after finally getting a 14mm allen wrench, i tried to just open the fill plug on my transmission to check the level and condition of the fluid. Alas the fill plug does not want to come out, even after putting the wrech into a jack handle for more leverage i can not break it loose, Anyone know any tricks to break it loose?

There's no easy way--just keep jerking on it. Someone clearly overtightened it.

You can try soaking it in rust penetrant--might help; might not.

Last resort--you can heat the plug with a torch.

But a big breaker bar or extension should work.

I should add--make sure you have the allen hole cleaned out well so the 14 mm wrench will go in all the way. Otherwise, you might strip the hole--that's a REAL mess.

Maxwell,

I insert the wrench, hold it with a firm load in the direction of loosening the plug, and then whack the end of the Allen wrench with a hammer. After a couple of good smacks it will budge, then I tap a little lighter until it goes about half a turn, and at that point it will come out the rest of the way by hand. I believe there is an aluminum seal ring, it may be copper, under the fill plug and it can stick to the two steel parts pretty good. Typically the corrosion products on these materials are less dense than the original base materials and the longer that plug sits there the tighter it gets.

I have never used a breaker bar on these and have never had a real challenge using the hammer. When I tighten them up I pull it tight by hand and then pop it with the hammer to snug it up good. I have been doing it that way since 1975 and have had no issues. Good luck, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

Try PB Blaster, you can find it at any parts store or Wal-Mar, just spray it on and leave it for a couple of minutes and then try it again. I've had great success with this product, hope it works well for you.

Thanks for the tips, I ended up using the hammer claw to pry the wrench, after hitting it a few times while pushing, but before i could hit it with a secon hammer it broke loose, got it drained and filled, turns out it was filled with gear oil, probably shift smoother with mobil1 ATF

no problem, my 240D has a problem right now also, I tried to start it and it sounds like the starter is not engaging. I just get a loud klunk sound when I pull the plunger out.

Any ideas?

Thanks