Second tank post chain replacement yielded 34.0 mpg

I think I can call the increase in mileage confirmed.

Should have done it a lot sooner I guess...

Glad I found this thread, I started this process yesterday and realized I messed up, so now I'll have to press the master link back out and get a new one, despite using the FSM for a W124;the instructions listed nothing like what is listed here. Here's my dilemma:

I couldn't get the master link to go through the middle link or outer link, so I took calipers and measured the ID of the link holes, then measured the OD of the rivets, then took a drill and barely reamed the link plates out to match the OD of the master link rivets, allowing it to press through with no resistance. I used the link press face portion with the magnet to try and swell the heads, but the link rivet heads are barely swelled, with the outer plate loose but barely on. Now, after reading this thread and a couple of others as to how tight the middle and outer links should be, I'm sure I botched this due to the looser tolerances I created, even though I could now crimp the outer plate and finish the job. I don't want to risk destroying my engine.

Recycled for new members
 

Education.

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The combination of that pressure... AND the fact that a double roller chain puts very little side pressure on those pins will allow many of these to work ' just fine'..

HOWEVER....this also makes it possible to crimp those ends just fine without the very nice tool...

Two 2 lb hammers....one as an anvil behind the pin....
and the other tapping a sharpened drive punch on the center of that pin......

Very little expansion is needed given the situation to hold it in place.
There is no rush.... and not much hitting needed.... just be sure the anvil is in place...and TAP... a couple or three firm hits should do the job just fine.