jeff spahn

I don't hear piston slap. I hear injectors though, normal injectors.

garrett376

I haven't heard of a single 958 with bore scoring. Where did you come across this?

TRINITONY

'
Not very common, but here is one example and I've seen a couple others mentioned..

Updates on the engine noise. I Just came back from Porsche. They found that Cylinders 1 and 2 were unusually - very scored and these 2 cylinders became loose (!!!). They are replacing the whole engine with a brand new from Germany under warranty. What a bummer! That's crazy, car was never abused. I'll try to get pictures from them to post.

https://www.6speedonline.com/forums/...start-ups.html

Long version: the dealer did a borescope test and found unusual damage on #1 and #6 cylinder wall that cause the knocking noise on cold start. After reviewing the photo facts, PCNA agreed to replace the whole engine under manufacturer warranty. But I was disappointed as it wouldn't be a brand-new but re-manufactured.

https://www.6speedonline.com/forums/...r-porsche.html

TomF

Hi Joel,

All good questions. I have not personally seen a GTS with scoring, and to be fair, I suppose we shouldn't rush to judgement there. Many of us who have followed this issue nearly from the beginning have assumed that because the blocks are the same, and from the same one of two suppliers, that they would have equal propensity for scoring.

Additionally, there were posts here on Rennlist a while back from an engineer that was clearly associated with Porsche at some point (and who was clearly) intimately knowledgeable about the Cayenne engine supply chain) who indicated that if the engine originated from one of the suppliers, there was a much higher likelyhood of scoring. His post was very technical about cylinder honing and referenced the callibration of optical measuring equipment. I have been unable to find the posts again and suspect that they were deleted due to Porsche's litigious nature.

The TSB seems to be the best resource and predictor out there that gives an indication of the predisposition of an engine to scoring. I suspect that there is a way to tell which engines originated at the bad (and aparently cheaper) supplier but no one has been willing to share that with all of us. I would also be willing to bet that there is a list out there that shows every engine sourced from the errant supplier.

So, to sum up... the assumption has been, if the block is the same, as in the case of the S and GTS, then despite having different ancilliaries, it will have the same propensity to scoring if it has structurally honed cylinder liners.

If you have more specific engine codes or serial number ranges to share from the GTS engines that will help fill in the gaps and help with a clearer picture of what to look for, please kindly share with the rest of us.

Cheers,
Tom

Jfrahm

Porsche's docs include the specific engine number range for the 957 S and for each year of the GTS, if someone has a list of engine numbers with scoring we can correlate.
Since I do not see the GTS (Cayenne or Panamera) listed in the TSB I suppose it's possible that the GTS blocks are honed to larger clearances, as one might, to accommodate higher output. Or they all got the updated honing (I assume the "hone the hell out of it, please") process. Interesting that someone other than Kolbenschmidt might be casting some of these blocks, presumably licensing the technology. Any idea who?

https://www.porsche.com/filestore.as...letype=default

Cheers,
-Joel.

europorsche914

I am still not convinced that the structurally honed cylinders apply to our models unless you have a replacement engine. The starting engine model falls in the 958 series of the Cayenne M48.02/48.52. The TI is attached.

https://static.nhtsa.gov/odi/tsbs/20...73034-0001.pdf

TomF

Hi Joel,

Thanks for your thoughts on this and the updated V-list. My older version of the V-list did not include the engine codes and dates of production so this is extremely helpful. If one references the original TSB from 2013, the GTS engine codes are included in the list of structurally honed blocks. The codes are: 9PAAL1 for the tiptronic and 9PAAL7 for the 6 speed manual. My 2009 CTTS engine is listed as well.

Here is the list from the original 2013 TSB:

"Only engines with structurally honed cylinder liners are used in vehicles as of the shown engine numbers:92AAH1, 92AAI1, 92AAL1, 970110, 970111, 970120, 970121, 970410, 970411, 970420, 970421, 970430, 970431, 970440, 970441, 970450, 970451, 9PAAH1, 9PAAH7, 9PAAI1, 9PAAL1, 9PAAL7, 9PAAN1, 9PAAS1

Model year as of 2008"

Note that the new TSB from Mar 6, 2020 posted above is referencing the later 958 and Pano models. It is interesting that they do not note the actual engine numbers in this TSB.

I will dig deeper again into the data. Often as time passes, information slips through in revisions of TSBs or parts catalogues that is very helpful. I have a suspicion that there is more to be discerned from some of the recent documents.

TomF

This is incorrect, but the TSB is very useful- Thanks for posting it. See my comments above.

europorsche914

I see that it has been updated as of March last year. Do you have a copy of the original?

TomF

I wish I did. I was only able to capture the text of the TSB that was posted before. It was pulled almost instantaniously, and I am assuming because of the litigious nature of Porsche, almost immediately.
Also see: https://rennlist.com/forums/cayenne-...assifieds.html

Here is the text I copied:

"Engine - Crankcase/Piston/Piston Ring Replacement Info.
Service 1 25/13 ENU 1010 Jun 20, 2014The present document was valid at the time of print. A later version may be available online

Crankcase/Pistons/Piston Rings Need To Be Replaced - Mixed Installation Is Not Approved (25/13)

Model year:

as of 2008

Revision:

This bulletin replaces bulletin Group 1, # 25/13, dated June 11, 2013. Section "Information - Spare Parts Requirements" for pistons and piston rings: Text changed to "now available again".

Vehicle Type:

Cayenne S (9PA)/Cayenne Turbo (9PA)/Cayenne Turbo S (9PA)

Cayenne S (92A)/Cayenne Turbo (92A)

Panamera/Panamera S/Panamera Turbo/Panamera Turbo S

Concerns:

Cylinder liner in crankcase

Information:

If piston rings/pistons or the crankcase need to be replaced, a mixed installation can damage the cylinder liner.

NOTICE

Combination of piston rings and crankcase.

^ Risk of damage to cylinder liner.

--> Observe specifications for permissible combinations.

Due to

^ modified production methods during the manufacture of the crankcase --> from smooth honing to structural honing

^ and the use of a different coating on the piston rings (now DLC-coated)

only the combinations specified below are permitted.
--> Before carrying out any other work, check whether the cylinder liners are smooth-honed or structurally honed:
Date of Introduction:
Only engines with structurally honed cylinder liners are used in vehicles as of the shown engine numbers:
References:
--> 101055 Replacing crankcase
--> 131020 Removing and installing pistons
--> 131037 Disassembling and assembling pistons
92AAH1, 92AAI1, 92AAL1, 970110, 970111, 970120, 970121, 970410, 970411, 970420, 970421, 970430, 970431, 970440, 970441, 970450, 970451, 9PAAH1, 9PAAH7, 9PAAI1, 9PAAL1, 9PAAL7, 9PAAN1, 9PAAS1Model year as of 2008
C02, C36

There you go. I am digging through a mountain of data that I just came across yesterday and hope to have a more definitive answer to the question of which engines to avoid.

Cheers,
Tom

Libast

From NHTSA

June 20, 2014 MANUFACTURER COMMUNICATION NUMBER: 122-J3Z8Q-06
Components: ENGINE AND ENGINE COOLINGNHTSA ID Number: 10117453

Manufacturer Communication Number: 122-J3Z8Q-06

Summary

Concerns: Cylinder liner in crankcase

Information: If piston rings/pistons or the crankcase need to be replaced, a mixed installation can damage

the cylinder liner.
3 Affected Products

Vehicles

MAKE MODEL YEAR
PORSCHE CAYENNE S 2008 PORSCHE CAYENNE TURBO 2008 PORSCHE CAYENNE TURBO S 2008



EDIT - Europorsche beat me to it

TomF

The links don't work for me... edit. I was able to search for the document.

From what you posted, the TSB is from 2014... which is newer than the one I copied from. Strange, there are no engine codes listed in the 2014 version.

Libast

Yeah I just copy pasted. The thing is it only lists 2008 model years which I think is the more telling factoid.

Jfrahm

Can you tell with a borescope if an engine bore has smooth or "structural" honing? I've had a bunch of Alusil engines and all the bores I have seen have been glassy smooth. The final "hone" is with a caustic paste to dissolve back the aluminum and expose silicon. The block alloy material has a high silicon content.

Charles Navarro

We have a Panamera block here someone abandoned after it scored and we've had two Macan calls this month.

The problem I see with these cars is that they are just an appliance. People aren't going to spend the $15-20k min to correct a cylinder deficiency in these models. The only ones we mostly ever fix are GTS and Turbo Cayennes, almost exclusively from Canada.