So this past weekend, my great niece (all of 9) helped me to do a diesel purge on my 81/84 "hybrid" 300D. Used SeaFoam (it worked, IMO...the glass bottle I used was almost BLACK with fluid when completed) and once completed, decided to replace the filters. Jeebus Peebus...apparently that was the hard part!

Naturally, I have the "O1" secondary filter housing (swell), so I decided to use the aluminum crush washer again, and replaced the lone O-ring with one from a metric HF set that appeared a match. Upon tightening everything up...ooozy McFloozy out of the top of the bolt, and cranking it down didn't help, either (btw, a 7/8" socket or wrench will work on that bolt---mine must be 22mm in size). Meh. Tired and losing daylight, I decided to fiddle with it later.

Today, I tried using a combo of the following, a 3/4" fiber washer with a 3/4" machine bushing (see items below). Umm, no.

http://www.menards.com/main/tools-hardware/fasteners-fastener-accessories/washers-spacers/flat-washers/3-4-x-1-fibre-washers-1-pcs-box/p-1444440193352-c-8945.htm?tid=1095281669387988619

http://www.menards.com/main/tools-hardware/fasteners-fastener-accessories/specialty-fasteners/bushings/3-4-x-1-1-4-x-14-gauge-machine-bushing-1-pcs/p-1444440112760-c-9547.htm?tid=7655826416167690244

Basically, I put the metal washer on next to the bolt, with the fiber washer underneath that. I noticed they both "wallered around" the bolt, so I wasn't sure they'd seal. Yeah, when I tightened and started...leaked like a sieve. Next attempt? Straight fiber washer. Tightened the beejeebus out of that, sprayed Brakleen, let dry and started. It seemed as though it was not going to leak, but occasionally, I came up with fuel on my fingers when touching the area around the washer. And it seemed to be weeping, so...attempt 3; bolt/fiber washer/old aluminum crush washer/housing (in that order). Thought perhaps the combo would keep it from leaking and...success? Perhaps; didn't seem to leak, but I decided to drive it and see. 15 minutes later and...weepy, weepity, weep...similar to when you found out what happened to Ol' Yeller. Again, tired and losing daylight...decided to give up and try again later.

What I'm looking for is a solution I can suggest that nearly ANYONE who frequents this forum can find easily in their area. With parts becoming more and more difficult to find, this is going to be an ongoing concern with these filters. What I will try next is the following:

1. The Right Stuff, from Permatex (see link below). Look, let's face it, all we really need is a good seal between the housing and the top of that wascally bolt. This stuff is designed to form on surfaces and conform to any imperfections on said surface (which I think may be our problem in the first place...because the housing has gotten gouged over time which creates a leaking area), and can be tightened and used immediately. Only issue (besides it's expensive)? Says it's not supposed to be used where it will come in contact with gasoline. Well, diesel ain't gasoline, so...I think it's worth a shot. I'd use it by putting a bead on the housing, then immediately putting the bolt/filter on and tightening.

Permatex 3 oz. the Right Stuff 1 minute gasket 25229- Read2Reviews onPermatex #25229

2. Peel & Seal. I used this on the roof of my house to seal a leak around a bathroom vent pipe. It's basically a thin aluminum with a rubber backing and adhesive; in this case, I'd cut a piece to fit the housing, cut out a hole in the center, then install the bolt/filter and tighten.

Shop Peel & Seal Instant Waterproof Repairs 6-in x 25-ft Aluminum Roll Flashing at Lowes.com


3. O-ring on top of the bolt itself that fits tightly (bolt/o-ring/housing). If I can find one that's a match, this might be the easiest fix of all. After all, an o-ring smashed down should likely seal the leak, as I think it would be self-conforming to any imperfections in the bolting surface on the housing.

Stay tuned. Will likely try these fixes tomorrow or the next day.