44 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
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Reported or suspected cause
caused by one pull
Reported cause
No successful repair reported for this finding.
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Reported cause
I still doubt that the problem was caused by one pull to the rev limiter - it was coming sooner or later.
Leading evidence: 'caused by one pull' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'caused by one pull' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check crankshaft endplay' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed · Original poster
Pistons cleaned of carbon with Easy Off and then dunked in the parts washer.
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Suspected cause · Original poster
I don't know for sure what all the wear is from but I suspect its been going on since my last oil change.
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Suggestion
After installing new thrust bearings & the crankshaft in it's carrier, check crankshaft endplay!
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44 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261026T090147Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Ouch Nick,
Sorry to see that!
The same thing was posted by another Rennlist member recently, but I can't remember the name of the thread. I'm afraid you need open heart surgery and full cleansing to get her back to safe running condition. IMHO. But I'll let the more experienced chime in on this one.
One of the M96 Modes of Failure.
Cause? Several possibilities - installed backwards so the oil grooves do nothing.Very heavy 'performance' clutch,bad oil choice, many others?
The crankshaft carrier may have been damaged also. It is much softer than the crankshaft webs.
Find a junk engine and make one from two ?
Thanks for the replies so far! I hit the rev limiter between 2nd and 3rd and it started ticking, then clanging... I'll be disassembling this week to see the extent of it
Don't know yet what direction I'll take.
Well, it definitely wasn't the waterpump. Sorry to see this. I was hoping in your other thread it might be something minor. I still doubt that the problem was caused by one pull to the rev limiter - it was coming sooner or later.
kc, I do agree. Just a quick look at the residue I found confirms that its been a ticking time bomb. I wish I had researched the car more before I bought it, but I've had two summers of fun with it since. I put an LN bearing in it before I drove it and worried too much about that issue to pay attention to the others, I guess.
I'll post in the other thread when I think I have more answers.
What other issues did you have and what evidence did you see that made it a ticking tomebomb? +1 that hitting the limiter especially not a mechanical overrev since you were going from 2nd to 3rd, not the other way around would have caused the problem.
I shut it down immediately when I heard the noise coming from the motor. Upon inspection I found the oil to be very muddy with fine metal particles, magnetic and non. I don't know for sure what all the wear is from but I suspect its been going on since my last oil change.
Looks like the rod bearing on number one was somehow oil starved and spun. The crank, rods, carrier, cylinders, chains, lifters... everything... is in remarkable shape.
After careful consideration by all of my trusted but not Porsche experts who have over 100 years of combined experience with rebuilding every type of combustion engine from aircraft to tractors, this POS is getting rebuilt with nothing more than new bearings.
Simple, she gave up years ago and left and I had the good sense to not replaced her
But seriously, I never imagined these parts would end up on the table. They were great company for dinner last night!
Manually probe the hole in the case where the oil filter attaches, to check for more metal debris. Have the case & heads ultrasonicly cleaned to clear oil & coolant passages, otherwise you WILL have metal shavings circulating throughout the engine. After installing new thrust bearings & the crankshaft in it's carrier, check crankshaft endplay! That may be what liberated the thrust bearing on your last visit to redline city!
I think it's pretty simple. My theory is that the pick up screen got clogged with the cam tensioner pad material and that caused the oil starvation, that then caused the bearing to spin.
I took the crank to my crankshaft guy. Because oversize bearings are not available, he wouldn't touch it. So.... I polished and polished and polished.
I have a nice parts washer and I've been cleaning debris as best I can. The oil cooler is getting pitched because that's impossible. I'm cleaning the lifters in mineral spirits with compressed air. Those worry me the most right now
As far as oil pressure, for the three years I've had this beast, the gauge was always low at idle. I like Imo000's theory best, but my tensioners are all 100% Everyone here agrees number one was oil starved somehow. The connecting rod bore and bolts show no sign of stretching, but you can see evidence of heat build up.
Any ideas on why the thrust washers popped out? Crank end play is in tolerance with a mock up of new washers.
The debris in the screen was plastic?
Is that polished journal round, flat from one side to the other and free from bearing material? Is the cranks straight (they tend to bend when a bearing is spun)?
My crank guy wouldn't even check it for straightness because he said he'd be at a loss on getting it straight.
The best I can tell on a couple of vblocks with my dial indicator on the mains, it's good in straightness. As far as the journal goes, with my best mic I get the same diameter all around. I've got all the old bearing material cleaned up (about an hour per journal).
I'm thinking now that maybe the thrust washers spit out first, broke the plastic IMS wiper cage (its damaged) and those frags are what you saw. Sound feasible?
The colour of the plastic bits fromt he pick up screen matches the missing chain ramp material? What does the thrust washer recess in the bearing carrier looks like? Any signs from the washer getting ejected?
The bearing carrier is completely undamaged. The pick up screen is mostly clogged with sheared bearing material from the number one rod bearing.
As best as I can measure, the original thrust washers were worn about .005 - .009 each compared to my new ones.
I spun a bearing on my crank from the connecting rod bolts loosening up. Took my crank to Eds Crankshaft in Hayward, CA. He welded up the journal, re ground to spec and straightened. I think it was about $250.
Ed's crank work has been doing great work for many years, we had him do work on some 15 liter cranks work... they know what they are doing, you just can't cheap out , have it done right. we were losing cranks to mechanics using 3M cleaning rotary pads on oil coolers and seal housing and the particles were very hard from the pads. finally had to remove all pad from every shop.
I want to add these cranks will see a million miles at 18.0:1 compression ratio
Pistons cleaned of carbon with Easy Off and then dunked in the parts washer. Not bad for 60K miles.
Cases washed with my power washers and bore brushes. Couldn't find anyone local who would chemically clean them so I did it myself.
I never realized how many people freak out when you say the P word. "A Porsche? No, I won't touch it."
Parts on order from Pelican, Suncoast and PartsContainer. Assembly starts when they all arrive.
I've had my hands in lots of engines, but I must admit this thing is about as weird as they come
Here's the happy ending. Less than $2400 in new parts
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