[banditsc]

With the oil in the intake, I would look at refurbishing that head before reusing it since you will have it off. What is the mileage on this motor?

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[flash]

this is why i wanted the valves checked too.  one may be stuck.  all may be leaking.

 

as for the filter stuff, i did testing too.  so did canton.  they have countless thousands of these out there, a lot of them on 968s and 944s, and no issues at all.i saw oil coming back through the system FASTER with the canton than with the standard filter.  i saw plenty of air coming out with the OEM filter, but not oil.  

 

as for the oil change interval, no chance in hell.  do an oil analysis.  i do one every other change, but i did 3 of them to see how long the engine could go before needing a change, and it is nowhere near 20000km.  you'll have to show me data to prove that one, because it sure doesn't agree with mine.

 

none of this has anything to do with dan's failure though.

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[ds968]

130 K miles on my engine. ( approximately , since my odometer gears broke about a year ago and I never got around to fixing it yet, just bought the gears but they've been sitting in the glove compartment ..). However, it should be noted that about 40 K miles ago much of the engine was rebuilt / replaced , at least the top end was. And the flex plate on the trannie, among other things ..that's why it looks so good.

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[vliegwielolaf1234]

this is why i wanted the valves checked too.  one may be stuck.  all may be leaking.

 

as for the filter stuff, i did testing too.  so did canton.  they have countless thousands of these out there, a lot of them on 968s and 944s, and no issues at all.i saw oil coming back through the system FASTER with the canton than with the standard filter.  i saw plenty of air coming out with the OEM filter, but not oil.  

 

as for the oil change interval, no chance in hell.  do an oil analysis.  i do one every other change, but i did 3 of them to see how long the engine could go before needing a change, and it is nowhere near 20000km.  you'll have to show me data to prove that one, because it sure doesn't agree with mine.

 

none of this has anything to do with dan's failure though.

The porsche FACTORY recommands the oil change for the 968 at 20000km .


Not something i made up , apperantly they are a bunch of idiots there in germany .


Nothing personal , read the manual .


Sorry to mess up your topic Dan , good luck with gettimg you car back on the road , with sc it,s a lot of fun .

Would be intrested to see the insides of the engine one day

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[flash]

yeah - and they said the belt life was 60k miles too, but we all know better than that

 

manual or no manual, the reality is that the oil is too dirty long before that.  test it.  you'll see i'm right.

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[PorscheG96]

With the oil in the intake, I would look at refurbishing that head before reusing it since you will have it off. What is the mileage on this motor?

Pretty sure that blowby pressurized the crankcase and sent oil through aos to the intake, sc and MAF. It was a smoking gun in hindsight and there's no way a leaky valve guide would do that. The head was already rebuilt but we can check to receipts for details.

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[banditsc]

If the head was rebuilt then you should be good,

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[ds968]

I'll check to see if the records indicate exactly what was rebuilt - I know the head gasket was changed, and the entire variocam assembly replaced so I can't imagine they would do all that without taking care of the valves, the lifters , the guides , etc, while in there but since I've owned the car these liters have always been a bit too noisy on morning starts and until the car warms up , so now I'm not so sure how much work was done ..the maintenance records are really not very detailed and a lot of it is just what the PO said was done, he's a stand up guy , actually ended up working for my company before I agreed to buy the car so I trust he has been very straight forward about it ( particularly since I'm a sr. exec. there so not wise to mess with me, lol . )

The oil change and other preventive maintenance intervals ( belts, etc ) are subject to much debate and there is not nearly sufficient empirical evidence to support either position - only anecdotal data such as " I know of this failure, and I heard of that failure " and theoretically wha may lose its effectiveness and when , but that's really a subject for another thread , not this one .. And I'll be the first to chime in on that topic , one where Flash ( or Jay ) and I , as well as my mechanic are often at diametrically opposed ends of the spectrum, but again, it's not for this thread where we are trying to resolve the mystery of just what tne heck happened here and ruined my Christmas ,.not that I celebrate Christmas , though that's also a topic which belongs eslewhere, lol.

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[flash]

that's exactly why i say to have the oil tested.  that will tell you how YOUR engine is doing, and what YOUR interval should be.

 

that being said, i have yet to see ANY 968 go much more than 5k miles without getting very close to needing a change, and definitely needing it at 7k.  this is easily seen with a paper towel too.  if you see a dark ring around the oil when you swipe the dipstick on the paper towel, it's getting close to time to change it.  if you look at the dipstick and it's not yellow (assuming you're using yellow oil to begin with) then it's time to change it.  if it's dark on the dipstick, or on the paper towel, you waited WAY too long.

 

dirt and contaminants reduce the ability of the polymers in a multi-viscosity oil to expand.  that means that your 10-40 oil becomes 10-30 when it gets a little dirty, and 10-20 when it gets really dirty.  think about that the next time you decide to hit 6k rpm on your 10k mile oil.

 

by the way, porsche feels that 15k miles is one year of driving, and they substitute 1 year for service intervals of 15k, so it's 15k or 1 year, whichever comes first.  also, they presume that 15k means mostly highway driving, which introduces less contaminants into the oil than stop and start driving, or weekend hotdogging while the car otherwise sits.

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[ds968]

Back to the failure at hand ; the other thing I'm wondering is how does a 1 cm piece of a curved metal ring go through the cylinder ( I assume there is no way near that kind of space / tolerance ) without completely carving a trail into the walls and not seizing the position in place ? Or there is enough clearance during some points of the piston travel to let that piece slide down, but that's just insane when I think about it .

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[MCL968]

If it comes out in one pass then there might be very little damage. In my experience with these things, the odds are the block will (if you are very lucky) just need boring. What usually happens is the block gets a lot of taper from use and wear, the rings crystalize and crack from the constant expanding (at the bottom of the stroke) and contracting (at the top of the stroke).

 

If they crack into small enough pieces, they can turn sideways and blow out the bottom of the cylinder with the aid of the combustion gasses. I know if seems impossible, but at 6000 RPM, a piston is travelling its full stroke 100 times a second, and pieces like that bit of oil ring can fit between the piston and the block because the cylinder is worn and the tolerances have increased.

 

Still, I think you need to ask why the engine is seized. Rod failure seems most likely, where on the rod is what I am curious about. If you lost a rod cap, then pretty much everything below the head gasket is toast, but if you lost oil and the main/rod bearings seized, the crank and block might still be useful.

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[Bulti]

I assume the tip has the new style rods? With all the extra hp and torque of the SC and all...

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[ds968]

It's a ' 94 ( and pretty sure it's the late 94 , IIRC ) so yes, it should have the newer style rods .

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[Rap]

You will feel much better once the new engine is in. I was intent on understand what happened etc when I blew mine. Once the new one was in and the car was running and at its next event, I never looked back. The sickening feeling in my stomach was replaced with the joy of gladness and with the lightness of my wallet.

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[ds968]

No doubts about that, but it may be helpful to know the cause of this engine's demise, nonetheless. Not sure if my driving habits accelerated ( no pun intended ) the wear and tear of any given component . I have put about 70kmi on the other 968 ( bought it when it had nearly 60k mi on it ) and I have rarely kept the rpm below 4K through that entire time - that was in fact the absolute minimum even when in cruise control on the highway for long trips. so most of the time the car was driven between 5K and 6.5k , and often at redline when shifting. I just like the sound and feel of this engine at those levels . Anyway, without the timing belt failure ( to which I believe I may have contributed somewhat by revving the hell out of it like that for nearly 7 years ) that engine performed flawlessly and stil does to this very day, without a single sign of anyroblems..,but who knows if it may be ticking time bomb ?! I imagine constant high revs can't be healthy for any engine. Now, as far as the tip 968 is concerned, I drive it at far lower RPMs, just because of the nature of the transmission, as I keep it in D almost always . Yes I stomp on it a few times a day and it takes it to the redline, but it's not nearly as frequently as I did with the manual car. And the SCs only expedite how fast the car gets to the redline or any point before that for that matter, but since it does not make it rev any more that it's capable of, I would tend to think that factor makes little of no difference to anything like piston wear, rings, rods, etc. However, maybe the additional heat generated by the SC does ? I don't know.. just want to figure out if I should change my driving habits to help prevent ( or delay ) another catastrophic failure like this one . .?

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[Grandpa#3]

Hi Dan, If the engine is seized please let me know how you managed to remove all the flywheel bolts. With a seized motor I can not think of a way to reach thru the starter hole to remove all the bolts. The torque tube has to be disconnected in order to pull the engine and the torque tube collar turned to loosen the two bolts.

Cheers,
Larry

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[flash]

oof - hadn't thought about what would be involved there.  this is a tip, so i think the trans may have to come out to pull the engine.

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[ds968]

Well, as luck would have it ( AGAIN, Trevor to the rescue.. ) considering he converted his tip to a manual not too long ago, if anybody can disconnect and reconnect a transmission....lol.

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[unknown4u]

If you can not disconnect the tube you can dismantle the engine. Remove head pistons etc. Than you can probably turn the crank. Than you dont have to dismantle the tip...
The engine can be out the bay a lot quicker too.
Somehow you have to dismantle the engine anyway to investigate the ravage. Better do it now so you have not to do some wrestling with the bolt from the tube.

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[ds968]

Trevor stopped by briefly with the boroscope to see if we can look inside the cylinders - no luck ; neither the tip of the boroscope, nor the miniature mirror ( you can't see anything much with something that small anyway ) fit through the plug holes to allow a decent view of anything .. But something entirely different was " tested " and measured while in there : tne positioning of the pistons which could indicate if we have a broken or a bent rod. No such thing - the 1&4 and 2&3 are in precise synch so extremely unlikely anything is wrong with the rods. And the mystery as to what seized the engine ( bearings ? ) goes on....

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