My 9 inch diff has lube the color of coffee with cream so need to drain and refill. Problem is there is no drain plug so looks like I will have to drop the third member (chunk) to get the oil out. If that is the case it means removing wheels, pulling axles, dropping the driveshaft and unbolting and removing the third member to drain the lube. Am I missing some short cut here or did Ford really design this assembly to discourage servicing it. Would I be able to accomplish this by removing the pinion and drain it that way?

 

You probably could remove the pinion support to drain. I'd drill and weld in a drain in the bottom of the housing, since even with removing the center section you can't get all the fluid.

 

PITA but can you use a suction set up with a length of tube into the diff?

You will have to waste so new lube to "flush" it out, but less $ than the gaskets etc doing it the dropout way.

 

I've had no problems getting 100% of the old fluid out of a 9" housing...just takes patience and a lot of paper towels.

Now, as far as the notion that Ford would "discourage" servicing the differential...I'd take the convenience of the ability to remove the third member for gear swaps and other service on a workbench over the convenience of fluid changes. When you've pulled one 9" rear, you've pulled 'em all...and it just gets easier every time you do it.

Pat

 

I go with the mity vac vacuum pump and suction it out if it's not leaking there is no
reason to disturb the seal. Just like said above suction out as much as you can and
then put some fresh in and turn the tire then suction that out, do a couple times
and then refill. I use the mity vacc for everything suction out all the brake fluid from
the MC before bleeding brakes that way fresh fluid is in the lines versus a mix of old
and new. Power steering fluid not leaking why crack a line?, I also pull out a few oz
to a quart of tranny fluid every oil change to keep fresh fluid in my auto trannies.

 

Thanks guys for all the suggestions. I do have a Mity Vac style pump and think I will try that before opening up a non leaking diff. Thanks again!

 

easy removal of 3rd member....just takes a bit of time, its those pesky copper washers that get me.....i think they'd hold the 3rd member pretty well just by themselves.

 

Well, finally ended up pulling the pinion carrier and draining it thru the front. I used a vacuum pump to remove the oil from the rear of the housing that remained. I tried to drop the third member but just could not get it to turn loose. Yes, those copper washers are tough to get off without destroying them. Looks like I am going to need a pinion seal so now I can get it to the workbench and do it there instead of lying on my back. Oh, to have a lift to be able to stand up underneath and work. Thanks again guys for the help.