Monday, January 20, 2014

Dow Corning 4

When I was packing up tools and supplies at home, one of the things I thought might be useful was a tube of DC-4.  I originally bought it when was doing maintenance on my airplane as it was an FAA and manufacturer approved grease used for a variety of things...including, of all things, lubricating oil filter gaskets.  It is sold in a rather large tube...and usually one is a lifetime supply for most people so after 7 years of airplane ownership the tube I had was still 99% full. Its primary purpose is actually a dielectric grease (not electrically conductive and helps impede corrosion in electrical connections)...which I thought might come in handy on a boat.

So, today as I started chasing down a couple intermittent power issues, I go a chance to use a little more of it.  I have never seen the exterior cockpit lights (the arch and step lights) work.  I checked the light sockets and no power was there.  I checked at the switch in the cockpit and no power there either.  I went into the engine room since I know there is a large power distribution panel there.  Of course, the manual I had that numbered the circuits for the arch and cockpit didn't match the panel so it became a bit of a guessing game. I removed, checked the fuses, and reinserted the fuse holders and went back to check the lights.  Suddenly they worked.  So, it appears connection corrosion was the issue.  I've also had intermittent power in the port forward berth and port head, so I figured it was time for some general maintenance of the panel.

I removed each fuse holder, removed the fuse from it, checked the fuse, lightly coated the fuse ends in DC-4, and reinserted the fuse.  I then used a Scotch Bright pad to clean up  the terminals on the fuse holder, gave them a coat of DC-4, and reinserted them in the panel.  After doing this to the 20 or so fuse holders, I climbed out of the engine room and went and checked all the DC circuits on the boat.  Everything worked spare a couple bulbs that might be burned out.  I'll go and check them...and likely install them using DC-4 as well.

Hopefully the protection added by using DC-4 will put an end to these intermittent power least for a good long while.


  1. I used to sell a ton of this stuff when I was in aircraft parts. It's good stuff.

    Get yourself some Dow Corning 795 in the caulking tubes. It works much better than silicone for stuff like rebedding ports and it cleans up soooo much better.

    S/V Kintala

    1. Hadn't heard of 795. I actually purchased some butyl tape for rebedding hardware above the waterline...tried it today. It is a bit slow to use, having to take your time while tightening things, but is easy, not messy, and seems to do a good job. Guess I will find out soon enough.

      Does the 795 work for below the waterline?