DIFFERENTIAL SERVICE

REQUIRED TOOLS	MATERIALS (Check manual for types, amounts and applicability)	TIME
Socket Set Putty Knife or Other Scraping Tool Screwdriver	Gear Oil Friction Modifier Gasket Material	1 Hour plus gasket cure time

According the maintenance schedule of my 1997 Ram 1500 4x4 I either never have to change my differential fluids or I need to change them every 12,000 miles.  The 12,000 interval is required for severe duty use.  Since my truck sees mixed use (everything except towing) with the occasional door height water crossing, I decided to change out at 48,000 miles. That seemed like a nice compromise.  At whatever interval you decide to change your differential fluids, it is a pretty simple, albeit a nasty smelling, procedure.  Be prepared for some pretty nasty smelling stuff.  If you get it on your clothes, the smell may never go away so be careful.

Remember that my truck has a Chrysler 9.25 in the rear and a Dana44M up front so my pictures may not match what you have.  See you owners or service manual for proper fluid types and amounts.

First you need to drive you truck for a mile or so to get the fluid warm and thus easier to drain.  Go ahead and remove the bolt on the bottom half of the diff cover and loosen the top bolts 1/4 of the way out.  Be sure your drain pan is already under the pumpkin.  Wedge a screwdriver into the gasket and pry the bottom of the cover out to allow the fluid to drain.

Once the fluid has quit draining, finish removing the cover.  Wipe out the remaining fluid. I used brake cleaner to help me here.  Also be sure to wipe out any filings or sludge at the bottom of the pumpkin.  You should also do a visual inspection of the R&P teeth and other parts at this time.

On the Ram 1500s with the Chrysler 9.25" rear axles, there is a small magnet about 1" by 1" at the bottom of the housing near the flange. Be sure to wipe this area down to remove any accumulated filings.

After the housing is clean, you will need to remove the old gasket material from the axle and the cover.  Use a small knife, putty knife or what ever you can get your hands on.  Be sure to clean around the bolt holes.  This is also a good time to attempt to fix any dents or dings on your cover from four-wheeling. After thoroughly cleaning the cover, apply the new RTV sealant in a 1/4" bead around the entire cover flange and then go back and go around the bolt holes.

Let the RTV setup for a while (actual time specified on the RTV tube).  I waited 15 minutes then replaced the differential cover, tightening the bolts in a crisscross pattern to avoid binding anything and getting a good even seal.  At this point you can repeat the procedure for the front differential (if so equipped).  Try removing the fill plug on the front differential cover prior to removing the cover.  The factory painted the axle and the plug was frozen. I had to reinstall the cover and wrench on the plug to get it out.  After letting the covers setup for 2-3 hours after installation, I went back out and filled the differentials.  If you have a limited slip unit (LSD), pour in the friction modifier first, then top off with gear oil. This will ensure that there is enough friction modifier.

Once you think you have enough fluid, drive the truck around the block and recheck fluid levels.  There will be some seepage into the axle tubes, reducing the amount of fluid in the actual differential. Top off as needed and you are done.  Total time without setup time, 2 hours.  With setup time, 5 hours or more depending on RTV setup requirements.