97 C280, 104.94112089242 motor
 

Pulling the head to do gasket and valves at 256K.
Removed all 6 perimeter bolts and 2 coolant spigot bolts in center, but front cover doesn't want to come off. The MB WIS Cd doesn't show a connection to the intake cam through the adjuster on the cover. The passenger side seems like it's willing to come off, but the driver side (cam adjuster) is reluctant. Do I just need to be braver with the hammer and block?

Printed the DIY head gasket replacement article by Steve Brotherton. Per the article, I put crank on TDC #1 cylinder on compression (both cam lobes pointing to the sky) and tried to slide 4mm pins along the top machined surface of the head into the holes on the back of the cam gears. This can only be accomplished if the crank is at 5 deg ATDC. Engine has never been opened since new. Do I continue to remove head and just reassemble per article? If so why?

There is a pin that locates the timing chain rail. It is what is most likely holding the cover. I typicaly remove the pin before the cover. It is located behind the 5mm allen plug under the cam adjuster. It is removed by pulling. You can pull it with a bolt, nut, and socket. Screw the nut all the way onto the bolt, place the bolt through the socket and screw it into the pin. As you hold the bolt unscrew the nut, which should start to pull the pin once the tension builds. With the pin removed the cover should come off relatively easy.

The cams lining up 5ATDC is normal for the mileage on the engine. It would be a good idea to replace the timing chain while you have it apart. That should bring the timing back closer to 0TDC although if you have the head milled it will retard the timing a degree or two but will not be of any consequence.

Thanks Dux,
After posting my question , I went back and looked, scratched my head, and re-read the DIY article by Brotherton and then....EUREKA!...his mentioning of the upper guide rail pin registered. The MB WIS confirmed removal of this by the diagram although no instructions. Used your home-grown certified MB shop tool to remove it and voila! the cover came right off.:D

A stretched chain explains the 5 deg cam timing retard to my satisfaction and I will put in a new chain and tensioner.

Again, thanks for your help,
JOhn

Afterthought.

I can't think of any problems with this, but somebody else might be horrified.

When I install a new timing chain, I plan to connect the new chain with the old and crank it through by hand until the new one comes up the other side.
I will have moved the crank through x # of rotations to do this and I assume that it won't care, as long as the cams are timed correctly by the dowels and the crank's on TDC with the intake cam sprocket fully retarded by turning it, independent of the cam and crank, clockwise to the stop.

The chain tool seems hard to come by as a loaner, so does anyone know where I can get a master link, ala bicycle or motorcycle, for the MB duplex chain?

With the head off you can wind in the chain no problemo. Don't let the slack end get caught around the crank gear or you could damage the timing cover. Not likely if you proceed with a bit of caution and common sense.:rolleyes:

I wouldn't recommend a clip style master link. You can peen the master link without the M/B tool, although it does make it easier. With a large and small hammer it's doable. :eek: Assemble the link, hold the large hammer behind the link and use the smaller hammer to peen over the end of the link. The larger hammer will soak up most of the blow and you don't have to get too aggressive with the small hammer to get a decent peen.:cool: