2012 C250 P0340 triage
 

Hi all, I have a 2012 C250 with approximately 80k miles.
I recently started experiencing long cranks (extra second or two), a check engine light, and a P0340 code pulled by an inexpensive ODB II reader.
Google searching led me here where I read all the threads I could find. I am trying to DIY the repair, but not sure where to go next.

So far I have replaced the camshaft position sensors.
I pulled the valve cover off and observed the following:

• the timing chain does not appear to be stretched
• cam adjuster sprockets don't look worn
• with the crankshaft pulley at 0 degrees, the marks on the larger, outside part of the cam adjusters line up with the marks on the engine.
• the mark on the smaller diameter portion of the intake adjuster doesn't line up, but I assume that is okay

I don't know what or how to test continue triaging the issue. Is there a more scientific way of testing for timing chain stretch? How do I test for malfunctioning cam adjusters?

Below are pictures of my intake and exhaust cam adjusters when crank pulley is at TDC.
https://cimg1.ibsrv.net/gimg/www.mbw...fcbfbb1e74.jpg
Intake camshaft adjuster
https://cimg2.ibsrv.net/gimg/www.mbw...40ca25f253.jpg
Exhaust camshaft adjuster

Just checking again, I notice when rotating the engine manually, sometimes the intake camshaft adjuster marks are in line and look correct, and other times the timing mark closest to the cam is slightly ahead of where it should be. Should there be that much 'play' in the adjuster?

Also, sorry about the double post... there is another post in this forum describing the same issue. I would like to delete it, but can't figure out how.

Thanks for any advice!

Bump for help

Bump

https://mbworld.org/forums/c-class-coupe-c204/604301-help-long-crank-time-code-p0340.html

?

Update on status:
I put everything back together and drove it to an indy mechanic. The P034062 code had cleared after driving, but I fully expect it will be coming back.
The mechanic said that a pin in the intake camshaft adjuster had broken. The upper end estimate for the repair (without taxes) would be $5k. That would include:
1. Replace the intake camshaft adjuster.
2. Potentially replace the exhaust camshaft adjuster.
3. Potentially replace the timing chain and guide rails.
While the mechanic didn't mention it on the phone, I suspect also included in that is replacing the chain tensioner

My first question is: does $5k make sense?
Second question, is this really that difficult a job for a DIY guy? I looked at the threads, and they seem straightforward, but in tearing things down for my initial look, I started having issues even figuring out how to get all the piping out of the way. I couldn't find a good how to or video for things as simple as pulling the power steering reservoir off.

I plan on probably picking it up from the mechanic tomorrow and figuring out what to do from there.

Thanks!

Hi Chris, Were you able to fix the issue by yourself? I have the same exact issue that you mentioned, and I am taking it to an another mechanic shop to have a second eye opinion? My quote came to 6K, and below are the parts recommended by my first mechanic shop.

Remove and replace timing gear/phaser.

1. CAM sprockets
2. CAMshaft actuators
3. Roller chain
4. Chain tensioners
5. gaskets

Yes, I was able to repair myself.
I ended up replacing both camshaft adjusters (although only the exhaust was bad, the other was pre-emptive while I was in there).
I also changed the timing chain tensioner, although in hindsight I would just reset he existing one, there are youtube videos on how to do it.
I bought, but did not change, the timing chain, too much work, and too much potential for error.
Finally, I ended up having to replace the exhaust camshaft adjuster solenoid. I broken it tring to remove the camshaft solenoid. Word of advice, use an impact wrench, its too difficult to use a breaker bar.

If you are interested in doing it on your own, let me know, I have most of the tools you will need as well as a brand new IWIS timing chain I did not put on the car.

-Chris

Thanks for the update.

I would love to do it myself, but the details and the quote that I got from mechanic shop is not convincing. I have not done any major repair in the past, how easy is to DIY? For the same work you did?

Please clarify:
How much time you spent?
How much you paid for the parts?
How do you know what parts are bad based on the error code P0340? The reason I ask is, because the mechanic shop told me to buy the whole toolkit, plus additional items. I have attached the details.

https://cimg9.ibsrv.net/gimg/www.mbw...5d237ee599.png

It is difficult to know exactly what your mechanic is suggesting. I am not sure what the two cam sprockets are. Are you shur you have the M271 engine?

From this diagram, https://www.mercedesgenuineparts.com...engine--engine
I replaced these parts:
271-050-14-00-80 intake camshaft actuator
271-050-15-00-80 exhaust camshaft actuator
271-050-09-11 timing chain tensioner
271-050-05-78 camshaft adjuster valve (I broke the original by not first using an impact wrench to remove)
000-997-62-20 expansion plug (you will destroy the existing plug removing it)

All of those parts cost me approximately $1800. I also purchased a timing chain, which I elected not to replace, but did not return.
In addition to the above parts, I bought the following tools, which I can't find the receipt for, so don't know the cost:
* chain breaker for mercedes timing chains
* camshaft removal tool for m271, which holds the camshaft in place while removing
* impact wrench from Lowes

In all, the job was straightforward if you can follow the workshop manual for removing and getting access to the camshaft adjusters.
It probably took me 12 hours total, but I took pictures of every screw I removed so I'd know how to get things back together.
I did the job with the car up on ramps, so it was particularly difficult to get the alternator off and remove the timing chain tensioner.
There was some extreme breath-holding when I turned the key to start it up after getting everything back together.

As for determining what parts were bad based on error code, I don't think you can. I even doubted my mechanic's absorvation until I completely disassembled the intake camshaft adjuster and saw the work lip the pin fits in on the camshaft adjuster. See attached pic.

https://cimg3.ibsrv.net/gimg/www.mbw...cbf4db48a4.jpg

I believe the engine is same. Here is the details. https://www.mercedesgenuineparts.com...engine--engine
Also, what I noticed was when my car was kept in a flat surface(car garage), I did not see the issue. Mostly occurs when parked uphill.

I am not sure where to start and identify the real issue. Thanks for the update though.

Hi Chris

I need help. Do you have the soft copy of the workshop repair manual handy(C250)? Also, what tools do you have that I can buy it from you? Please let me know.

Let me know all the tools that became handy during your repair. I made a note of the impact wrench that you mentioned, and I am going to purchase one.

Thanks

Hello, I had the camshaft actuators changed after hearing noise when I start the car now I head the noise all the time after changing 3 times both of them thought they were bad! I had no idea what is that noise since it was never there on the original camshafts

A friend of mine who's a mechanic for MB of San Antonio said if your car is 10yrs old or less and has 120k miles or less and is having that problem Mercedes Benz will fix it for free!! That 1.8 is a known problem!!