Had a “intermediate service” done last week at 58k miles paid almost $1300, parts was 250’ish while labor was north of $800 wtf? picked it up Friday and drove for a day on Sunday check engine light came on and flashes…mis fires…. Dropped it back off at dealer in North jersey… repairs needed…smh $1900 in labor for sparks…. Any recommendations on shops in north jersey?

 

Interesting. First I have seen this on this site. Mercedes has having oil-vapor separator failures on the M17x 4.0L TT V8, which causes crankcase overpressure and resultant rear main crankshaft oil seal failure.

Please keep us updated on the repair. Did you get a list of codes from the dealer?

BTW spark plug replacement isn't required if the separators are being replaced. Decline this service unless you want it.

 

Looks like dealer may be needlessly replacing the air-oil separator.

According to this TSB, the check valves in the breather lines are failing. TSB calls for ONLY the breather line replacement, followed by test drive. If the problem persists, then inspect the (expensive) air-oil separators.

From the TSB: “E3 Cayenne and G2 Panamera customers report a rough running engine, whistling noise, and/or check engine light displayed in the instrument cluster. It is found that the diaphragm in the oil breather line (crankcase vent tube) or the tube itself from either bank 1 or bank 2 can be cracked, causing this failure in the present V8 bi-Turbo engines.

If the vehicle falls under the previously stated conditions, then please replace only the breather lines shown below in Figure 2 as “5” and “10” containing this diaphragm in the check-valve assembly, first. If related issues or fault codes persist after a test drive with the new breather lines installed, check the oil air separator for damage.”

 

Wow thank you for that! I will show this to my SA once I get back in town.

Here’s the video the tech sent explaining the issues.

https://app.truvideo.com/v/mcTJSrXS?...b9pt2y7xrakBI=

 

This happened to my 2020 Turbo @ about 25K.
https://rennlist.com/forums/cayenne-...separator.html

 

Had this issue on both banks. Fixed under warranty. The service dept seemed surprised to see damage on both lines, so they probably have not seen the TSB and/or this is not a frequent issue.

 

I’ll be picking up the vehicle tomorrow… the repair is on me. $2535+ tax….

they suggested to do spark plugs (I declined) I have apr coils on it which they “couldn’t” take off so if they do they’ll break and would need to be replaced with oem coils. Overall I am NOT happy with the way this dealership handled this situation along with the outrages prices that was quoted.

 

Thanks for the update. Sorry to hear about the price tag. Did the dealer give any detailed explanation of what exactly failed on the vapor separators? Check valve or pressure relief valve internal to the separator plugged?

 

I’ll check the work order tomorrow and ask. Will keep you posted.

 

The catch cans on these cars are self-emptying right?

 

Yes, and there are internal components (check valve or pressure relief valve) that can plug and create problems. CEL and misfire as reported here, rear main crankshaft oil seal failure in the case of MB M17x engines.

 

Here’s a diagram of the air-oil separator with highlighted pressure control valve and check valve (as pointed out by chassis).

 

Perfect. I think also mentioned in this thread are valves in the lines (tubes, hoses) to and from the separators. A blockage in any of these PCV components can cause problems. While not yet reported on rennlist to my knowledge, MB owners are seeing rear main crank seal failures because of vapor separator failure.

Looks like an aftermarket opportunity to remove the OEM solution and install a traditional catch can that is drained by the user periodically.

Porsche and MB are attempting to execute a catch can, but in typical automotive fashion there are problems with these new solutions.

 

Wow that's quite an oil catch can setup....

On my GT350 it's just a plastic reservoir with a couple of hoses that I have to empty a couple times a year.

 

These separators are the type of thing I would be inclined to replace preemptively at high mileage / out of warranty. I do the same with poly-v belts, ignition coils, and top+bottom radiator hoses.

Replacing the PCV components at end of warranty is smart in my view because the system is showing itself to have problems, and is not specified as a regular maintenance item. The old take-off parts can be used as backups after cleaning with solvent.

A less costly but less sure approach would be to remove the PCV system at end of warranty and clean it with solvent. eg brake parts cleaner, engine cleaner, Simple Green, etc. Then reinstall the original parts and hope for the best.