Diff fluid change, how I made it easy

[USMCBuckWild]

I read all the threads about changing the diff fluids and decided it was time. I went with Valvoline Synthetic 75w-140 for the rear and 75w-90 for the front; apprx 2 liters in each.

The rear was pretty straight forward. Loosened the fill plug first, then the drain. Oil came out very dark and smelled as if it had water contamination. I made sure to jack up the front of the truck to get out as much old oil as possible (a little OCD, but oh well) used a gear oil transfer pump ($8.99 at walmart) to top it back off. Literally took all of the 2 liters.

Front came next. Read a bunch of horror stories about people having leak issues from the front covers, breaking bolts, etc. so I figured I would try something different. I happen to have a brass 1/8 NPT plug and an 1/8 NPT tap. So, I grabbed an 11/32 drill bit and prayed for the best. On the front of the cover to the right of the gear swell there is a flat surface that is about 45 degrees to the face of the cover. Its about 1/2" high and 2" wide. I made a little pin punch centering mark with a sharp punch and hammer to keep the drill from wandering, then popped out the fill plug. I strted drilling and popped right through and the oil drained out. It was RED and smelled very distinctly of ATF. I am almost 100% sure my front diff had ATF in it. I was pissed. Again I had jacked up the back of the truck to ensure as much fluid as possible came out. There didn't appear to be any debris, glitter or shine in the fluid (i drained it into a paint strainer). So I packed my tap with vaseline to catch the chips and threaded the hole very, very carefully. (To be honest I ran a series of tests and trials on scrap metal to get a feel for the tap and build confidence). With the hole threaded nicely I dabbed a touch of red loctite onto the plug and threaded it in, torqued it to approx 25 ft/lbs. then filled the front end with the 75w-90, it took about 1 and 3/4 liters of fluid.

A little brake clean to clean it all up and then a paint marker mark across each of the plugs.

Time involved from start to finish: 1 hour 15 minutes.
Beer consumed: 2 Bud Lights

 

[drdoom]

I like it, good job.

 

[BrianDye]

Nice. I need to do both of mine as well. I know damn well they have not been touched. Just gonna add it to my 19 page to-do list.

Ill probably do it when I install the lift and new parts. Might be a dumb question, but we don't have a drain plug on the front diff? Or do we, and its just a PITA to get to? I haven't read much on it, but no horror stories like you mentioned.

 

[USMCBuckWild]

Nice. I need to do both of mine as well. I know damn well they have not been touched. Just gonna add it to my 19 page to-do list.

Ill probably do it when I install the lift and new parts. Might be a dumb question, but we don't have a drain plug on the front diff? Or do we, and its just a PITA to get to? I haven't read much on it, but no horror stories like you mentioned.

No drain plug on the front diff. Th fill plug is 3/8 ratchet. Its a stamped steel diff, so if i screwed it uo I would have just welded up the hole.

Rear diff has both plugs and are 3/8 ratchet

 

[yoster]

Nice work. I'm about to do my front diff as well. I plan to just open the fill plug and use a fluid transfer pump to suck the fluid out. Same thing I plan to do when changing the trans fluid on the 'sealed' 6r60 lol

 

[USMCBuckWild]

Nice work. I'm about to do my front diff as well. I plan to just open the fill plug and use a fluid transfer pump to suck the fluid out. Same thing I plan to do when changing the trans fluid on the 'sealed' 6r60 lol

Funny you say that: I just installed a drain plug in the transmission sump. Utilized a 1/4 NPT tap and an air compressor drain plug, reinforced on the inside of the sump with a brass nut made with the same tap. Works pretty good, drains a little slower than I want but keeps it clean and simple.