Did something stupid now need suggestion of best route to fix
 

The headgasket on my M103 deteriorated due to lack of coolant changes by the previous owners, and needed to be replaced. When I pulled the head I marked the position of the cam sprocket and the timing chain. All was good.

I got the head back from the machine shop. I had the shop do a valve job, new guides, seals, etc. on the head. It looks great. They removed and installed the cam, and rocker assembly so it was ready to bolt onto the block.

Now comes the problem. I neglected to verify the position of the cam, so now the head is on the block, and I'm close to 180 degrees out on the cam timing. I can't rotate the cam without hitting the pistons, so I figure my options are to either: 1) pull the head back off, or 2) pull the rocker assembly and repostion the cam.

I'm assuming that if I pull the head I will have ruined the headgasket seal. Is this correct? It would be my preference to pull the head as I think that would be easier than pulling the rocker assembly, but any suggestions would be appreciated.

Thanks.

Pull the rocker assy. Then get the crank lined up, then the cam. You are correct that pulling the head will probably need a new head gasket. Not always, but most of the time.

HTH,

If you turn the crank so that it is 10 degrees before top dead center, you can then rotate the cam to the alignment mark, then rotate the crank to top dead center, set the timing chain and you are done. Remember, it is only interferance when the piston is at top dead center.

Jim's solution is dead-on as far as simplest approach.

BTW, if you do the "pull the head" route not only will you have to replace the gasket but the head bolts as well. If the current ones have been torqued, they have also "stretched". These are one-time use bolts.

The repair manual indicates that as long as they are in spec (basically a certain length when out of the head) They are fine and can be used again. I did not replace mine as i followed the MB manual and they were within spec.

Did I do wrong?

The bolt length being within spec refers to the "stretch" limits. Basically, if the bolts haven't reached their "stretch" limits, they are within spec and can be reused.

Typically, if they have been torqued, they will stretch, which is why they are generally a one-time use item...which is also why you can't solve a leaky head just by tightening down the bolts...that won't seal the head, just stretch the bolts even more.

My personal experience is that head bolts are a one-time use item (and not just MB), so I always use new bolts when performing head work...a cheap investment considering what else is at stake.

Thanks for the explanation. I had insured that they were within spec, but will replace them no matter what if I have to do this again.

Thanks again and have a good day

Follow-up results
 

Thanks Jim for the easiest solution to the problem. I rotated the crank a bit, and that allowed me to move the cam to the proper position. After installing the tensioner I rotated the crank manually through the whole cycle a couple of times to ensure everything was set properly, and all was good.

I fired up the car for the first time last night. All seems very good. I had a lifter that was slow on getting pumped up, but it quieted down after 2-3 minutes. I'm giving the cooling system several flushes to make sure all the oily deposits are out then I'll change the hoses, and fill it up with MB coolant.

Thanks again for everyone's replies. I hope not to have to do that job again for a long time.

--Dean