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I don't really have much useful to contribute. But I'll post a few pictures...
I drive my 996 year round. While it parks in a garage at home, it's out in the elements at the train station when I'm at work.
I had a ticking sound, coming from the top of the engine - like a lifter...
same thing here. Canadian car that spent most of its life in Toronto.
I'm fixing it myself. costs so far are in the 12k CDN range. probably spend another $5k Canadian by the time I am done. this includes the tools, jake's course and book.
listen to Jake. he isn't fear mongering anyone, he's speaking the truth
Even at $15k, I think it's a great value for a 4.0L!
Interesting the middle cylinder is not scored or was it scored on the other side hidden from the camera?
Originally Posted by AWDGuy
same thing here. Canadian car that spent most of its life in Toronto.
I'm fixing it myself. costs so far are in the 12k CDN range. probably spend another $5k Canadian by the time I am done. this includes the tools, jake's course and book.
listen to Jake. he isn't fear mongering anyone, he's speaking the truth
Jake, thanks for the photos and explanation. That's not very intuitive as I would have thought excessive oil is burnt inside the combustion chamber and create more carbon. Good to learn new things.
Since the middle cylinder should be the last one to heat up and expand, shouldn't we expect it to score more easily (by the rapid expansion of piston skirt at cold start) than the other two? Yet in AWDGuy's case, the middle cylinder is unharmed. Maybe the tapering/ovaling of the middle cylinder actually helped a bit in this case?
My understanding is the excessive piston/cylinder wall clearance allows the piston to rock causing the piston top to hit the head. In some cases, you see a shiny spot on the piston top edge where it's hitting the head.
This might be a weird question -- but why do bore scored engines make a noise that sounds like lifter tick?
Because the wear starts at the bottom of the bore, where the piston direction changeover occurs. When the issue starts the excess clearance between the cylinder and piston at BDC creates the tick. The sound has the exact same rythym and volume as a bad lifter.
As far as the center cylinder not having the issue, that's just proof that cylinder quality matters, as well as piston skirt coating quality. Lots of these failures start off with failure of the adhesion of the piston skirt wear surface (coating).
Normal wear can help avoid this, as one of the biggest issue is having too tight of cylinder clearance for cold weather contractions. The wear can increase it just enough that failure does not happen. I see most cylinder failures at less than 80k miles.
Wow, almost 170k miles! I think you got your money's worth
Yes, I have absolutely gotten my money's worth out of this car. But, now, a replacement engine is probably more than the value of the car...
Originally Posted by Ahsai
That's not very intuitive as I would have thought excessive oil is burnt inside the combustion chamber and create more carbon.
Even thought the top of the piston was clean, there was a lot of carbon on the valves - so much, in fact, that there was hardly any compression in that cylinder.
Jake, I'm still running my engine - what do you think the final failure will be? Cracked cylinder wall and coolant/oil mix? Metal in the oil causing a bearing failure?
Jake, I'm still running my engine - what do you think the final failure will be? Cracked cylinder wall and coolant/oil mix? Metal in the oil causing a bearing failure?
Please don't. Please stop driving it to death. Core components are getting so hard to find that their value has tripled in some cases.
Continuing to drive it will just make more things fail from collateral damage. The microscopic debris that's suspended in your oil is traveling to every part of the engine and delivering wear with it. It will take out everything that's internally lubed, if it's driven long enough.
Engine costing more than the car? That's every Porsche I have ever worked with that was more than 10 years old, until it becomes a classic. This is nothing new with the marque.
If you love the car, the value from reconstruction of the engine means you can go for many more years together.
75% of the cars we build engines for "are not worth" as much as the engine costs. That only stops the guy that doesn't love and appreciate the car enough...
Interesting the middle cylinder is not scored or was it scored on the other side hidden from the camera?
My understanding is the scoring only occurs on the bottom (relational to the position of the motor in the car, not piston movement) side of the cylinder.
My understanding is the scoring only occurs on the bottom (relational to the position of the motor in the car, not piston movement) side of the cylinder.
Is that correct or no?
zTop and bottom.. Where the piston skirts travel. The skirt is the largest portion of the piston, and has the tightest running clearance.
The only time it will score on the sides, is when the piston separates from failure.
That day won't come with quality items, that are truly developed, and proven.
Each year prices go UP, not down with these engines, as the cost of labor, and the cost of business creep up due to inflation.
The ONLY chance that the truly developed offerings have in becoming less costly, is if the volume goes up tremendously, and we can make larger runs of parts, which can be produced cheaper per unit.
The cheap, less than proven, half assed engines, and components may drop in price, but that'll only be due to the providers doing everything they can to stay alive.
I sat back and watched this exact same thing happen with aircooled engines, and cars. The REAL options have a big price tag, but offer value that the people who want to create some start- up company to compete with can't see, or appreciate. They start slashing prices, then they realize the amount of work that goes into it, then they have to cut quality to make a little more money, but by then they have so many engines that have failed that it takes out their reputation. Its a catch 22 then, because even if they wanted to stand behind the engines, they are so broke that they can't afford to.
The most expensive Porsche engine you'll ever own, is the cheapest one that you can buy. No one will appreciate this until they experience it. Lots of people have these days, almost 1/2 of our work today comes from the failed attempts of others, thats way different than it was in the early days, when no one else would dare touch one of these engines.
As far as the car getting older, and things becoming cheaper, well, I won't touch an aircooled Porsche flat 6 engine for less than 25K, which is more expensive than my most expensive 4.0L M96/ M97 street engine, making 420HP. Most of the aircooled engines run 30-35K, and these prices have been the same since 1999.
Hell, I charge the same to build a 4 cylinder aircooled performance 914 engine as I charge for an M96/ M97, and have a line out the door for them.
Here's what I am building today... 4.1L 964 based beast for a Beck 904 GTS
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Damn that is gona be nice, I've always wanted to do a Beck 904, with that engine is will be a load of fun but probably a bit overkill for it.
01-08-2016, 12:35 PM
