Hi,
I am looking for confirmation of timing procedure for my 2012 ML 350 M276 Mercedes. Mileage: 160,000km. I bought the car because no technician in town was able to fix car for over 2 years. A good guinea pig that could turn out to be an excellent deal.

INITIAL CONDITION: Car was bought with severe rattling, loss of power and timing related codes.
Initial fixes: Complete Timing kit bought, ( Chain, guides, tensioners, adjusters and check valves replaced)- Rattling disappeared

RECURRING POST-FIX DTCs (after timing)
- P002464 (The position of the Exhaust Camshaft (Cylinder 2 deviates from specified value. There is an implausible signal)
- P001464: The position of the exhaust camshaft (cylinder bank 1) deviates from the specified value. There is a signal and implausible signal)
- P002164: The position of the intake camshaft (cylinder bank2) deviates from the specified value. There is an implausible signal.
+ Misfiring cylinder 4, 5, and 6

IMPORTANT: Tone wheels had lost position and moved. So Camshafts tone wheels had to be repositioned to achieve the tone wheel positions indicated on the Xentry document pictures..

MY TIMING PROCEDURE

1- Set timing at 40 degrees crankshaft (TDC);
2- Camshafts set at TDC and checked at overlap by turning engine 360 degrees. All marks aligned with positions on the tensioner bolts (per Xentry timing doc);
3- Installing tensioners: I rotated the engine to 40 degrees TDC; then fit tensioner for Bank 2; turned engine 360 degrees to overlap and installed tensioner for Bank 1;
4- Reluctor (tone wheels): I rotated the Crankshaft (17mm from 40degree mark) to the 53 degree mark to ensure (check) that tone wheels align 1/2 way in the camshaft sensor holes (as shown on the Xentry document);

Yet, car will not start and indicates correlation codes for B1 & B2 exhausts camshafts. The Xentry document is pretty confusing as information for the M157, M278 and M276 are all mixed up.

I would appreciate if someone could look through verify my procedure and advise if procedure is correct and provide me with a correction.
I would like to confirm my timing procedure before moving on with misfire checks.

Any help will be greatly appreciated.

 

What sensor investigations have you done?

Oil in cam position sensor or cam magnet connectors?

Oil in ECU connectors?

Oil in O2 or fuel injector connectors?

Oil in crank position sensor connector?

If this was mine I would replace cam position sensors and magnets, O2 sensors, coils and plugs. Then go from there.

Install new main and aux batteries. Electrical system needs to be near 100% perfect on these cars.

 

https://mbworld.org/forums/e-class-w...ml#post8435982

https://mbworld.org/forums/c-class-w...ml#post7697612

 

I had replaced camshaft sensors, camshaft solenoids.

I realize from the video that for the tensioner I started replacement from the left side first at TDC and then the right side on overlap.

the m276 doc I used was the attached WIS doc

 

Hi Chassis,
Camshaft sensors receive 12v power and generate 4.5v signal.

 

Good info. Are the harness connectors coated in oil? Open the connectors and post photos here.

 

Connectors are clean and no traces of contamination.
What I need is a confirmation of the timing process,; whether per my procedure I omitted something or did something wrongly in the timing process.

 

Re-reading the original posts, I would focus on being 1000% certain the tone wheel realignment is perfect.

Did you use the tone wheels alignment tool?

Do you have a picture showing the laser markings aligned with the tone wheels?

How did you fix the tone wheels to prevent future motion?

 

True! all tone wheels were off position. Some of the laser marks were wiped off and invisible to the naked eye. I used the tone wheel laser alignment tool to reidentify laser mark positions. Did a re-welder of the tone wheels to the camshafts.
What i suspect is a physical deformation of the tone wheels which may require some straightening. Segments seem to have previously been deformed and require some straightening so they can regain symmetry.

Key Questions:
- CRK Timing is done at 40 deg. ATDC "Ignition".
- Then to check proper alignment of cams, CRK pully needs to be turned 360 deg. to 40 deg. overlap, right? To make sure laser marks align with tensioner bolts (per WIS doc); see attachements A= timing at TDC ignition & B = Timing CHECK at 40 deg. ATDC overlap? Is tis correct?

- Is the tone wheels alignment verification through the cam sensor holes done at 53 deg. ATDC "IGNITION" or at 53 deg. ATDC "Overlap"?

Clarification on these two questions solve 90% my problems.

 

Hi juanmor40
In response to your question, I went for a cheap method. I simply made a 2 point welder of tone wheel to the camshaft. Cheaper than placing a costly order for brand new Cams. That's the little trick.

Tensioners: I fitted the tensioners starting with B2 at ATDC 40 deg. Then made a 360 deg rotation and fitted tensioner for B1. Here I think i missed the proper order. I guess it should be B1 first, then 360 deg. to fit B2.

 

I am reading, and re-reading the document. I do not see the 360 deg rotation explicitly said; however, I understand that, in a 4-stroke engine, for a camshaft to rotate 180 deg (from top mark to tensioner mark), it will require @ one full rev of the engine. 2 revs should put the mark at the top..
I understand it as:
1 - check at 40 deg after TDC --> Crankshaft pulley mark pointing upwards (see the photo there), Markings on the camshafts must be at the top, pointing away from the tensioners
2 - Then rotate engine in the same direction as the engine rotates when ON,
3 - UNTIL the 40 deg mark on the crankshaft pully aligns with the marking on the drive belt tensioner damper (2nd photo) --> Marking on the camshafts must be at the "bottom", pointing towards the tensioners

 

Thanks, That's what I was looking for on the timing side. Have you timed the W166 before following this procedure and it worked? We have the literature; experience will be an extra confidence booster for me because points on the WIS document really get me confused sometimes.

Next confirmation will be TENSIONER FITTING PROCEDURE. I do not have the entire MB software presently and can't find much. I am normally not inclined to youtube.
I bought the MB software from emanual online, used it on virtual box until a bug robbed it off.

 

Fortunately, I have not had that pleasure yet, though you can see in my signature 3 M276 engines in the "fleet". So I am getting ready for either of: VVT, chain tensioners, tone wheels, etc. I plan to keep these cars as long as possible.

Here this link has the documents you may need to complete your work: https://mbworld.org/forums/w212-amg/...ml#post8352168

Let me restart my garage laptop. WIS is in a VM as well.

 

Thanks so much. Anxiously waiting to hear how it all went with your repair while I throttle ahead.