heinrich

The same way the oil from the crank does -- splashing, sloshing, windage.

SharkSkin

I guess I don't understand this post at all then:

https://rennlist.com/forums/showpost...8&postcount=49

Upon re-reading it seems that the added filter does have a bypass, which would have allowed all of the metal bits to be pumped around the filter?

Heinrich, I'm not sure how far up into the heads this stuff made it -- but I'm having trouble visualizing this. Bill, was there debris inside oil passages, tensioners, etc in the heads, or only laying around up there outside of those areas?

heinrich

Dave ... i don't know what they found, just saying we KNOW the 928 likes to slosh and aerate oil and it can GULP oil from the passenger's breather hose. So, it stands to reason that, THAT oil would contain the shredded bearing and crank metal? Please help me out

SharkSkin

H, since I don't know how much of that oil getting into the breather is coming off the cams vs coming all the way up the drain galleys and into the breather I can't answer definitively -- but my best guess is that most of that oil is coming off the cams since I think that it would be a lot tougher for it to come up the narrow drain galleys.

Hopefully nobody will mistake me for an expert on the subject.

heinrich

This much is certain Dave: That oil, is not from the cams but indeed off the crank

SharkSkin

I'll defer to your greater experience in this -- I'm still interested to know whether debris in the heads is only on the surface(splash/windage) or in the oil galleys as well. Either way cams/lifters probably suffered, at least on the lobes if not the cam bearings.

Bill Ball

Nope. The debris was inside all the oil galleys. There was none visible outside the galleys from splashing except in the pan.

worf928

Front-side thrust bearing wear...

One more reason to like the fact that 928s do not have a starter-lockout on the clutch. After reading this morning's posts to this thread, I cringed when I started one of my other cars that has a clutch pedal starter-lockout. No oil pressure at start, and only residual oil on the TB.

How many folks always start their 5-speed in neutral with the clutch engaged?
I always do - even before this thread.

heinrich

I have driven manual transmission cars all my life, and would never consider starting a car in gear.

worf928

Maybe I didn't post clearly enough. A lot of cars have a starter-lockout that will not allow the starter to turn unless the clutch pedal is floored and the clutch is disengaged. With the 928 (and our old 16v Scirocco) you can start the car with the clutch engaged (better have it in neutral) and thus there is no pressure (other than clutch pedal pre-load) on the thrust bearing. On the other hand, our Audis and CarChick's Z06 have a clutch starter-lockout and thus when you start the car you will be dragging the crank back against the thrust bearing every time.

I would think that this isn't a really big deal as long as the car is driven regularly. But, if the car sits for a few days and the oil film drips off the bearing surface you'll be scrapping the crank over a dry thrust bearing when you start the car with the clutch disengaged - which you have to do if you have a newer car with a clutch lockout on the starter.

Am I making any sense?

heinrich

Dave you are, and I got that, your first post was just as clear. What I'm saying is, I've never done that, guess I've never had such a car Personally I would bypass that silly option.

Charley B

Got it! Start car in nuetral with foot off the clutch. Right?

FlyingDog

It's so habitual from my Jeep and other cars that I almost always do it. I'll have to retrain myself. I'll add disabling that "feature" to my rewiring/disabling list for the Jeep.

Steve Cattaneo

[QUOTE]There is no adjustment in clutch push rod. If factory did its job right there is very little force applied to fork when clutch is disengaged. Its needed just to keep push rod from falling off from fork. How big this force is can be estimated by releasing clutch slave cylinder mounting bolts.
__________________
Erkka







I am aware of the fact that 928s with manual transmissions have an automatic clutch adjustment, as do 98% of all hydraulic clutch systems, for this fact, the clutch pedal free play travel can not be check at the pedal.

This is why the master cylinder PUSH rod (not the salve cylinder push rod) must be adjusted correctly; preloading the push rod by one turn, will position the master cylinder push rod to were it will barely touch the master cylinder piston, any more (not adjusted properly) would pressurized the salve cylinder, in turn disengaging the clutch, almost like riding the clutch.

FlyingDog

The three slaves (two cars) I've pulled out all had significant force pushing on the fork and little or no preload on the master. Both were dual disk clutches with on and off dragging problems and fragged throwout bearings.