ML350 M276 Timing Faults - Repair options

Alexander Owner/Technician Pennsylvania Posted   Latest  
Resolved
Driveability
2012 Mercedes-Benz ML350 4Matic 3.5L (276.955 Flex) 7-spd (722.9) — 4JGDA5HB9CA056143
P054C — Cold Start "B" Camshaft Position Timing Over-Advanced Bank 2
P054A — Cold Start "B" Camshaft Position Timing Over-Advanced Bank 1
P0019-85
Extended Crank/Start

Vehicle came in with check engine light on and extended crank. Verified extended crank, checked faults. Clear faults, engine started quicker but P001985 returned immediately. 

Scoped cam timing and timing is off. Removed cam sensors to check reluctor wheels at 53degrees. Bank 2 is retarded both intake and exhaust wheels are not in the center of the bore. Bank 1 reluctor wheels are in the center of the bore. 

Got approval to remove bank 2 cam cover. Found cylinder 2 intake lobe pitted, rocker roller worn also. Both cam actuators/ gears look to stay locked and not move independently when turning engine over by hand. 

After looking at repair info, is it recommended to just replace the chain with master link or should the cartridge assembly be replaced. From what I can see the rails look ok. Also if cartridge replacement is recommended can it be replaced by just pulling lower timing cover or is cylinder head removal required? I also have concern about the intermediate sprocket condition. 

Also pricing a used engine for the customer vs repair. Can you use a new year engine? 2014? There are a 2 local to me with 50K for less money than a used 2012 with 75K. Not very knowledgeable on Mercedes, any help is greatly appreciated. 

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Edward Instructor
Florida
Edward
 

Bank 1 has cylinders 1,2,3 and is the bank on the right side with you sitting in the vehicle. Bank 2 has 4,5,6 and is on the left hand side. How far off are the marks at 53 degrees? Did this engine have a cold start rattle? Keep in mind on these engine the cam phasers don’t stay locked and move when the engine is cold one way to tell is to see if they squirt oil when turning the engine over…

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Alexander Owner/Technician
Pennsylvania
Alexander
   

No rattle noise, even on cold starts, does not have updates tensioners or check valves installed. 1st photo 53 ATDC the in order b1 exhaust reluctor, b1 intake reluctor, b2 intake reluctor, b2 exhaust reluctor, 40 ATDC marks on back of cam. My main question is can a used 2014 m276.955 engine be used in a 2012?

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Edward Instructor
Florida
Edward
 

That engine variant only came in two vehicles, 166.057 and 166.058 if the donor engine comes out of one of those cars and it has the same designation of 276.955 you should be ok.

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Martha Technician
California
Martha
 

Not sure I'd be putting a whole engine in if I had a bad camshaft… There are problems with the camshaft pulse wheel slipping. This will require camshaft replacement. Cam phasers do fail, Don't install cheap aftermarket. Yes there is a tsb, see attached, regarding rattle noise on startup,..this will not cause cam misalignment or the codes you have. Timing chain can be replaced by rolling in…

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Alexander Owner/Technician
Pennsylvania
Alexander
 

Have both bank 2 camshafts removed and cannot locate scribe marks on reluctor or cam. Needs intake came regardless due to pitting on lobe. I asked local Mercedes Benz dealer about service timing chain with master link. Parts consultant could not locate. Have no problem purchasing chain crimper/ breaker kit for job. Just looking for experience if it’s a worthwhile repair vs replacing…

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Martha Technician
California
Martha
 

Yeah, that cam looks pretty bad…motor R & R is an awful lot more work than a cam shaft and chain… Some of the early camshafts didn't have a scribe mark, and MBZ had a special tool to install to make a mark…although many dealers don't even have it… Note: try checking a 40 degrees and see if you see anything, See attached instructions. The parts guy at dealer needed to open the box that the…

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Alexander Owner/Technician
Pennsylvania
Alexander Resolution
 

Customer decided to go with a used engine. Installed used engine and vehicle is running great. Thanks everyone for the help. The cost to repair this engine with the damaged lobes and worn timing chains out weighed the cost of a used engine.

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