New Oil Pan Drain Plug Thread Problem
 

Hey all,

Put a new lower oil pan (the stamped steel one - they weld a nut on the inside that the drain plug screws into) on my '94 E500 yesterday and after I got it all buttoned up I tried to put my old drain plug into the new pan and it would go in a little way and then I couldn't turn it any more (fingers only). So I assumed new pan they must have changed the threads at some point. Stopped by the dealer this AM and they are no different. My old plug fit into a brand new pan at the dealer.

So, do I pull the pan off and replace (which would require a new gasket I assume as I used the MB black stuff in a syringe to install plus new black stuff) or tap it out. Pan is easy to get in/out and I have no experiance tapping but I'm willing to learn. I always wanted a reason to get a tap set, maybe this is my chance. Third choice might be to grab a big wrench and see if I can get the plug in that way!! Worst thing - after I was done - I had to move the car around the driveway with no oil in it....just kidding!!

Randy
'94 E500

If you have only used your fingers and haven't tried a wrench on it, I wouldn't think it unreasonable to try to tighten it with a wrench using sensible torque (below bolt spec.). Get a new drain plug, also; it's great for peace of mind to have a spare in the trunk.(and cheap).

If you try to tighten it, you could easily destroy both parts. A tap is the proper tool, if you are convinced the threads are the same. the tap should turn very easily to clean the threads. Significant resistance and you should investigate further before continuing. Above all, do not try to tap incorrect thread pitch to match your plug.

Steve

I should add a good tool shop should have thread pitch gauges - can be a very handy item.

Steve

Clean the threads with a correct size tap, and put that NEW plug in. You only need to buy the correct size tap, without buying the whole kit.

Thanks for the input guys. I was down by our other MB dealer for lunch (where I bought the pan) and picked up a new pan, gasket and plug. I will try the new plug and if it doesn't work then I will put the new pan in and they will take back the old pan and gasket and credit me. Good thing is I can go home tonight and no matter what get it finished.

Thanks for the input.

Randy
'94 E500