Does the W123 differential fill plug have a crush washer?
 

I was always taught that plugs with parallel threads used a crush washer (like the oil pan drain plug) and that plugs with tapered threads used sealant (teflon tape, pipe dope, etc.). Today, when I drained my '85's differential (yes, I removed the fill plug first), I discovered that the fill plug, which has parallel threads, had no crush washer. :eek: It didn't leak, either. Phil doesn't list one in his inventory. Is there such a thing? What do you have in yours?

nope.. none.. well not on mine either...

I suspect that diff. oil is heavy enough not to seep past all the threads. No, neither plug uses a washer.

No washer. Use some thread tape if you want.

i suspect you will find that it is a pipe thread.

tom w

Instead of pipe dope, I used anti-seize!! My days of wrenching on those plugs are OVER!!

Pipe thread
 

Yes, both plugs are pipe thread. The drain plug is a taper pipe thread while the fill plug is a parallel pipe thread. See http://mdmetric.com/tech/tic1a.htm

Anti-seize
 

That's an interesting idea (as long as it doesn't leak :D ). It would be especially good for the fill plug, as the plug is steel and the diff cover is aluminum. I may try it, thanks for the suggestion.

I asked this question some months ago.......
 

my '85 300D does not have a seal ring under the lip on the differential fill plug either......was a bear to remove, way tight......but the fluid is kinda viscous and does not (is not supposed to) be higher than the threads......

Teflon Tape......I am not a big fan of Teflon Tape either.....be careful if you use it......if Teflon Tape is improperly applied, little bits of the tape can wind up inside of whatever it is that you are sealing.....not too big a deal on a differential....but in a hydraulic system the little pieces get into the valves and such......never allow the teflon tape to be wrapped beyond or to the inserted end of the threads......

SB