Is there a drain plug on the differential?

jseabolt · October 31, 2016

I've been doing quite a bit of maintenance on my '98 1500 Express here lately. Like installing a new transmission filter. It's got 145,000 miles on it.

One thing I would like to do is replace the gear lube in the differential. I have no idea what size differential is on my van. There are about 4 or 5 different sizes. All I know is my van has a 5.7 liter V8, 4 speed automatic on a 1/2 ton chassis.

I crawled up underneath it (yes I am that skinny) and found the filler plug on the passenger side but cannot locate the drain plug nowhere on the differential. Is there a drain plug?

txab · October 31, 2016

You pull the cover

jseabolt · October 31, 2016

OK, just like on a '96 Ford Explorer I used to own and my 68 Ford Fairlane.

I might just install a drain plug if I have to pull the cover like I did the transmission pan. It looks like the pinion seal is leaking a bit (not real bad) so I may just top it off and be done with it. Or does the differential oil really need to be changed that often? Considering there is no drain plug, then there is no magnet to catch any metal particles.

Sort of on the same subject (drivelines):

the other day it seemed as if the van was lurching at speeds below 5 mph. After about 10 miles, the condition finally went away but seemed to make a knock or thump when taking off from a red light at one point. I thought one of the spraugs maybe slipping.

I asked my father who I purchased the van from when was the last time the transmission filter had been replaced. He said he didn't know so I figured that was too long.

When I pulled the pan it was full of black sludge. I guess from where the clutch pack had worn. Luckily no chunks of metal in the filter or stuck to the magnet in the pan. So I guess that's a good sign.

So I put 400 miles it Saturday and the next day pulled the plug and drained 2.5 quarts out of the pan and replaced it with new fluid. In an attempt to get as much of the old fluid out as possible. I don't know if this is overkill or even necessary. I just figure the more old fluid and sludge I can get out of it, the better off I am.

I'll probably drain it once more when I do my next oil change.

Otherwise the transmission seems to be doing OK.

etex211 · November 1, 2016

Most rearends don't have drain plugs on them. The easiest way to add one is to drill a hole in the cover and weld a bung to it.

txab · November 1, 2016

Pulling the diff cover is pretty effortless and you can get out any built up gunk at the very bottom.

GsBowtie · November 23, 2016

Pulling the diff cover is pretty effortless and you can get out any built up gunk at the very bottom.

Yes, exactly. This is why i prefer to pull the cover.

mjoekingz28 · November 23, 2016

Why not just siphon out some and refill with fresh fluid until it drips out of the fill hole?

If the rear end isnt leaking I would leave it be and certainly not 'waste' effort drilling a hole into it. I kind of consider if it has a drain plug it is made to be changed. If it has only a fill plug it is made to only be topped off.

kstruckcountry · November 23, 2016

No. The reason there's no plug is that the cover should be removed, and the differential inspected.

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grampadirt · November 23, 2016

And while you have the cover off you can also clean the magnet.If there's any doubt about a magnet being there look at mine...that round looking thing laying on the bottom just below the ring gear.

barry G · November 26, 2016

My own burrowed a hole through it, original cover.

just the gear spinning for 20 years.

the replacements, it is easier to get one with a plug hole.

still not a drain hole, just another fill hole.

I worked a quik lube, a lot of siphoning.

check the vent tube as well.

we liked the diff plugs, as pinion angle could be off, and cause overfills on the side/front filler.

the diff plug is more at a center line of axles in the cover.

A weird thing can happen, even if seals don;t leak. Those axle ends need to have a temperature to dial in concentric, and take some smacking around for torques. A cold axle may lead to wobbling.

overfill keeps them too cold.

another thing I remembered, full drain to full new fluid.. you get some grumbles or pretentius wobbles until those layers take over the old viscosity. Takes some time.

the bigger the rear end, the longer it takes. I swapped over to synthetic, 20 yr old case.. took almost 6 months to really accept it. Driving fast helps.