LF Rear Diff Fill Plug Tips & Tricks

[sheliable]

Servicing rear differential for peace of mind. Fill Plug is rusty, Ohio truck...

Soaking in penetrating fluid overnight. Looking for other tips from those who’ve been there before.

What tool do I use to get the plug off? Just a 3/8ths ratchet alone? Alan wrench socket ? A bit confused there.

Once I drain the diff it’s okay to spray the s*** out of the inside with brake parts cleaner to clean before refilling? Anything else I should do while in there? Grease? Replace plug?

 

[Curious Hound]

I wish you luck. Might have to re-apply and soak more than one night. Square drive that fits is the best tool. Might try tightening slightly before loosening. Sometimes that helps break the rust bond. Might need heat.

Do not drain the oil before getting the fill plug out. Otherwise, you have no good way to put oil back in.

 

[sheliable]

I wish you luck. Might have to re-apply and soak more than one night. Square drive that fits is the best tool. Might try tightening slightly before loosening. Sometimes that helps break the rust bond. Might need heat.

Do not drain the oil before getting the fill plug out. Otherwise, you have no good way to put oil back in.

Thanks mate, and yes I (luckily) thought of that after I removed about 5 cover bolts. That woulda been annoying.

 

[sheliable]

Why do they make the Fill Plugs this way and not like the oil drain plug for example? Quite a headache. Reminds me of the first time I torqued a drain plug on a Volkswagen after owning American my whole life... learned a lesson that day.

 

[MikeG]

Stick a 3/8" drive in the square hole and and crank away.... no, I don't know why they are that way, either. But it's hard to strip out a square hole.

 

[Curious Hound]

Why do they make the Fill Plugs this way and not like the oil drain plug for example? Quite a headache. Reminds me of the first time I torqued a drain plug on a Volkswagen after owning American my whole life... learned a lesson that day.

It's a common pipe plug (tapered threads, available from any plumbing or home improvement store) they've been made that way for 100 years or more. The guy who knows why died long ago but he may have passed the knowledge along to @RonD

 

[MikeG]

If the threads are a pipe taper, they WILL seal with enough torque. Whether or not that is a good idea on a differential fill plug, I don't know.

 

[97RangerXLT]

worst case scenario... find a good differential cover in a junkyard or get an aftermarket one...
remove old cover plug and all and toss it on the recycle pile.

AJ

 

[Curious Hound]

worst case scenario... find a good differential cover in a junkyard or get an aftermarket one...
remove old cover plug and all and toss it on the recycle pile.

AJ

This is the fill plug. Not on the OEM cover. Still many ways to get around it. Buy aftermarket cover with fill plug and just leave this old rusty plug the way it is. Or, drill cover and weld on a fill plug bung at the proper level. Or remove cover, put something in there to catch drill shavings and drill out the rusty plug.

 

[JMF661]

You poor poor, very rusty, people

 

[DILLARD000]

Soak with pentrating oil for 2~3hr..
A few gentle "love taps" with BallPeenHammer.
Drill+WireBrush clean exposed threads & general area.
Try removing with SquareExtension+Ratchet+CheaterBar. Repeat process 2~3 times.
Plan B = MapGasTorch.
Plan C = Drill out & replace plug.
Plan D = Give up on this plug, remove differential cover & install new Bung+FillPlug.
Plan E = New\JY Differential+Axle

 

[Grumpaw]

Pull the cover off and drain the oil, but get one of these first so your ready to go.
Pull cover and weld the bung into the cover and you have an instant fill plug.
Google up rear end weld in drain/fill plug with bung.

Even simpler and cheaper, get a 3/4 inch or 1 inch nut and short bolt. Drill hole in cover, weld nut to cover, instant fill plug. Some teflon tape to seal threads, permanent fix.
Probably cost less the 1 or 2 bucks.

 

[Dirtman]

Is that thing cracked in half or am I still drunk?

 

[Curious Hound]

Is that thing cracked in half or am I still drunk?

Optical illusion. Theres a heavy shadow from the rib around the casing.

 

[Dirtman]

Optical illusion. Theres a heavy shadow from the rib around the casing.

Ahhhhhhh now I see it....