Uranium238

I recently did oil on an in-law's CLK55 by draining out of the bottom using the rear drain plug. The sucker's pan threads shredded and broke when removing the drain plug bolt!

We managed to seal it up, but was given an oversize plug to tap the pan with. While this may be routine on other cars that have this issue, the pan material appears to be insufficient to accomodate the oversize plug. We used an anaerobic sealant that was oil resistant to stop the leak from the broken threads.

Now my question is, should I dare attempt to use the driver side front pan drain for the next change, or buy an oil extractor and go through the top? Never seen broken threads on an oil pan in my life, unless whoever did the oil before crossthreaded the plug!

Amir_AMG

ive heard of it happening on older benzos multiple times. honestly, I would use the top extractor method, its a pretty good investment and makes it a lot easier

mrwhattie

What I would advise you to do is buy a helicoil thread kit and insert a helicoil, these are very effective in repairing threads in aluminium and then you won't have a problem with future sump plug removals when doing oil servicing. If you go the route of sucking the oil out of the dipstick pipe, a large amount of oil will remain in either the front or rear part of the oil pan,(not sure which side the dip stick goes into) this is the reason for 2 drain plugs being fitted. Easier is not always better!

tw2

I would buy a new pan and seal. I wouldn't be comfortable with any other fix in the thin metal around the drain hole unless you weld it closed. Then I would drain it from the top in future. You get 95% of the oil which ever way you want to do it. You are never going to get every atom out. From memory the pan drains sit above the bottom of the pan anyway so you won't get all of it. I read a MB tech saying you actually get more oil by extracting than draining, don't know how true that is.

mrwhattie

Looking at the photo of an oil pan you will notice the dipstick pipe is in fact at the rear of the engine in the larger compartment. The front compartment accommodates the oil pump, and probably holds a liter or so of oil. The drain plugs are both right at the bottom of the oil pan, and l am sure 99% of the old oil will be drained if both plugs are removed.

floridawriter

I agree with mrwhattie. You need to drain from both the front and rear drain plugs. The front reservoir holds at least a quart of oil. Using a vacuum extractor will never pull all the old oil out of the M113 pan.

insame1

MB uses extractors as have I for years. There is nothing wrong with doing topside oil changes.

Khan 55

Like TW2 said. The pan isn't expensive. Rather buy another or like someone else mentioned fit in a helicoil. Did my oil service on tranny and sump and two bolts on me tranny sump were loose like you cant imagine. The threads were pulled sadly. Luckily me I got away with thin wall inserts on them. Hadta drill a lil deeper and fit them in with red seal Loctite. Was able to torque them up afterwards and now everything is happy.


If it was possible you should have drilled the threads out on the sump drain nut, tap in new threads with a slightly bigger sized plug. Sure you could have found something that works.