Last weekend I was out on a trail in my 99 4runner. Got in a bad position in some rocks......long story short... I backed into a rock hard enough that it pushed the bolt in the emergency brake cable guide into the rear pumpkin and made a hole.

I can weld so my question is this. The diff oil level is just below the hole, is the best way to weld it up to drain all the fluid first and then weld it or vice versa?

I thought if I left the fluid in that it would protect the seals and there wouldn't be enough air for the oil to burn, has anyone done this?

Either way I will be completely changing out the diff oil.

 

I would drain before welding. You don't want to boil the gear oil anyway. Not to mention, if there was a hole you probably have some dirt in there that should be taken out.

 

isn't oil flammable and you are having a source of ignition near the oil
i would drain the oil, pull the axles and than the third...that way you can clean up the weld on the backside and don't get slag on your third...

 

Most of the time oil is only flammable if it's sprayed in a fine mist. I am with scuba, if you put a hole in the diff, I'd be taking it out and making sure nothing got in there that shouldn't be.

I don't know how to weld, but when you do don't you have slag etc flying around that could get into the diff while welding?

 

i do this kinda thing pretty frequently, i agree with ocdropzone, you want a clean weld. espcially if you want it to last

 

Drain the oil pull the rear!! to let the hot gasses escape as the oil cooks off.

Clean heat clean cook all the oil out of the area around your new hole If you have never done this you will be amazed how much oil cooks out!!

Getting a good weld is related to how clean you get the weldment

Just to be safe don`t forget to disconnect the negative battery cable!!

 

Thanks for the advice......... I was worried that you would say to pull the third. At least it's not my daily driver! I guess at least I will be able to finally verify what gears I have in my rear end . Anyone know where to get some good weld on diff armor?

 

If you have the time make your own!!

Good Luck

 

all-pro or trail gear.

 

Just another tip, you probably don't have to worry about it too much because you're not gunna be welding much, but if you take the third out and do a significant amount of welding on the axle with it out (such as adding diff armor), be careful to not let the housing heat up too much and let it warp. Like I said, you probably won't have to worry about it, but just keep it in mind

 

Pull the third, drain the oil, clean the housing with rubbing alcohol. DO NOT weld on a closed container with an oil residue. It can be explosive at worst and will definitely contaminate the weld.

 

Thanks for the help everyone!

I got the chance today to tear into it. It was going smooth until the very last bolt on the drivers side dust cover twisted off !!!!!!! Got the 3rd out and discovered I really do have 4:10 factory gears .

Anyway... it looks like that bracket on the back side of the diff that holds the emergency brake cable has metal legs that run parrall to the axle and held salt and crap and that is why the diff punctured so easy. I found another soft spot at the top around another bracket. Corrision sucks! Guess I weld it up and reinforce it with some plate.

 

Clean it up, then put some 1/8th or 3/16th plate over it, then hardface it maybe?