If you have the right crush washer, either the plug is not tight enough or there is some dirt, etc. under the washer. If the latter is the case, you don't have to wait until the next oil change. Loosen the plug (don't remove) and clean underneath the washer with a cloth or toothbrush. If it's not the right washer, you can remove the plug and put your thumb over the drain hole and not spill more than a few drops of oil. Push in on the plug as you loosen it. When you have it unscrewed, slide your thumb over the hole as you remove the plug. Just have someone to help you and do the job when the engine is cold. Have a drain pan in place just in case. If you tighten the plug with a combination wrench, it is unlikely that you will over torque it.

With new parts, it's also possible that some casting flash or a small piece of metal where the drain hole threads were cut got left behind.

As for RTV, I've never seen it help with drain plugs. The reason metal (copper or aluminum) and plastic washer gaskets are used, is because they crush to seal and they also take the tightening of the drain bolt much better.

Copper or aluminum washers make wonderful seals in such locations.

You probably only need to loosen the bolt and re-tighten it to cure the leak. I've had this happen a time or two over the years.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

"As for RTV, I've never seen it help with drain plugs."

I am sure you don't use RTV on drain plugs.... so you would not see it help.... or you are not following my instructions to let it make a gasket by setting up overnight before installing.....

The plug has been tightened 'some more' as of last night, and overnight, my greasy metal friend didn't even mark his spot. Not a drop! So, looks like I was just being oversqueamish with the tightening

Stripping out a bolt with all of that arm strength will do that to you.

The other extreme is having a drain plug fall out.
That happened to me several years ago with a Dodge van. I happened to see the guage pressure suddenly drop, turned off the engine, and coasted into a service station. Talk about luck!!
New drain plug and all was well.

Note: I paid a local indy to do the oil change as I was pressed for time. When I related the story, he fired the mechanic.

__________________
Charles
1983 300D, bought new, 215k+ miles, donated to Purple Hearts veterans charity but I have parts for sale: http://www.peachparts.com/shopforum/mercedes-benz-cars-sale/296386-fs-1-owner-83-mb-300d-turbo-rebuild-parts.html

Webwench,
Now you know exactly how much effort you need to seal a copper washer.
It is not easy to strip out a sump plug with manual dexterity unless some leverage is applied (or extreme brute force ).
I use a controlled effort to tighten most bolts/nuts. Combined with the fact that smaller diameter bolts have smaller heads and the spanners are shorter, (tends to reduce the effort applied too) this generally limits the torque applied to the torque which can be tolerated, or less.
With MEATY bolts and nuts, I apply "maximum effort". This combined with the longer spanners for the large sizes, allows just the right amount of torque to be applied.
For critical applications, I break out the torque wrench.

__________________
Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.

Leathermang, I've seen it used on several cars I've serviced, and a simple change to a new cooper washer stopped the leak after cleaning all the RTV off and making sure the surfaces were true.

The problem with RTV, even if you let it set up, is that as you are tightening the drain bolt, it gets scrapped off or bunches up under one part of the plug.

I have seen people slow a already present leak by smearing RTV around the leaking drain plug, but I don't recommend this either.

You guys ought to go to work for DoD. You over analyzed this minor problem ad-nauseum. The answer was always: Re-tighten the dadburn plug!!! LOL.

__________________
N. Hodges
1994 S350
1987 300 SDL (for sale)

nhodges, if you read the thread she referenced in the first post ....

"The conclusion seems obvious: I've singlehandedly managed to strip the threads on the drain plug, rendering my new Mercedes undrivable the first time I tried to do any maintenance on it."


You can see why we were looking at other answers.... this ' girly-girl' has arms the size of Hulk Hogan...