Help Needed With Mounting Oil Pan Skid Plate

[Squiggle Dog]

I purchased a beautiful oil pan skid plate (known officially as undershields) from sclass and was going to install it today, but it looks like I need to do a little work to get it to bolt up.


The rear of the plate mounts on the engine crossmember, and the holes are already there, so that looks straightforward. The front mounting arms are supposed to attach to the "frame", however, I do not have any mounting holes there. I did discover, however, that the frame has indentations where the holes should be drilled (smart thinking on the engineers' part).


The bolts that came for mounting the front arms are quite long, making me think there may supposed to be a spacer, or maybe each side of the box tubing of the "frame" is supposed to be drilled so the bolt can go through it? The factory image below leads me to think maybe a spacer was somehow utilized.


In my searching, I've noticed that the W123 chassis uses a similar design.


However, to use a speed nut (part number A 123 990 0891) like these ones do, I would have to cut a notch directly underneath the hole that I would have to drill.


Does anyone know exactly how the front portion of the W116 skid plates attach, and with what hardware? If I can't figure it out, I'll do it like the W123s, but I am a bit scared of cutting a notch into the frame--holes I can drill. I'll get it on there one way or another, but I am really interested in seeing exactly how the factory attached these on the W116.

[s class]

Squiggle, glad to see it arrived in one piece.  You are correct, the long bolts I sent you go right through the chassis leg, with a spacer tube as per the diagram to ensure that you don't crush the leg.  I will look tomorrow on the cars here to see if thhe spacer tube is removable, or welded in.  So don't drill/cut anything yet - let me check it out for you. 

[JasonP]

I still have not put mine back on yet after I fixed the oil pan leak.

Mine has bent arms, so it shortened a bit, which is why it was rubbing against the oil pan. I am going to use 1/4" spacers now to hold it just a little bit lower at the back portion of the plate. I tried using 1/2" spacers, but they put too much of an angle on the long bolts, and they would not go through the support beam.



I did not see any spacers used for the front arms when I took it off, although the washers were caved in, not so sure about the chassis legs.

I am curious to see how much space you end up with between your oil pan and the shield, Squiggle.

[Papalangi]

Hey Squiggle dog,
That indentation looks kinda like a spot weld to me.  See if you can bend a wire to fit in that big hole and pole around in there before you drill.

Michael

[Casey]

Interesting...curious about this myself.  I'd like to find one of these plates!  I just got one for a W123 but haven't gotten around to mounting it yet.

[s class]

If your engine mounts are shagged, the oil pan will rest on the skid plate. 

[Squiggle Dog]

Thanks for the responses. Spacers are cheap and easy enough to get if I need them. I'm curious to see how the factory mounted them. My engine mounts don't look very collapsed, but are rock hard, in definite need of replacement (along with the engine shock absorbers). I might hold off on the installation until after I replace the engine mounts and shocks.

[oversize]

Personally I think all 116s need these as the engine sumps aren't protected at all from the front....

[adamb]

Personally I think all 116s need these as the engine sumps aren't protected at all from the front....

Depends where you live, right? The closest I get to going off tarmac road is driving along manicured lawns at some show.

[oversize]

You don't have to go offroad to wreck your sump!  We have speed humps here and some gutters (kerbs) are a killer!  To make it worse, parking bays are shrinking and to get the back of the car in so it doesn't get hit by the passing traffic, you need to park deeper in the bay.  Thus increasing the risk of damage....

[JasonP]

Hey Squiggle, I just updated my oil pan leak post with my skid guard info. I took some pics and measurements for you.

http://forum.w116.org/mechanicals/oil-pan-leak!/msg106225/#msg106225

I cannot tell if my mounting holes were home-made or factory made. And if anyone has any idea what the oil pan ground clearance should be, that would be of great help to me. Mine is currently at 5 1/2 inches.

[Squiggle Dog]

Thanks for taking the pictures! I wonder if those holes are factory. In any case, I think I see how they work. I may be able to drill them lower to get a little extra clearance if necessary.

[Squiggle Dog]

I bolted the rear of the skid plate to the crossmember to get a better look at how these mount.



It appears that the "indentations" I saw probably were spot welds. However, I noticed there is a small hole on the rail that looks like it lines up with where the front mounting arms of the plate should go. I wonder if maybe it is a pilot hole that I can drill to size. It seems to line up, and I wonder if anyone can confirm if this is the proper location to drill. JasonP showed me pictures of where his is mounted, however, we think that someone may have drilled those holes at a later time.


The hardware that came with the skid plate appears to be the correct length to go through this rail. I think if I make the hole on the inner side of the rail bigger than the outer side, I can get a spacer tube the same thickness as the rail to slide in from the inside so that the frame rail does not get crushed when I tighten the bolt.


With the head of the bolt directly under the small hole on the outside of the rail, it indeed seems to line up with where the front legs should go. I can't imaging Mercedes putting a hole there and then expecting another hole to be drilled so close to it. It makes sense that they would mark where the holes should be to facilitate adding a skid plate if it was ordered at the dealer as an accessory.


So, my question is, those who have factory skid plates that know they are original to your car, can you look at the outside (toward the wheel) of the frame rail to see if this tiny hole is still there, or if it appears they drill out the small hole for mounting the skid plate? In JasonP's, pics, it appears that on one side they drilled the small hole bigger, and on the other side they drilled near the small hole. We both are not sure if his car came with the skid plate at the factory, or if someone added it.

[JasonP]

Squiggle,

I ordered my datacard from Mercedes-Benz, and there was no mention or code for an undershield. The code for an undershield is 481, and their email response described each code I had. To wit:

Engine: 617950-12-008801
Transmission: 722120-02-009034
623- Paint, Light Ivory
104- Interior trim, Bamboo MB-Tex
410- Electric sliding roof
440- Tempomat (cruise control)
461- Instruments, in English
466- Central locking system
491- U.S. Version
518- Becker radio
524- Paintcoat preservation
531- Automatic antenna
570- Front folding armrest
572- Front seat, right, with seat height adjustment; L.H.D
581- Automatic climate control
584- Electric window lifters (front and rear doors)
592- Heat-insulating glass
634- Elimination of first aid box
636- 15" tires
640- 15-hole light alloy rims
668- Mode of packing VE III

So, I got a hack-job. 

Good luck!

[Squiggle Dog]

So, I got a hack-job. 

Ah, dang. Well, the pics at least gave me an idea of how they mount. And... your car came with 15" tires? Wow, that must be really rare. I thought only the 6.9s had that as an option. Does your car still have the 15" bundts?