Tag Archives: differentail

Work on the Truck

Part of living off grid and on a budget is keeping everything running. That most certainly includes the truck. At 172K miles the F-150 is still a great truck but to keep it that way requires a person to stay aware of what is happening with it and addressing issues before they leave you stranded. Last week I noticed that the rear differential was leaking oil. Everything was canceled and I got a ride from Shane into Missoula for parts.


Changing the fluid and checking all the moving parts is not that difficult. It should be done every few years once a truck gets as many miles as this one has. It only took a few hours and is nothing anyone should be intimidated by.  The drain plug is on the back side of the casing and takes a 1/2 inch wrench to open it up.


Once the drain plug is out you can get a good idea of much metallic particulates are in the fluid. The inside of the plug is a magnet that works to pull the any metallic fragments from the fluid while the truck is running. You will want to be sure to wipe clean.


The bolts on the casing should be loosened in a star pattern. When they all are loose and can be removed with no chance of putting any strain on the other bolts or the casing cover itself, put them aside to clean while the fluid drains. When all the bolts are pulled, very gently, use a tool to get in between the cover and the case to break the seal. Be very careful not to scratch or mar the surface with your tool or you risk a bad seal later on.  As soon as the seal is broken the fluid will start to drain out.


Give it twenty minutes or so to drain then pull the cover off. Cleaning the bolts and around the outside of the seal quickly fills the time.  (Be sure to have a drip pan of some sort under to catch it all.) Once the cover is off take your time to clean it well. A shop towel or shop quality paper towels work best.


Once it is wiped clean you will want to spend a little effort to clean off all the old sealant and any grime from the mating surface not only of the cover but the case itself. Using a plastic scraper takes a lot of the risk out of it. You can pick one up, with an extra blade, at Auto Zone for $4 or less depending on what part of the country or you’re in.


Inside the differential you’ll want to wipe out all the fluid from the bottom and down in the basin just inside the lip. Use a small portion of the new fluid to rinse it down. Only then put your new sealant on.


I used JB weld blue glue. There are different brands but whatever you use make sure if says for use on differentials. Once its on, line it up carefully and put it into place. Begin to replace the the bolts in the same cross cross pattern used to take it off. Tighten them gently and only enough to touch all around. You’ll need to let the sealant set-up for at least an hour before you tighten it down all the way. Be sure to replace the tags so future work, or future owners will know what fluid to use.   20180513_132918

I let it set up for a full 24 hours before I drove it. For the effort of a morning and for the $60 of fluid and sealant a great deal of stress, headache, and later work was dealt with. I had already lost over 2 quarts of the fluid (the trucks hold 2.5 quarts of differential fluid) by the time I had caught the leak. If I had not stopped work on other projects to deal with it, it would not have been long before entire differential would have had to be replaced.  Some of these unexpected little side line projects are well worth stopping other plans for. Being able to do such work for oneself is a skill that only gets better with time. Even when you find yourself under a truck and greasy to your elbows try to appreciate the fact that you’re in a cubical. Doing basic mechanics is just part of the off grid, homestead lifestyle; and try not to be intimidated by it.