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1998 SL500
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144 Posts
Discussion Starter #1
Hi!

So I screwed up and stripped the threadsfor the plugon my lower oil pan (SL500 MY98) and I'm now trying to figure out what options I have. I know that I could replace the oil pan but seeing that this would be a bit of a project, I'm looking for easier options first. I want to keep everything looking and functioning as stock so sealing the oil plug permanently and draining oil from thedipsticktube is not an option.

What I wonder now is if anyone have experience from mounting thread inserts in the oil pan, something like "Time Sert" inserts or similar? I'm kind of worried that there's not enough material to drill and fasten it properly in seeing that the oil pan itself is quite thin sheet metal? Do I have to worry about getting drill shavings into the oil pan when drilling out the hole or is this easy to get out afterwards?

Any other ideas?

Thanks!
Anton
 

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1992 Mercedes 300SL R129. 94 S320 Mercedes w140
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51 Posts
HeliCoil (sp?) or an oversized, self tapping plug are the only options I am aware of.
 

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1998 SL500 Pano
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154 Posts
I believe there is a Loctite product for creating new threads, as needed here. I just can't remember the name! A little help here!
 

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1992 Mercedes 300SL R129. 94 S320 Mercedes w140
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51 Posts
I believe there is a Loctite product for creating new threads, as needed here. I just can't remember the name! A little help here!
Yes. It is thread restorer. It is an epoxy type product. I’ve used it in the proper application with great success. However, the problem it would have here is the surface must be completely oil free or it will flake off. Getting the oil drain so clean that there would be no oil migration during the curing time would not be easy.
 

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2002 SL500 Silver Arrow
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626 Posts
I would recommend the slightly oversized self tapping plug and doing changes from the dipstick tube. I do mine that way and could do an oil change in a tuxedo -- since the oil filter is on top anyway - it is so much, cleaner, easier and safer (for me and the car). Hooked to my air compressor, my extractor gets all 8 qts out and I never have to worry about cross-threading or over- or under-tightening my drain plug. I do enough other underneath maintenance to give the underside a regular once-over.
 

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1998 SL500
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144 Posts
Discussion Starter #6
Thanks for your input, very helpful! I will for sure start changing the oil through the dipstick tube but for now I just want to correct my wrongdoings :)

Does anyone know what size the original oil drain plug is? I've seen both M14x1.5 and M12x1.5 and I have no way of checking on my car right now. It has the M119 engine!

Thanks!
Anton
 

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1996 SL500, 2000 E430
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3,713 Posts
Some years ago I used to help with fixing Mercedes club members cars with a retired Master mechanic.

he taught me a few things such as the wonderful applications of pry bars and the limited applications of torque wrenches. Many times we amateurs want to torque the most ridiculous things simply because the factory has a setting.

I remember somebody on a list asking the torque setting for the bolts holding the distributor rotor. Sheesh.

he said the only real reason for torque wrenches is transmission parts, internal engine parts and one or two other things.

I remember when I put the aluminum Oiler tubes on the M119 I made darn sure with a beam type torque ranch that I only gave it the prescribed 10 N meters. You were torquing the bearings back onto the camshaft so I can imagine making that too tight what it would do.

ever since years ago I stripped a thread putting a bolt in for a valve cover I’ve had a healthy respect for overtorquing things.

spark plugs? A good mechanic knows by feel how much to tighten the plug. Not me, I’m not that confident so I will use a beam torque wrench and not a click type to get it to those 20 N meters to 30 Newton meters setting

If a click type isn’t calibrated right you can royally screw up your spark plug hole. And I always use a flexible tube holder to hand start the spark plugs and avoid any chance of cross threading.

as far as the oil plug drain, for years I’ve used a Topsider for my Mercedes to just suck the oil out.

when I have drained it from the bottom I just use a Short handled 3/8” Dr. and just get it snug.
I’m thinking about this now but my master mechanic mentor was this old British Limey and he had three standards for hand tightening fasteners.

They were, tight, tight and a half, once more with feeling.

I can’t see who suggested it from this editing screen but whoever directed you to the other thread — I thought the Loctite idea sounded good.
 

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Outstanding Contributor
R129 500 SL 1991
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1,011 Posts
To repair the thread properly with Helicoil or epoxy thread restorer (yuck, I don’t recommend the latter), you would have to remove the oil pan anyway. Easiest and most permanent option would be to replace oil pan with new gasket. 30 mins work, since you’ve already drained the oil anyway.
 

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Outstanding Contributor
R129 500 SL 1991
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1,011 Posts
Scotty Kilmer does a good job there, but he wasn’t working upside down on an oil pan ?.

Here’s something a bit more entertaining: -

 

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1998 SL500
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144 Posts
Discussion Starter #13
Everything you need to know! Go to site below!



Although I really appreciate your input around this "google" thing (that seems great! :)), I'm having a hard time finding answers to my original question around material thickness around the oil plug in the oil pan. I'd like to know if there's enough material to get an insert to fit properly.

/Anton
 

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2001 SL500
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466 Posts
Although I really appreciate your input around this "google" thing (that seems great! :)), I'm having a hard time finding answers to my original question around material thickness around the oil plug in the oil pan. I'd like to know if there's enough material to get an insert to fit properly.

/Anton
Hi Anton,
If you have the plug out already measure the pan thickness at the hole.
Cut a short length of wire from a coat hanger and bend a 1/4 inch at one end over at a right angle.
Put a "zig-zag" at the other end to make a handle.
Wrap masking tap around the long part.
Insert the the "tool" up into the hole, and draw it back until the hook catches on the inside of the pan.
Put a mark on the masking tape level with the outside of the pan.
Voila! ... you have the thickness.
Even though the pan is quite thin, anywhere there is something bolted on, or through, there is a "boss" of thickened material to accommodate the threads. Also, the length of the plug should be a good indication of material thickness as the bolt should not protrude into the pan.
My only question would be: Is the pan aluminum or titanium? I ask this because titanium is quite brittle.
Maybe someone in the know on the forum could answer that question?

2621565


2621566
 

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Premium Member
97 E-420 (180K miles), 97 SL500, (93K miles) 2015 GMC Sierra Denali 2500HD CC/SB/4x4 Duramax(55K)
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4,228 Posts
as for pan material, I'd guess it is not aluminum or titanium, but plain old steel. A magnet would answer this question pretty quick.
 

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64 Posts
FWIW......

If you want to get to original as possible not replacing the oil pan.

Get a reducing bung / bung fitting that would receive the same size original oil plug{purchase and used a new oils plug and seal].

The attached photo is what a general /typical threaded reducing bung / bung fitting looks like. They are also available as a weld on unit. You would need to get the correct size.

reducing bung fitting.jpg

Then attach the reducing bung to the oil pan, your choice, welding on or drill and tap unit.

Regards

Joseph~
 

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1998 SL500
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144 Posts
Discussion Starter #18
To repair the thread properly with Helicoil or epoxy thread restorer (yuck, I don’t recommend the latter), you would have to remove the oil pan anyway. Easiest and most permanent option would be to replace oil pan with new gasket. 30 mins work, since you’ve already drained the oil anyway.
Thanks for your input! Are you sure though that this is a 30 min job? I've read that you'd have to loosen the engine mounts and lift the engine to access all of the oil pan screws?

/Anton
 

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1996 SL500, 2000 E430
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3,713 Posts
I didn’t realize it was so easy to remove the lower pan. I think this is what I would do if you want to do the job right. Yes put a new pan on.

you probably need a wire brush to brush off the gasket residue and I would see what kind of gasket sealant do you need.
 
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