997.2 Engine Reliability
06-12-2014, 10:13 AM
#91
Former Vendor
Just because you haven't read about it doesn't mean much… We've been tackling DFI 9a1 issues since 2010.
The first two photos are from an engine with 14K miles, the intake ports had material build up .060" (1.5mm) uniformly inside them and the valve guides were shot.
The second pair of photos are from a 9a1 DFI engine with 4,165 miles since new. It never saw its first oil change and never went to the track. Worn cylinders and broken piston rings were found when we pulled the engine apart to be built into our 4.2 X engine. We wondered why it was 27HP low on the dyno, as soon as I broke into it I figured it out pretty quickly.
Just like the M96/M97 engine, no one else is going inside these at the present time (other than my group) and because of that issues are being swept under the rug. With only the oldest of cars outside of warranty, the 9a1 is still immature enough to be unknown (to most).
Time will reveal more. In 2015 I start Instructing the first DFI engine class through Worldpac Training Institute, and technicians will start to learn a little bit of what we already know.
The first two photos are from an engine with 14K miles, the intake ports had material build up .060" (1.5mm) uniformly inside them and the valve guides were shot.
The second pair of photos are from a 9a1 DFI engine with 4,165 miles since new. It never saw its first oil change and never went to the track. Worn cylinders and broken piston rings were found when we pulled the engine apart to be built into our 4.2 X engine. We wondered why it was 27HP low on the dyno, as soon as I broke into it I figured it out pretty quickly.
Just like the M96/M97 engine, no one else is going inside these at the present time (other than my group) and because of that issues are being swept under the rug. With only the oldest of cars outside of warranty, the 9a1 is still immature enough to be unknown (to most).
Time will reveal more. In 2015 I start Instructing the first DFI engine class through Worldpac Training Institute, and technicians will start to learn a little bit of what we already know.
06-12-2014, 03:25 PM
#92
Rennlist Member
What is the main cause of bore scoring. It makes no sense for these cars with such low miles to have these problems.
06-12-2014, 03:59 PM
#93
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Jake, will bore scoring reveal itself on a consistent process of doing UOAs? Thank you!
06-12-2014, 04:08 PM
#94
Former Vendor
The fact his that low mileage engines are WORSE in regard to this failure, because the cylinders are not worn yet! The tighter the running clearances, the more susceptible the engine is to these particular failures. Being worn and loosened up is one way that most engines dodge the bullet when operated in cold climates.
Jake, will bore scoring reveal itself on a consistent process of doing UOAs? Thank you!
06-12-2014, 04:22 PM
#95
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06-12-2014, 04:49 PM
#96
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UOA = oil analysis?
06-12-2014, 04:52 PM
#97
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What are the signs of having cylinder bore score? Can it be detected without tearing down the engine? Thank you.
06-12-2014, 05:22 PM
#98
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To answer this one....
A variety of symptoms, sometimes nothing, sometimes a ticking sound, sometimes oil consumption along with ticking sound.
Supposedly, you can use a borescope to see if the cyclinders are scored; however, there is a caveat! You can't really tell how deep the scoring is with it. So, if it's showing no signs like I described above, but the borescore shows to have some scoring, you could be OK.
There was a thread with the title, "Does all of our engines have some borescoring". or something like that.
Anyway, I thought I would answer so you wouldn't be hanging!.
Mike
06-12-2014, 06:40 PM
#99
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It will take my multi- page article to finally make people understand the dynamics of this failure.
The fact his that low mileage engines are WORSE in regard to this failure, because the cylinders are not worn yet! The tighter the running clearances, the more susceptible the engine is to these particular failures. Being worn and loosened up is one way that most engines dodge the bullet when operated in cold climates.
No. By the time any wear metals show up the process is too far along. On top of that, standard UPA is not a particulate test, so the larger pieces of debris that often come from cylinders are too large to be detected by standard UOA.
The fact his that low mileage engines are WORSE in regard to this failure, because the cylinders are not worn yet! The tighter the running clearances, the more susceptible the engine is to these particular failures. Being worn and loosened up is one way that most engines dodge the bullet when operated in cold climates.
No. By the time any wear metals show up the process is too far along. On top of that, standard UPA is not a particulate test, so the larger pieces of debris that often come from cylinders are too large to be detected by standard UOA.
06-12-2014, 06:58 PM
#100
Rennlist Member
Thank you for the response. Correct me if I'm wrong, but I heard is normal for our cars to consume oil. Also, the flight 6 engines make all sort of noises to include some ticking sound.
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06-12-2014, 08:30 PM
#101
It will take my multi- page article to finally make people understand the dynamics of this failure.
The fact his that low mileage engines are WORSE in regard to this failure, because the cylinders are not worn yet! The tighter the running clearances, the more susceptible the engine is to these particular failures. Being worn and loosened up is one way that most engines dodge the bullet when operated in cold climates.
No. By the time any wear metals show up the process is too far along. On top of that, standard UPA is not a particulate test, so the larger pieces of debris that often come from cylinders are too large to be detected by standard UOA.
The fact his that low mileage engines are WORSE in regard to this failure, because the cylinders are not worn yet! The tighter the running clearances, the more susceptible the engine is to these particular failures. Being worn and loosened up is one way that most engines dodge the bullet when operated in cold climates.
No. By the time any wear metals show up the process is too far along. On top of that, standard UPA is not a particulate test, so the larger pieces of debris that often come from cylinders are too large to be detected by standard UOA.
06-13-2014, 12:37 AM
#102
I believe he means low mileage engine not broken in yet and operated in very cold temps (cold-soak, cold starts), vs. a nicely broken in engine with lots of miles on it already. The former being a worse case scenario.
Don't buy your new 991 in the dead of winter in Buffalo...
Don't buy your new 991 in the dead of winter in Buffalo...
06-13-2014, 12:54 AM
#103
Rennlist Member
I believe he means low mileage engine not broken in yet and operated in very cold temps (cold-soak, cold starts), vs. a nicely broken in engine with lots of miles on it already. The former being a worse case scenario.
Don't buy your new 991 in the dead of winter in Buffalo...
Don't buy your new 991 in the dead of winter in Buffalo...
06-13-2014, 01:38 AM
#105
Former Vendor
No, not broken in. Well beyond break in, at 20-45K miles, generally.
Being alarmed saves engines. I am only sharing what we see and what we've seen explode in terms of failures in the past 4 months after one of the toughest winters on record. Most of the cars that fail are C4s? Why? Because they perform very well in the snow and ice and are often driven more than any C2 would be in those conditions.
Being alarmed saves engines. I am only sharing what we see and what we've seen explode in terms of failures in the past 4 months after one of the toughest winters on record. Most of the cars that fail are C4s? Why? Because they perform very well in the snow and ice and are often driven more than any C2 would be in those conditions.