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After changing the crankcase lines around the AOS plenum and my discovery of the hard break in the ventricular line connecting both banks of cylinders I thought it'd be a good time to change the plugs/coils as in having no service history, mixed with the chance of fouled plugs I figured FCP needed more boat money. Everything's buttoned up and having scoped all the cylinders and examined all the plugs only two things stood out; cylinder 8 was...oily (so was the plug) and cylinder six (naively assuming banks five-eight are on the driver's side) had a rust colored scratch. I don't know how to read that so I thought I'd put my findings up here since the scope was too large in diameter to go perpendicular. No cracked coils, other plugs all had a solid black perimeter with grey gaps of uniform length.
Cylinder six's 'nature doesn't build in straight lines!' Scoring. The one 'not looking so great' Cylinder 8 plug/coil. Control pair of an plug and an coil.
yeah... other than the weird scour line in cylinder six, everything was so clean that ignoring me not really knowing what I should be looking for with the boroscope, it was a nice job. if it were 20 degrees warmer and I had music, it might've been pleasant, but I didn't drop any wrenches down the front of the engine bay this time, so that was nice...I mean you get good at pulling the belly pans, but still...New plugs and coils, so that's another one of those deferred maintenance issues I don't have to worry about popping on me.
...I suppose if I wanted to do something actually useful I'd get a leakdown test run and figure out what the port on my boroscope that wasn't covered in the instruction manual does. 3.5 styled barrel plug...
2008, just ticked over 123k. Again, it was cylinder 8 only that had the funk on it. The 'control' was what ever other plug/coil pack resembled. The fact that I had serious issues with the vacuum system tied into the crankcase breather that straddles the engine (in that the little plastic T-junction was broken, I'd say since before I had the car) makes me wonder how much of a role that played in that cylinder. I'm idling speculating though without a clear read of how the crankcase breathing system works other than it's use in emissions regulation through the recapture of oil vapor, and ultimately being part of the intake air which can screw up plugs and your cat (hence upon finding that break my replacement of whatever I could easily get to followed by plugs/coils to try and right things.) It remains the giant straight scoring on the face of what I assume the cylinder head in Cylinder six that has me the most 'freaked out.'
Last edited by Davebrossi; 03-24-2021 at 03:48 PM.
Reason: better than a follow-up post.
2008, just ticked over 123k. Again, it was cylinder 8 only that had the funk on it. The 'control' was what ever other plug/coil pack resembled. The fact that I had serious issues with the vacuum system tied into the crankcase breather that straddles the engine (in that the little plastic T-junction was broken, I'd say since before I had the car) makes me wonder how much of a role that played in that cylinder. I'm idling speculating though without a clear read of how the crankcase breathing system works other than it's use in emissions regulation through the recapture of oil vapor, and ultimately being part of the intake air which can screw up plugs and your cat (hence upon finding that break my replacement of whatever I could easily get to followed by plugs/coils to try and right things.) It remains the giant straight scoring on the face of what I assume the cylinder head in Cylinder six that has me the most 'freaked out.'
Cylinder 8 is a common area for bore scoring. That is where my 2008 CTT issues manifested themselves. Do a compression check and I wouldn't be surprised that you are down 25-45+psi on #8. It is certainly not my intent to freak you out more, but you need to consider all the possibilities. Over the years, the 2008 CTT has emerged as the year that seems the most susceptible to scoring. Remember, you cannot see the scoring from above. The real damage is below the piston rings and supposedly can be seen from below, but for the life of me, I cannot see how you could inspect the cylinders from below without removing and disassembling the engine.
Well...that's not good. The 'what to do about it' section essentially is a case of 'remove car' since unlike the IMS this isn't a case of 'fix and forget.' Didn't get a report about metal shavings from the last oil change but as it wasn't me doing it, I suppose it's send sample for analysis in addition to trying to sell the Cayenne. Unfortunately for me I have a DD, this is it. Honestly given work on both Cayennes I've done in the last two years, I guess I wont be following through on my lights comfort conversion after all. Kinda committed to the seating though. I suppose the only 'good news' here is that it didn't grenade on me first.
Yeah...no good options out there really. Can't 'fix' it, couldn't stomach selling it to another person knowing what's down the road.... I mean I dislike the dealers in town almost enough, but...Heh, anyone want to buy a 3.2 out of an 88 carrera that's sat for a few years and the rusted 914 body plus all the steel that goes with it!? Ah not a happy day.
...just to reiterate; no, I will not show up with a sock puppet account of bdrossi with a great deal on an 08 CTT...
LOL. Do the investigation first before you jump to conclusions. As others have pointed out, there could be a couple of other reasons for the symptoms you have. While a compression check isn't 100% conclusive, it will sure help you get pointed in the right direction.
Also, if you take a look at the bore scoring thread, you can see if your engine build falls in the range of the potentially problematic engines.
So, funny thing there, that's the post that got me to check my engine build then order plugs/coils.
9PAAI1;
Should fall under your TSB; "Only engines with structurally honed cylinder liners are used in vehicles as of the shown engine numbers:
References:
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"
So as I'm on that list, is it structurally honed or am I .... 'structurally boned' (please allow me humor, I was going to make a joke about looking for a false mustache but I'll take inappropriate puns instead!)
I think I most certainly need to! car is due for an oil change (and intercooler drain I might add >.>) and yes it runs, but I'm in a spot where I'm going 'uerrmm.....how often do I roll the dice?' Again, I'm not going to sell it, and I keep joking about dealerships because I'm nervous and humor is how I cope. I keep hoping (and this is where my lack of engineering knowledge kicks in) that the fact that my AOS system essentially vented to atmosphere and was cracked in a dozen places might have something to do with the plug.
I think I most certainly need to! car is due for an oil change (and intercooler drain I might add >.> and yes it runs, but I'm in a spot where I'm going 'uerrmm.....how often do I roll the dice?' Again, I'm not going to sell it, and I keep joking about dealerships because I'm nervous and humor is how I cope. I keep hoping (and this is where my lack of engineering knowledge kicks in) that the fact that my AOS system essentially vented to atmosphere and was cracked in a dozen places might have something to do with the plug.
If you decide on one, and r going to be using Blackstone Labs please don't use USPS. It took over a month for them to receive my sample.
03-24-2021 | 12:55 AM
Coil/plug day and grainy Boroscope images
and yes it runs, but I'm in a spot where I'm going 'uerrmm.....how often do I roll the dice?' Again, I'm not going to sell it, and I keep joking about dealerships because I'm nervous and humor is how I cope. I keep hoping (and this is where my lack of engineering knowledge kicks in) that the fact that my AOS system essentially vented to atmosphere and was cracked in a dozen places might have something to do with the plug.