westy66

hey jake, I am in ohio.I'm quite familiar with your work as I've been driving volkswagen buses for over 15 years. I just got the Cayenne in July and This past winter it sat in the driveway because my bus is in the garage. There were 2 or 3 mornings where it was at least 10 below zero.

when the service manager called to tell me the news I immediately thought that that may have been the case

Doug_B_928

-10F is only -23C. For us, that is normal in the winter (we can get as cold as -50C). I know that Jake has determined that the cold precipitates this condition, but there must be some intervening variable or else every engine submitted to these temperatures would fail. If Jake or someone with his level of knowledge of these engines could identify the variables (e.g., oil specs, how long since oil change, how long since previous start, how often exposed to cold temperatures, how cold, etc.), then a thread could be started where victims of cylinder scoring could contribute so that a data base of sorts could be compiled and perhaps shed some further light on this (much like the IMS thread). It increasingly looks like this is the next IMS-like saga.

DWPC

I'm kinda curious what oil brand and weight was in the scored CTT engines.

chubalua

Does High RPM at cold in the morning precipitate the problem?

Flat6 Innovations

Oil has little to do with this. It's a clearance issue that's related to temperature.

This hard winter will keep us slammed for many months to come, or even years. The Canadian work has already started coming in.

dryadsdad

I'm guessing then, the lesson is not to use our machines when the temps fall very low. Is there some sort of threshold you've found where it's best not to use them below?

Flat6 Innovations

I continue to study these occurrences and have a large freezer that I am using to measure component clearances at different temperatures. I want to include the data in my Cayenne engine classes coming up later this year.

I haven't found the exact temperature threshold as of yet but we are on to something now.

The other odd issue that's not really that odd is the engines with higher mileage have less occurrences of this issue. Component wear becomes a good thing (to a point) because it adds just enough clearance that the issue is less likely to occur.

More later, I am working on a new lab building and won't be able to finish my study for a few more months once I get all moved in.

dryadsdad

Thanks. Please keep us informed of your findings.

westy66

what about a block heater? I see that porsche never designed one, but there are a few aftermarket options out there. It seems I'd have to come up with something after a rebuild, no?

CaptJim

https://www.wolverineheater.com/Engi...ars-s/1814.htm

westy66

thanks Capt... thats what i was looking for. i knew there was some sort of adhesive one. is the CTT oil pan flat or finned tho?

mtnrat

There is a flat spot, but it is not very big. You can just fit a 2 1/4" x 4" pad on it. I used one by proheat. Model 154, 125 watts. It is really only rated to heat up to 4 quarts of oil, but is all that will fit. Any air gaps with result in fire.

westy66

just found out from my service manager that with my new shortblock, there is indeed some changes that have been made by Porsche.

"As of 2008 Cayenne S / Cayenne turbo:

modified production methods*during the manufacture of the crankcase ⇒ fromsmooth honing to structural honingand the use of a*different coating on the piston rings*(now DLC-coated)

Doug_B_928

So, is your service manager implying that with these changes cylinder scoring should not be a problem on the 08 and new S's and turbos?

Flat6 Innovations

But the problems are not associated with piston rings or the roughness average of the cylinders. I can see how a DLC ring is beneficial, and the associated cylinder changes are necessary for this ring to seal, but if cylinder/ piston clearance was not altered the issues will not be solved.

Remember, the wear that we see is always starting BELOW the point of the cylinder where the piston rings travel.