Rusted&stupid rear differential fill bolt

Hey community,
I wanted to change my rear differential fluid and the stupid fill bolt is rusted out to point where it’s socket size became bigger than it. Btw I didn’t drain it yet . So I’m good I got my old fluid there still lol.

 

25mm isn’t a common socket.
But 1” is the next size up that is common.

If it rounds off, a chisel or a welder is next.

BTW, that bolt head is “soft”.
Good luck

 

Should I use dw40?

 

Wd40, or better yet a penetrating oil can't hurt. Especially if you give it a soak and let it sit.

I would try hammering the correct socket (24 mm?) onto the bolt head first, before going to a larger size. Might have to chip off some of the rust first. The hammering should help break it loose, too.

Finally, since that nut is always a bitch, I like to use my hitch as a cheater pipe. The hitch has some weight to it (with a ball installed), and you can knock it / hammer on the wrench handle while holding the socket on the nut. Saves the knuckles and anything else if it gives way while yanking on it (or if it slips off the nut).

Goes without saying, you should go ahead and order a new fill nut now.

 

Penetrating fluid. Spray, wait 30min, spray, wait 30min, finally pray.

You can also TRY to use something similar to this if you don’t have a welder handy.

But if that fails, just weld a nut to the fker.

 

The best thing I’ve found is to take a big hammer and smacking the piss out of the bolt head.
That kind of “shocks” the bolt/rust loose. Ideally, you want the hammer head to be as big or bigger than the bolt head. If yours is stuck that bad, you might want to use a new crush washer gasket. But I’ve reused the old one with no problems. I’m 50% on using a new washer. Sometimes I do, sometimes I don’t.

This does not work as easily on the drain plug however.
since it has a guard around the bolt.

 

Had this happen on a prior rusty yota and the both the drain and fill nut started to round off. Used an Irwin 24mm bolt extractor. Both came right off. And that was a massively rusted piece of shit. Replaced both with new plugs.

 

I'd heat it up with a torch and soak it with penetrating oil. If you can get a something securely on it (socket/wrench) try using a bottle jack under the handle.

 

Probably the drain plug will be the same situation and size?

 

15/16" works too. That's what I always use and it fits well.
Clean the bolt head well and see if you can tap the socket on with a hammer.

 

Rear Diff Toyota parts (24mm or 15/16” head)
Case takes 3.1 qts gear oil
Drain plug with magnet #90341-18057 about $8
Torque 36 ft-lbs on M18x1.5 thread
Fill plug #90341-A0002 (old#18006) about $5
Torque 36 ft-lbs on M18x1.5 thread
Drain and Fill plug washers/gaskets #

$16 12157-10010 Toyota Oil Drain Plug Crushable Steel Gaskets Set of 10 OEM 12157-10010

12157-10010 about $1.50 each

Right 1/2 drive socket with a long extension first.
If not grab the head with a large pipe wrench and it will turn.

 

The last time I went to check my fluid level I cracked my self in the head with the breaker bar. I was expecting it to be “super” tight. So I yank the crap out of the breaker bar. Broke free knocked me in the head.