View single post by Esprit2
 Posted: 09-30-2017 03:52 am
PM Quote Reply Full Topic


Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 341
I don't 'know' this is what your drain plug is, but...

There are aftermarket drain plugs that look much like an old-school Thermos bottle stopper. A rubber plug with a lever on top. Insert it into the bottle and fold the lever over. In doing so, the lever's cam-base pulls up on a central rod through the rubber stopper, compressing it. As the plug compresses, it expands, sealing itself into the throat.

The aftermarket drain plugs replace the lever with a central shaft that's threaded on the outer end. Tighten a captive nut to pull on the shaft, compressing the plug, expanding it into the drain hole. It's a J. C. Whitney sort of thing, but widely available.

They were the quick, easy option to fixing it right after you'd buggered up the drain plug. The internal threads in your photo look intact, so I'm guessing the plug itself was screwed-up. It was common for the hex to get rounded off. Rather than fix it correctly, someone put in an expanding rubber plug. You would do well to fix it right with a proper, original plug.

I can't confirm the size of the J-H OEM plug, or that it was Whitworth. I defer to those who say it was. But the original Lotus 907 drain plug was inch. It was later replaced with a metric plug with a flanged 18mm hex head. Both plugs used a sealing washer. A fiber washer was most common, but soft aluminum or brass sealing washers were also available.

A036R6014ZL - Drain Plug, Sump, INCH (originally used on the 1965/ pre-metric Lotus Elan Fixed Head Coupe)
A036R6014Z - Drain Plug, Later.
A075W4057ZL - Washer, Drain Plug (originally used on the 1974 Lotus Elite S1)
A075W4055Z - Washer, Drain Plug, Later (ie, 910). Still fits all.

For your J-H, it would probably be best to stick with a J-H source, like Delta Motorsports, or Martin Robey. Get the one known to fit... and a sealing washer or two.

They're known to corrode/ stick in the sump, so I apply Anti-Seize, or Teflon tape to the threads. Tighten firmly, but don't over-tighten. You're dealing with an aluminum sump and brass plug, so neither thread is particularly strong.

"IF" your car is a MK 1 with the oil separator can on the firewall, then the oil drain hose that goes back to the sump used a banjo bolt fitting. It should be re-installed with fresh sealing washers on either side each time. From what you describe, it doesn't sound to me like there's any provision on your car for an oil return line.

Tim Engel

Last edited on 09-30-2017 04:12 am by Esprit2