firewire

Mungojerie, you have a problem that is shared by many Cayenne owners. Older Cayennes especially the ones in Northern climates have a problem with scoring cylinders and blown engines, faulty coil packs among other issues. I bought a 2004 Cayenne S with a bad engine, and I naively thought I could rebuild the engine. After buying the low mileage excellent condition Cayenne I found the engines are not easily rebuilt like a "normal" vehicle. Getting a replacement engine was the best option however few are available and at high prices. The dealer. quoted me $12,000, and then $20,000 to replace the engine. The engines can be rebuilt but require special knowledge, skills and equipment, so was not an option for me.
The coil packs have been redesigned several times but at last viewing a few years ago they had not successfully fixed the defect (they may have done this by now). Coil packs were replaced under warranty, but continued to cause problems. The REAL PROBLEM is that the coating on the cylinders supplied by a third party was the wrong formula, and Porsche just figured this out a few years ago. They have not admitted this as it represents a huge liability for the most profitable car company in the world, and I have never seen this mentioned in any forums. This does not seem to have caused the same degree of problem in warm climates as in cold climates, and most of the engine problems show up in Northern cars with scoring of cylinders, ticking noises, and made worse by misfiring caused by malfunctioning coil packs. Given this problem any salvage engines have the same design issues, and are suspect. From my experience I would recommend trying to recoup as much as you can and get rid of the Cayenne. Don't let this turn you off Porsches, as they are usually a well engineered car and great fun when they work well.

Hatmando

I'm curious about this statement. I own a '08 GTS with a V8 and 125,000 miles. It has spent it's whole life in WI or MN - certainly cool here. Other than replacing the coil pack I've not has a single ignition problem or major engine issue. I've also owned a few V8 Audis and ran them past 100K without any issues. What is the reason for the cold weather concern? I would think the Germans know something about cold weather and their engineers are certainly talented enough to resolve a climate issue.

Just looking for more information on what to look out for.

oldskewel

It is a very specific, but fatal problem. Next time you have a few days of free time for reading, search on here for "cylinder scoring." It is an engine problem that usually totals the vehicle. It has been reported to be more common in cars in cold climates, but my 2004 S has always lived in mild California and did have that problem at about 50k miles (luckily early enough that dealer+Porsche assistance allowed it to be cost effectively repaired).

Hatmando

Thanks for the info oldskewel. It looks like I'll have to do some research. Strange how it seems so random.

hopsis

In my understanding bore scoring is a combination of

1. Cold climate (more need for fuel enrichment because more cold starts)
2. Fuel type (not much that can be done there, other than moving)
3. Wrong type of use, mainly warming up the car by idling the engine until interior is warm and ice/snow melted from windows.
4. N/A engine

Cold starts require more fuel, that extra fuel will not burn perfectly, instead it will act like a solvent and clean the oil film from cylinder walls. Then there is the matter of warming the car by letting it sit at idle for half an hour on the yard. Even the owners manual states that You shouldn't do that, You should start the engine and drive away immediately. This is because the engine warms up much more slowly when idling with no load, so the period of injecting extra fuel is longer. Turbos don't suffer from scoring as much because there are oil sprayer jets under every piston lubricating the cylinder walls and pistons all the time. N/A V8 engines do not have these.

I'm thinking at least 3 of those 4 things have to come together to create problems and would explain why some engines have bore scoring even when they've never seen real cold starts. But if You thing of it by terms of normal engine operating temperature, every start is a cold start, even on a hot California day. Maybe users like to cool their cars with aircon before leaving and the same idling period is there?

This all is a really simplified way of looking at it though and most importantly of all, it's nothing scientific, just my understanding of the chain of events. It's probably still a bit random.

Wisconsin Joe

Hopsis has a pretty good summary.

To add a bit:

It is pretty random. Nobody seems to know how many cars are affected. Not even PCNA. Most of the cars that get it are out of warranty when it happens, so the factory/dealer often isn't involved.
Don't forget that the factory has ignored/denied issues on a variety of issues with several different models. It took a class-action lawsuit to get them to admit there was a problem with the cooling pipes in the 955. My faith in 'German Engineering' isn't what it used to be.
There are a couple sticky threads worth reading.

Cold climate seems to be an issue because the aluminum block & iron pistons expand at different rates. Or it might be the extra fuel washing the cylinder walls clean. Again, nobody really knows the exact mechanism. There's some excellent speculation (some of it well informed speculation), but very few actual facts.

I have one that spent it's entire life in WI, and am at 126k miles. No issues yet.

It seems to occur mostly between 60k - 90k miles. Not exclusively, but since you made it to 125k, you stand a good chance of being ok, even with a N/A motor.

For the 4.5L in the 955, it happens more in the N/A motor than the turbo.

jeff spahn

I would agree with Wisconsin Joe. I sold my last Cayenne (05 S) with over 220,000 on it and it ran beautifully. Lived its entire life in either MN or Iowa, both cold climates. In both cases, the car was not let to sit and idle to warm up. Either lived in a heated garage or when left outside was started and driven. My only datapoint on a N/A Cayenne as my new one is Turbo.

deilenberger

Welcome to the forum - I see you're fairly new here and you might not know about some of the sources we provide members:

There are two places where you can find the information you seek - one is the sticky at the top of the page "IF YOU'RE THINKING OF BUYING A 955/957 (2003-2010) - READ THIS FIRST!" and the other is the "New Bore Scoring Survey 955/957, 2003-2010"

The survey is rather detailed - and includes information on the frequency/year-model, normally-aspirated vs turbo, cold area vs other. You'll find the facts do not support some of the statements I've read above in this thread.

Have fun!

PS: We also have an EXTENSIVE DIY section - the first place to look if you want to attack one of the common jobs these beasties need.