ErnestSw

If it's not an oil issue what is it?

AO

I would think it's a lack of oil issue.

docmirror

I don't know, but if it's an oil issue, why does it affect only the 2/6 rod journal? I've seen engine oil failures and it's generally catastrophic in different areas.

ErnestSw

What are the other possibilities?

docmirror

Well, 'I don't know' is an answer, although it's not a very useful answer. Everything that follows is pure speculation. Since it's always on the 2/6 rod bearing, and apparently the 944/68 suffers from the same journal failure, I'm thinking some kind of phugoid moment that causes that journal to vibrate. I think the smaller engine has a counter shaft for some reason, it could be related. Other physics answers could be related to the trouble with reciprocating engines and instantaneous torque inertials.

That's a few minutes sketch. By no means exhaustive, or tested, just a few ideas.

ErnestSw

So some kind of mechanical harmonic that affects the crank and causes a flex that closes the lubrication space. Sounds plausible. I suppose the same harmonic could affect the oiling pattern as well in terms of flow rate, foaming or cavitation.

Lizard928

Doc, to answer your question, to pull the Cam cover bolt a 5mm is needed.

To pull the Cam journals, you require a 12 point 8mm allen key, also known as a triple square.

docmirror

Thx Lizard, that's the tool I'm trying to find. Hopefully I can find that 8MM 12 point. Northern tools doesn't carry it, and I haven't found one at a local big box hardware yet.

Lizard928

Find a place that carries "Lisle" tools, they can order it in for you.

Rob Edwards

When removing my flywheel I got a 4-piece set (6-8-10-12 mm) of triple squares at the local Kragen autoparts store for $10. They're made by powerbuilt, #648599. Here's a link to the set:

http://centralnevadatool.com/powerbuilt-648600.html

I bet any of several semi-decent FLAPS will have them/can get them.

ROG100

Doc,
I have a set of triple squares for you to borrow.
May involve drinking beer though.
Roger

SeanR

I'll show him how to use them, for a beer.

Ed Hughes

I had my 911 crank cross-drilled and grooved at the center main journal. It's a potential weak point at high sustained RPM's on flat 6's, and it is related to cavitation, which was mentioned above as a possibility. Porsche wasn't infallible, and potential weak spots can surface when engines are stressed. Let's face it, it happened at the track, and the car certainly wasn't new, with low miles.

Did somebody mention something about beer drinking?

docmirror

Cavitation occurs when liquid undergoes change of state to a gas during low pressure. I think it's simply air entrainment. That is when air isn't separated from a fluid that is in motion, and the air expands under decreasing pressure during it's trip through the oil circuit. I knew what you meant though.

I have the 12pt tool, but it's damaged and won't take out my cap bolts. I have to find another one. If anyone shows up here, they automatically get beer, and a sandwich. Just ask Curry.

ROG100

you busted my brand new never used tool already !!!!!
This will cost you more than beer 8>)

You have not busted my media blaster as well have you??