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991.1 Bore Scoring

 
Old 04-17-2019, 04:36 PM
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Tampa991
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Default 991.1 Bore Scoring

Has anyone heard of any cases of bore scoring on the 991 engine? Dropping off my car with my indy for the change over valve job, we were talking about the 997 and 991. He said he had a couple cases of bore scoring in 991's in his shop.
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Old 04-17-2019, 05:49 PM
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Yes, I had it in cylinder #4 at about 18K miles. Started as a faint ticking sound, like a dry lifter. Dealer said keep driving it. After a few thousand miles, it got louder and started consuming oil at a rate of >6qts every 10k miles!!

Dealer finally pulled the spark plugs and #4 was black and wet with oil. Borescope showed significant scoring in just that cylinder.

I ended up getting a completely new engine at 23k miles. Completely covered by CPO warranty. Whew!

Dan
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Old 04-17-2019, 05:50 PM
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BTW, mine is a 2013 C4S with PDK. Always driven pretty gently. Tracked once for a total of about 40min.

Dan
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Old 04-17-2019, 05:54 PM
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Does anyone know if this bore scoring stuff has been fixed for good atleast in 991.2 ? (all that alisul/nikasil and what not).
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Old 04-17-2019, 07:10 PM
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Originally Posted by dolsen View Post
Yes, I had it in cylinder #4 at about 18K miles. Started as a faint ticking sound, like a dry lifter. Dealer said keep driving it. After a few thousand miles, it got louder and started consuming oil at a rate of >6qts every 10k miles!!

Dealer finally pulled the spark plugs and #4 was black and wet with oil. Borescope showed significant scoring in just that cylinder.

I ended up getting a completely new engine at 23k miles. Completely covered by CPO warranty. Whew!

Dan
When was the ticking sound most apparent?
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Old 04-17-2019, 07:38 PM
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RobC4sX51
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I have not heard anything about the 9A1 engine and bore scoring. Charles Navarro hasnít seen it either according to Panorama, March issue, page 90! Do you have pictures of the plug or a bore scope to share?
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Old 04-17-2019, 08:58 PM
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Tampa991 - ticking was apparent at idle and gentle initial acceleration. Above about 2300rpm it couldn't be heard.

Dan
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Old 04-17-2019, 10:55 PM
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Originally Posted by gulshan View Post
Does anyone know if this bore scoring stuff has been fixed for good atleast in 991.2 ? (all that alisul/nikasil and what not).
Alisul/Nikasil hasn't been used in quite some time - 9A1 have cast-iron bore liners, 9A2 is Rotating Single-Wire" (RSW) iron coated lining, which I have read is like 3-D printing on the cylinder head and supposed to be very robust.

sean
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Old 04-17-2019, 11:48 PM
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9A1 uses Alusil bore lining per Flat-6 and many other sources. I had slight bore scoring confirmed on my 997.2 (9A1) that consumed about 1liter every 1500 miles. Just did UOAs to stay on top of wear and aluminum content to make sure it wasnít getting any worse and kept topping up until I traded in for 991.2. Drove it like that for 5 years.

https://rennlist.com/forums/997-foru...l#post14570999
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Old 04-17-2019, 11:56 PM
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Originally Posted by RobC4sX51 View Post
I have not heard anything about the 9A1 engine and bore scoring. Charles Navarro hasnít seen it either according to Panorama, March issue, page 90! Do you have pictures of the plug or a bore scope to share?
It exist. Not as bad Iíd say as M96/97 but Iíve talked to more than one or two thatís tore into 9A1s. Hereís a good read - https://rennlist.com/forums/997-foru...l#post14573451
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Old 04-18-2019, 12:43 AM
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Originally Posted by Mr_Skull View Post
9A1 uses Alusil bore lining per Flat-6 and many other sources. I had slight bore scoring confirmed on my 997.2 (9A1) that consumed about 1liter every 1500 miles. Just did UOAs to stay on top of wear and aluminum content to make sure it wasnít getting any worse and kept topping up until I traded in for 991.2. Drove it like that for 5 years.

https://rennlist.com/forums/997-foru...l#post14570999
I stand corrected. I thought Porsche had made the change after the M96/97 Series.
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Old 04-18-2019, 01:59 PM
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Originally Posted by Mr_Skull View Post
It exist. Not as bad Iíd say as M96/97 but Iíve talked to more than one or two thatís tore into 9A1s. Hereís a good read - https://rennlist.com/forums/997-foru...l#post14573451
Here are some photos from when they discovered the scoring in my 2013 991 C4S. I also have to correct myself, it was cylinder #1, not #4. You will see attached a spark plug from #1 (very black) and #2 (clean). There is also a photo from the borescope showing the scoring in #1.

Dan


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Old 04-18-2019, 04:45 PM
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Here is a 9A1 from a 997.2...still havent heard many cases of the 991.1 though..likely because we haven't had enough miles build up in this generation.

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Old 04-19-2019, 04:13 AM
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Must be a rare issue in the 991 platform. I had my spark plugs changed at 33k miles on my 2013 991 3.4 and they were clean as a whistle.
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Old 04-19-2019, 02:36 PM
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Wow, it just amazes me, Honda and Toyota can build pretty much bullet proof motors but we have these crazy odd issues with just about every generation of 911. Okay before pounding, yeah I know these are high performance cars, and I am a 911 fanboy, but still, at this point you would figure they could get past these crazy things like PDK bombs, IMS/RMS, bore scoring. Now with that said, my 911 is going nowhere.

Last edited by titan7; 04-19-2019 at 04:27 PM.
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