Well, I've been habitually plagued with head gasket oil leaks over the 26 years of fun with my '91 300SE. Got the dreaded rear passenger side leak again after only 5 years and 45K miles since a new Reinz gasket.

So......... I decided to go ahead and re-torque the head bolts. What the heck, what's the worst that could happen (I tried not to think about it).

Finished it up today, I'll report back in a few days or so to report if it actually stopped/slowed the oil leak.

But, I observed some things when I did the job that I thought might be of interest.This was only a minor oil leak, no coolant involved that I could tell, and good compression, so maybe it was a good candidate.

Procedure:
I marked the head of each bolt at 12:00 o'clock with typing white-out, and removed/replaced one bolt at a time, starting at the left center and working out in each direction.
I cleaned and oiled the head surface under the bolt, checked the depth of the hole, cleaned and oiled the bolt, and reinstalled, torqued to 40 ft lbs, then turned it 90 degrees ( after doing all 14, I then went back and turned them all an additional 90 degrees in sequence).

Observations:
These bolts have been re-used 3 times over the years. They measure exactly 102 mm; absolutely no measurable stretch, no indication of necking. Mercedes says to re-use them, i think it's pretty safe.

All the bolts behaved exactly alike. Each bolt was hard to break loose, making that lovely snap sound; obviously none had come unscrewed or loosened excessively.

After breaking loose, they quickly became finger tight after less than 30 degrees of rotation. Obviously not a lot of clamping force left here.

When I re-installed the bolt it returned to exactly 12:00 o'clock with only 40 ftlbs or torque. So, again, not much clamp left

When I turned the bolt the first 90 degrees, I used a torque wrench just to see the approximate force - about 75-80 ftlbs for this first turn.

When i made the last 90 degree turn I set the wrench on 90 and it didn't click. Tried the next one at 85, and it clicked just as I reached the 90-degree turn. So, I ended up with about 85 ft lbs on torque after the last turn. All bolts went down smooth and linear, could feel they were in the stretch zone.

Big interesting thing: I ended up turning all the bolts an additional 180 degrees from where they were when I started. That's .875 mm, or about 35 thousands! That's a lot of gasket compression or bolt stretch, or something.
Probably a combo of gasket, a little bolt stretch, and a little recession of the head under the bolt.

Anyway, I'll see if it works, hope to dispel a few myths about this all-to-common issue.

Oh, here's a little info on the source of these head gasket leaks.
The 103 head receives ALL it's pressurized oil from a passage right next to the RR head bolt. Thus the source of the worst of the leaks. There is no oil passage in the front of the head, but there is a blind one drilled in the block next to the RF head bolt. It's a blind hole covered by the head surface, but oil pressure is there and works on the gasket eventually, just like the rear passage. The front timing cover is, of course, another chapter in the saga.

More later, wish me luck,
DG