpena944

After reading a thread on a high mileage engine blowing up due to the timing chain, I have to ask the question...Is the chain considered a maintenance item? Can it be replaced by the home mechanic?

I remember on my 944 I had to replace a plastic guide, is that same issue present on the M96?

I'm going on 165k miles on my 996 so if this is something I should be looking at I'd like to know!

Southern Man

I'd like to know too. 158,000.

Montychristo128

Gents,

Here is an older thread on the same subject. Block needs to be removed to change chains and therefore it might as well get clutch etc etc.

As I understand there are also plastic chain guides that will wear over time and eventually fail.

https://rennlist.com/forums/996-foru...placement.html

Flat6 Innovations

Timing chains can fail at low mileage. I have caught a timing chain in the process of failure at 38,000miles while pre- qualifying for an IMS Solution job.

We developed master linked timing chains, and have a procedure to install these without engine disassembly. The original chains are constant, and have no master link. More and more people are opting for this to be done during our IMS Solution retrofit procedure.

While these failures are not viral, they make up about 10 of the failures we see per year. Often times these are misdiagnosed as some other failure, even an IMSB failure. This is because of the symptoms being similar to an IMSB failure.

A broken chain is one of the nastiest failures that can occur, its #2 in the damage department, only one upped by valve seat failure, in regard to how bad the collateral damage exists.

The original chains are made by Renold, and are not the quality of the Iwis chains.

ohlins8990

Any thoughts on the early vs. late style chains?

Flat6 Innovations

The only difference is the chain length... The rollers, width and material, and manufacturer are exactly the same.

ohlins8990

I thought the older cars used a roller chain, and the later used a tooth style.

Flat6 Innovations

Yes, for the IMS drive chain only. The later style fails differently than the early style, as they will typically just fill the oil with debris that takes out other parts within the engine before they snap. The early style won't do this, it just loses a roller, then snaps.

That said, these IMS drive chains are deep at the heart of the engine and cannot be accessed without full teardown. We see better service from the IMS drive chain, than the main timing chains that drive the cams, via the IMS. These are what I was referring too earlier in the thread. I'd only be concerned with these main chains, and on 5 chain engines I am more concern with the simplex chains that drive the intake cams, via the exhaust cams. These are the most probable for wear.

fpena944

So in other words although this is a method of failure I probably shouldn't worry about it until it's time to rebuild the engine.

Since the block has to be opened up anyway I may as well go full-on rebuild at that point in time.

Schnell Gelb

I wonder if timing chain failure is aggravated by the extended service interval Porsche recommends for oil changes(15K miles) ?
If so, it is yet another point in favor of the more frequent LN-recommended service interval. Cheap alternative to a chain failure !

fpena944

I don't follow those intervals anyway. I use 5000 miles between oil changes and even less if I track the car.