oldskewel

And speaking of denial...

That's exactly what I expect you'll get from Porsche. This is a very well known issue. Porsche of course knows more about it than anyone here, but of course will deny that it is widespread, claiming that it is a rare situation that just gets talked up. They're lying.

Like I mentioned, my 2004 S had this problem at 45k miles. Well maintained. Happened out of the blue, causing the engine to seize.

To be as optimistic as possible, I'd advise to keep testing and see if you can rule out the scored cylinder(s) and hopefully find the problem to be something more easily repairable. But if you do find scored cylinders and can find a financially viable way out of it, please publish the solution because there will be a lot of interest in it.

Also, you should realize that everyone here, even those that you might think are overly negative, are pulling for you to get out of this problem as well as you can.

tats

95_993

I know many here are doing oil analysis like Blackstone. Has anyone here seen a spike in certain metals as an indication of scored cylinders before it reaches a point of catastrophic galling that some of the major failures depict?

Pillow

But yet continued making the same engine on Gen 1, 2, & 3??? Seems odd they would allow a grenade to keep in production that long.

Naive question comment here from a 4.8 noob...

Could the block be proactively bored over X tenths? Then use LN or JE or Keith Black pistons to spec for replacements? Add oil squirters (like in the Turbo block) to cool and lubricate the pistons from the bottom?

What is actually killing #8? Oil starvation - heat - bad ring lands? Lean #8 condition due to intake manifold design?

Sorry if this has been covered before, but it seems odd that a repair that would be "easy" for a normal American V8 would be so difficult for a Porsche...?

NelaK

Don't forget the 911 engines. They also suffer from the issue plus they also get IMS bearing failures.

I guess you could proactively fix it but I can't see how fixing it proactively would cost any less than fixing it when it breaks. Its the exact same work that's being done in either case. I guess there's a risk that when you wait for it to fail, you could have more damage but I think generally its just the cylinder walls and pistons.

Not going to comment on this since there's experts on here who could probably fill books on their research on this topic.

Few factors I think.
1) Porsche keeps the information to themselves, and the people that have reverse engineered it did so at great expense (time and money) and offer those services professionally.
2) There isn't really a huge aftermarket for this work which means there is only one supplier for most of the parts (Porsche) and a limited number of highly in demand specialists who can do it.
3) Porsche loves to use exotic materials, processes and technologies. From the factory's perspective their scale can bring their costs to be competitive but for the aftermarket everything becomes a lot harder.

deilenberger

To date - I can't recall hearing of any bore failures on the 958 series V8's. I believe Porsche may have gotten a grip on the issue around 2009 or 2010. I'm sure if there has been a failure on the 958 series it would be pretty well known by now.

deilenberger

Since not all of them actually fail (I'm guessing at this point about 10-20% - but the Internet concentrator distortion makes it seem higher - ie - people don't report ones that don't fail..) this would seem a rather expensive thing to do in order to avoid something that really isn't that likely to happen. Adding oil squirters isn't trivial (it's part of the block on the turbos) and doesn't guarantee the failure won't happen - ie - this thread illustrates that.

It's not just #8. There have been failures on #5 reported and I believe #6. The theory of failure that makes the most sense to me is the company making and machining the blocks for Porsche (there are rumors 2 companies were doing it.. dunno..) bored them on the slightly too snug side - or at least some of them. And under cold startup conditions the pistons heat quickly and the bore less quickly - meaning the pistons expand faster than the bore, reducing those clearances to less than optimal. Once scuffing starts - it probably only gets worse.

Most American V8's aren't anywhere near as complex as the Porsche V8. There are several layers to the Porsche engine that in an American V8 would be a single casting. Porsche makes up the block pretty much like a birthday cake. And they used different materials where they could optimize the engine for lightness - the V8 has a surprising amount of magnesium in it. A typical American V8 looks rather primitive compared to the Porsche V8. Perhaps primitive is actually good though..

NelaK

I recall Jack Raby mentioning in one of his posts that he had a 2011 or 2012 with scored cylinders. I think age/mileage might be a factor too. Previously the general consensus was that the 08 and 09's were much less prone to it, then it was the Turbo's were much less prone to it and yet both have been proven wrong over time. That is kind of worrying though since it could mean that potentially every Cayenne engine will eventually grenade itself.

Is it really more primitive though? Its not like there aren't American V8's that put out comparable numbers. The LS motor is smaller, has variants that put out more power, is cheaper, more reliable and better supported. Just what is Porsche's fancy technology returning in benefits?

Pillow

Good to know!

That combined with tight rings would def cause some issues!

Magnesium! Is this a 356 or early 911

I admit, I'm normally an "LS Everything" person as the LS is so easy to build and it lasts forever at 400+HP levels. Even some of the LS engines have issues though! And you are correct when a stock motor goes south people tend to complain over the other X millions of owners with zero issues.

... This is still a scary thread! LOL

tats

J'sWorld

Of course its smaller. It's half the engine of the Porsche. What's the difference? To many for you to wrap your head around. The LS can never dream of achieving the volumetric efficiency of the of the Porsche. That's just the beginning. Anybody can have the Vette or the Mustang or whatever but there are still some things that money can't easily buy. Take it from a blue collar guy, you and I both purchased used Cayenne's. Time to suck it up.

Wisconsin Joe

Most of us on here are not Porsche techs. But anyone who's been on here any length of time knows about this issue.
I have yet to hear of lifter issues. Or cam issues (other than the 958 Vario-cam, but that's different). Or anything other than bore scoring causing a pronounced ticking sound.

It will run for a bit. It will start to use more and more oil. It will start to miss as the plug in the bad hole gets fouled. It will continue to get worse. Sooner or later (not a whole lot later) it will seize.
Driving it 'just around town' may prolong the life.
A little.
Or not.

Where and how it was serviced seems to make no difference. It seems to be a manufacturing flaw.

Good luck dealing with Porsche on this. The few that I have heard of having any success in getting it covered (out of warranty) are those who have a long relationship with the dealer (the dealer has and will make enough money off the customer to eat the costs). Otherwise, they will pretty much ignore you. It took a class action lawsuit to get them to acknowledge the coolant pipe issue on the 955.

If you can find a way to get the motor rebuilt or replaced without it costing more than the car is worth, please let everyone know.

I am curious where you get that "10% - 20%" number.

Data shows that for 7 years (03 - 09), they sold 86k cars in the US.
http://carsalesbase.com/us-car-sales...rsche-cayenne/

That would be 8k to 17k failures in just the US. I can't believe it's that high.

I'm of the opinion that the failure rate is around 1%. But that's just a guess.

NelaK

I think 1% is way too low.

One user tried to locate every Cayenne owner in their area and their survey showed a failure rate close to 20-25%.
​​​​​​
https://rennlist.com/forums/cayenne-955-957-2003-2010/948215-porsche-cayenne-s-piston-cylinder-scoring-issue-statistics.html

They might live in a cold region so that's probably skewing the numbers in one direction while warmer climates skew them in the other.

Either way I think the numbers would be low single digits in warm climates, low double digits in cold climates and middle single digits overall.

I'm almost certain age is going to drive the numbers up even further too.

Wisconsin Joe

That's a sample size of either 33 or 34.
I find it hard to draw any real conclusions from a sample that small.

Also, post 4 notes that there are usually a number for sale with ticking.
But a lot, lot more with over 100k miles.

Again, I don't know.
And as I have noted before, I don't think anyone, including Porsche themselves, have an accurate figure.

oldskewel

I personally believe the rate is pretty high. I also expect Porsche now knows exactly what the source of the problem was. Probably a good business decision at the time to deny it. Remember the tough days during the global financial meltdown when they were even considering buying VW, then next thing you knew, they were trying to stay solvent. Living on the edge is not a time when they'd be likely to start owning up to their mistakes if they don't have to, even if it degrades their brand.

Also, almost every person and corporation denies fault until they can't get away with it. Just about every recall in the history of man was originally denied until the company was forced to accept responsibility. And if that point never comes, the denial continues.

From my sample size of 1:
100% scored cylinder failure rate
100% of failed engines were returned to Porsche for teardown and analysis if needed.

So that's my statistical analysis. Kidding of course about drawing a conclusion from a sample of one. There have been a few people posting on here (and that is a sample of the population of course) that have multiple failures. Just considering that, it must be much more than 1%.