rmc1148

Almost all motors have some potential weak spot but overall the 996tt seems to hold up better then most.

Kevin

GT3/959 IMS is a very good thing. It's not a drop in, but with some machine work it's the ticket.

Motul has changed it's formulation. It's very similar to M1 5W50..

Kevin

All of us owners need to look at the oil filter for metal. Changing the oil at less than 5000 miles will pay it forward. It's sad to see these failures. Get your oil tested at Blackstone. If you have metal or a noisy IMS run Mobil TDT 5W40 or Rotella T6. These two oil have more anti wear agents and do well. If you are in warm climates, 5W50 should be the oil of choice, unless you fit in the above group.

Edinsf

Kevin
I did cut open my oil filter upon your recent advice and what I see is about seven minuscule bits of aluminium.
I ran a magnet in the crevices and it did not pick up any metal.
It would be great if I could mail it to you and you could have a look at it. I would include any amout of cash in the package to compensate you got your time.
Also I'm going to send my oil sample off to be analysed.

Macster

What in the world are you talking about? You brought up air-cooled engines.

Edinsf

What do you mean Mac?

nizzki

I called the shop this morning, they dropped the engine enough to see what was going on in there.
As expected, the chain had snapped. One of the valves was bent, but apparently the piston looked fine.
They also said that the residue oil in the engine didn't have any metal in it. There were only a few little nicks where the engine hit the case after it snapped, no major gouges in the case. They haven't been able to find the missing link, so they're still looking for it while assessing the amount of work required to rebuild it.
Either way, so far it apparently looks promising.

nizzki

Here's a couple pictures so far. They were able to find the last piece of the chain, so there shouldn't be anything metallic flying around there anymore.

Macster

Broken chain. Was there a money shift or did it just break?

The scavenge pumps have to be checked for any metal trash. Finding metal in the scavenge pumps is a black mark against the engine being a good rebuild candidate.

The end combustion chamber doesn't look very good. Load of deposits.

Hope the engine is salvageable.

nizzki

no money shifts involved, especially since it's a tip. it actually happened at very low rpm as I was coasting downhill at a leisurely 20mph half a mile away from my house.
They looked at the pumps, that's where that little piece of the chain was. there was no other metal in sight.
I asked about the carbon buildup, apparently they cleaned the other ones off a bit because they got covered with some liquid when they were taking the head off.

Flat6 Innovations

Its a chain deficiency. We see it with all modern Porsche engines, including the Cayenne and these Mezger engines. None are as bad as the M96, we had 4 broken chain jobs here at once last year.

There's different grades of chains from Iwis, thats the biggest difference along with zinc content in oil.

Kevin

Jake for this engine platform, I only know of two grades of chains. One coming from Porsche Motorsports and the other coming from Porsche which includes Genuine Iwis chains. Unlike the multiple offering for the standard Air cooled engine.

Folks, here we have another subtle statement mentioning that a HIGH zinc oil run in your engine from day one can "add" a level of insurance against these failures.

Flat6 Innovations

The Iwis chains can be had in different grades as well..

nizzki

The stock Iwis chain failed, i hope there's something more durable.
Either way, I really need to stop googling around for timing chain stuff because i keep finding new failures. Not a great sampling, but still discouraging. I'd be mega-pissed if it died again.

Flat6 Innovations

Any chain can fail in any engine. Chains are lubricated by boundary layer protection, much like a camshaft or lifter since they are metal on metal. Your best line of defense is to have the chains cryogenically enhanced, then use a very good break in oil, like Joe Gibbs BR, for a few hundred miles, then stick with a high zinc engine oil afterward.

We've never had a chain fail in one of our engines, at least not yet- I am sure its coming.