Oil Galley Plugs, Conventional Wisdom Options

[adolimpio]

I've read a few threads about the plugs, but there were some competing opinions, so I would like to ask for the latest thoughts.

1. What sealant should be used? One thing was clear - NO TEFLON. The most compelling suggestion was JB Weld. Is that a reasonable solution?

2. What kind of plug? Many opinions say NO to brass or aluminum because their head could be easily stripped. Steel was suggested. How about stainless? Any issue with the different expansion rates between the case and the plugs?

One thing is clear - they should be replaced. Of the 11 plugs, 2 almost fell out. They were definitely potential sources of future leaks!

Thanks for your thoughts!

[Superhawk996]

I'll stir the pot. (IMG:style_emoticons/default/stirthepot.gif)

Aluminum plugs are my preference. In my engineering judgment there is no point mixing dissimilar materials when it comes to galley plugs. Not saying steel can't be used, Per Mark's guidance and tribal wisdwom, others most certainly have been used steel with success.

My reasons for my perference of aluminum plugs:

1) The factory plugs are aluminum. Why? To avoid the potential for leakage that can occur with dissimilar expansion rates. Granted, the OEM plugs are press fit and has a different type of failure mode than the threaded interference fit of a NPT plug. NPT is less likely to leak than a press fit but NPT's and associted tapping operations x 11 holes would have been more expensive to use in production.

2) Potential for galvanic corrosion increases with dissimilar materials. Negligible concern for sure but why add potential for galvanic corrosion in a pressured, potential oil leak path.

3) I've heard the complaint that Aluminum NPT hex's strip. I've never had this problem of stripping an aluminum hex on installation. As with the factory galley plugs, my view is that installation of the Aluminum NPT should be permanent. If the orginal set has been undisturbed for 45 years, I'm not going to plan on ever removing aluminum NPT's after a rebuild. Sure an engine could blow and there would be the need to reclean the galley but I'm not going to plan for that kind of catastrophic failure - the factory didn't nor will I. If need be, the aluminum NPT's can be machined out and replaced later, assuming the case was even still salvageable.

4) My preferred install method ensures a light shrink fit (same as the OEM plugs) in conjuction with the NPT. Put the oil galley plug in the freezer (that's why some call them freeze plugs (IMG:style_emoticons/default/av-943.gif) Just kidding . . watercooled thing I know ) for about 1/2 hour before you need them. Lightly heat the case with a torch. Doesn't need to be raging hot (200F is plenty) so let's not start debating about warping cases. Now thread in the the NPT plug quickly with just a light dab of blue Locktite mostly for lubrication purposes to ensure no thread galling occurs on install. As the case cools you'll end up with a light shrink fit.

Now as the case expands and contracts you have identical expansion rates, a light shrink fit, the benfit of multiple threads as a labrynth seal, a bit of locktite as thread sealant. It won't leak. And as an added bonus, that plug isn't coming out on its own - ever But, as noted above, don't expect to remove it easily in the future. Aint' gonna happen. It will have to be machined out.

Again not saying steel can't work, just that aluminum is my personal preference.