Has anyone torn into the timing components of a m276 (m278) engine yet? At 253,xxx miles I've changed the timing chain tensioners but just every now and then I get a heckuva rattle. It cranks and runs fine. I get the following codes:

The pos of exh cam bank 1 deviates from the specified valve. Implausible signal.

The pos of intake came bank 2 deviates from the specified value. Commanded position cannot be reached.

The first code is not there all the time but the second is. I just purchased a GL450 to have as a spare car (needed three rows to haul grandbabies). This will give me an opportunity to get the GLK in the shop and break it down to see what is up. It is now at 253k miles, uses no oil and has always had 7500 mile oil changes using Mobil 1 changed hot. Based on what I've read I'm thinking at least the intake on bank 2 cam adjuster needs to be replaced. Once you remove the covers you can see if the adjusters have issues while turning engine over by hand. I'll start there over the next few days.

I'm thinking with the type chain design they should be good for 300k miles. Any thoughts on that. There is a kit you can purchase off ebay that has all the timing components, new tensioners, chains, guides and all four cam adjusters. I have not decided if I'm going to go with something like that because I'm assuming it is made in China. The cam adjuster from MB is $1000/each
.

__________________
Jim

There is a kit you can purchase off ebay that has all the timing components, new tensioners, chains, guides and all four cam adjusters. I have not decided if I'm going to go with something like that because I'm assuming it is made in China. The cam adjuster from MB is $1000/each
.[/QUOTE]



never had 1 of those apart but as complicated as it is, i would never cheap out on the parts. dealer or the oe brand vendor only.

Is it possible the lower chain tensioner is the source of the noise. That would mean the whole cover comes off in order to inspect.

__________________
Paul

The cam adjusters on those engines are absolute garbage. If you've got 253k on them you're WAAAAAAAY ahead of the curve.

__________________

90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

There is a TSB (Xentry tip) that calls for installing a check valve to reduce rattle on startup. Do you have it?

Attached Thumbnails

 

__________________
Prost!

Yes check valves are installed.

Thanks for replies. I'll eventually break it down to see what is up.

__________________
Jim

Your timing chains are stretched at that mileage, they are only good on average to 170k miles, take the upper cam covers off and show a picture of chain tensioner piston , may be extended too much

Got the covers off. Everything is lining up fine. I did find one of the cam position sensors connectors loose and I may have had a leaking intake gasket. Not finding anything out of line in regards to timing. Bank 1 tensioner is sticking out further than bank 2.

Attached Thumbnails

   

__________________
Jim

Here are tensioners. Bank 1 extends out more than bank 2.

The fault code was on bank 2 cam timing not at desired. Also I was getting an out of range high indication on the intake manifold pressure.

Attached Thumbnails

   

__________________
Jim