The alpha and the omega

[Brucelee]

Several years ago, I sold a 2000 Boxster to my neighbor. She loved it so much, she went out and bought a new 04 last year.

On Tuesday, the half shaft let go and, well, in short, goodbye to the engine.

Talk about upset, she is!

The good news is that the new engine should be in by Friday or Monday, no charge.

The bad news is the car is now "suspect" in her eyes. She wants to know why an engine with 10K miles on it should fail while sitting at a stop sign.

I did not have a good answer for her.

Is Stuttgard listening?

[mach schnell]

sitting at a stop sign, eh? maybe she wasn't supposed to proceed past the stop sign - in other words, perhaps devastating consequences would have ensued had she continued on her journey. Maybe the blown engine kept her (or somebody else) alive that day. if i could only get that phonebooth time machine sitting in the garage up and working!

[Brucelee]

Originally Posted by mach schnell

sitting at a stop sign, eh? maybe she wasn't supposed to proceed past the stop sign - in other words, perhaps devastating consequences would have ensued had she continued on her journey. Maybe the blown engine kept her (or somebody else) alive that day. if i could only get that phonebooth time machine sitting in the garage up and working!

You are right.

Perhaps the Porsche engineers are so god like, they could foresee this tragedy about to happen. Hence, the design-in failure to keep her safe!

Why didn't I think of that?

:dance:

[MNBoxster]

Originally Posted by Brucelee

Several years ago, I sold a 2000 Boxster to my neighbor. She loved it so much, she went out and bought a new 04 last year.

On Tuesday, the half shaft let go and, well, in short, goodbye to the engine.

Talk about upset, she is!

The good news is that the new engine should be in by Friday or Monday, no charge.

The bad news is the car is now "suspect" in her eyes. She wants to know why an engine with 10K miles on it should fail while sitting at a stop sign.

I did not have a good answer for her.

Is Stuttgard listening?

Bruce,

By half-shaft I think you're talking about the Intermediate Shaft. In '03 I believe, Porsche re-engineered this piece and went from a Double- Bearing at the end to a Single-Bearing one, supposedly to reduce vibration.

The intermediate shaft drives the oil pump. When the Intermediate Shaft breaks, a small stud which protrudes from the Intermediate Shaft Flange Seal breaks off and rattles around in the Bell Housing - Not Good!

From the flywheel side of the engine a 13mm nut is centered in the Intermediate Shaft Flange Seal. That nut and the stud its attached to is what breaks. This causes Oil to pour out of the hole left in the middle of the Flange Seal.

At this point in the Failure, the Crank is still driving the intermediate shaft so Oil Pressure is maintained. But, once the engine is stopped, Oil just flows from it similar to catastrophic RMS Failure.

The Intermediate Shaft also drives the Camshafts. The Intermediate Shaft has two Sprockets at one end and one at the other . The end with two Sprockets has one Sprocket for the Drive Chain from the Crank, the other drives the Cams. So, in addition to piercing the Oil Flange Seal when the Shaft breaks, causing the Oil to drain from the Engine, it can also interupt the Valve Timing. The M96 Engine is an Interference Engine and so when breakage occurs, you can also bend Valves and Crack Pistons - also NOT Good.

Unlike RMS Failure, which tends to occur on Cars under 20k mi., the Intermediate Shaft can fail even at higher mileage, but is less common than RMS issues. Although not restricted to post '02 models, it does seem more prevalent in them. While less common than RMS Failure, Intermediate Shaft Failure almost always destroys the Engine when it goes. There is no maintenance or Driving Practice known to reduce the likelyhood of such a failure. Hope this helps...

Happy Motoring!... Jim'99

[limoncello]

First, great explanation, Jim.
Second - wonder if they'll go back to a double bearing. Maybe a little vibration is not so bad after all?
Anybody know if there are any major engine redesigns in the works, or is it status quo for a few more years?

[Brucelee]

I find it kind of appalling that this kind of design issue shows up on an engine that has been out since 1997.

What is Porsche's motto?

[70Sixter]

Porsche put us thru this with with the notorious cam timing chain tensioners that failed with disasterous consequences if you were at high rpm. Fortunately my 911 went slowly, albeit noisily.

And a stop-lite failure would probably not be catastrophic. Porsche finally fixed the problem with additional lubrication, but it was in the mid-80s (MY84 Ronzi said in earlier post)

[Finallygottaporsche]

RMS - all years
Cylinder Liners - 98-99
Intermediate Shaft - 02 and up

i guess youre screwed no matter what