So I was starting my rear diff oil change, and I got my lefts and rights mixed up from the angle I was laying under the car. I overtightened the drain bolt so much that it's twisted on itself. No leaks or cracks as a result.

I had already opened the fill plug and I was actually a little low on oil, so I simply added some more and put the fill plug back while I beat myself up over my stupidity.

Has anyone successfully taken an easy out to one of these plugs, cleaned/chased the threads on the diff, and just put on a new plug?

I'm sure (hoping) the bolt itself is a weaker metal than the housing, so hopefully the plug is just toast, but the housing is ok... I'm thinking I may used some blue thread lock, and see how it goes parked over a doggie pee pad for a while - if I can get the plug out.

Anyone here got any experience on how they faired in a similar situation? The dealer was going to go with a heli-coil retap, but we've had bad experiences with those backing themselves out at my work (not automotive).

You Doof!

If all else fails you could have somebody weld on another bung over top the old one.

I would leave the bottom broken drain plug alone. Then use a hand pump to remove the old diff oil thru the fill hole

Swap rear axles, better yet, time for a full part out! I'll take it off your hands

Excuse for an ECGS Dana 60.

If it leaks after getting the old one out, this may be the best option. Just drill out for a bung so that there’s no tapping for time-serts or helicoils. It would potentially stick out a little further than factory, but I could have a larger cover ring welded onto it too. Access to people with welding skills isn’t much of an issue, thankfully. I just try not to bother them.

Here is my experience with my '98 4runner (as posted originally on different forum)

Don't remove the drain plug until you are sure you can remove the FILL plug.

After changing driveshaft u-joints in my 4runner, I figured I change the diff oil while I was under there. Drain plug came right out along with the oil. But the fill plug wouldn't budge with a 1/2" breaker bar so I got the big impact. Rounded it off. So I got the the big Knipex pliers- wouldn't budge (but didn't slip- those things are great). Even put a cheater bar on the knipex and still wouldn't budge. No lift, no space to really crank on it. Had to get to work next day so I ended up drilling a hole next to the fill plug. I put a magnet on the case to try to catch shavings. I left a magnet on the bottom of the case to (hopefully) hold any shavings that went in at the bottom. I plugged the hole with quicksteel and called it good.
That kinda sucked.



Follow up:
4 years and about 100,000 miles later all is still (relatively) well. I was under there tonight bleeding the brakes and noticed a slight oil leak from the JB welded hole. Might be time to fix it better

As you know you need to get the fill plug out, there a couple of guys here that had issues with getting the plug break loose...until they decided to apply some heat to it and then it broke loose easily, heat works wonders getting a seized or rusted bolt loose, did you trying using a Map gas or propane torch on it?

I've gotten the fill plug loose and off, and I know I broke the drain plug loose already. The problem is that i just tightened it instead of loosening it.

I've already received my new OEM drain plug, so I'm going to length mark all my drill bits with tape to prevent drilling all the way through the bolt using the new bolt as a guide.

I'm hoping that I can use a set of bolt extractor bits to unscrew the bolt. Since it's not leaking, I'm assuming the housing isn't cracked, and I'm really hoping that I can just clean the threads and put on the new bolt if and when the old bolt comes out. Since the original bolt isn't rusted shut, just torqued shut, I'm thinking I've got a shot. I'll just have to drill deep enough that I'm actually turning the un-compromised section of the bolt.

Blue thread locker and prayers also required. Remaining parts are out for delivery, so I'll find out soon enough...

The axle housing is steel so I seriously doubt you cracked the housing. Worst case, you might have stripped some threads and ruined the plug. Unless the hex is rounded, you could probably get the drain plug out using an impact gun. Just replace the drain plug with the new one you have coming and don't forget to use a new washer on it. If the hex head is rounded, then welding a nut to the drain plug head and then using the impact gun would be the best bet to get it out.

What are you planning on using the blue thread locker on? Not following that part. Until you have the drain plug out, you won't know the condition of the threads in the housing.

The existing plug is absolutely ruined. It's not rounded off - it's torqued beyond yield - it's twisting on itself as you turn it either direction. I'm going to have to drill into it and use an easy out / bolt extractor just to remove it. The blue thread locker is just to secure the new drain plug to prevent it from leaking - if I can get that far...

Considering it'll be a couple/few years before I need to change the diff oil again, breaking free some blue thread locker can be a problem for future-doof to handle.

I've got new washers as well.

Don't rush in with the thread locker until you inspect the threads of the housing. Like I said, the housing is steel, I doubt the threads in it are ruined, just the drain plug threads. If the housing threads are intact, do not use thread locker, just install the new drain plug as normal and torque it properly.

Yeah I've got an m18 thread cleaner and an m18 tap to chase the threads if there's any damage to them. Thread locker is only there if the threads look in bad shape and have to be tapped or practically recut for the new bolt to thread properly.

Welp. I'm stumped.

I drilled almost all the way through the bolt and can set the extractor bit into the bolt, but the bolt does not unthread from the housing. It appears that the threads on the housing must be on an insert or something, and I must be spinning the bolt and insert together. If this is right, I'm going to end up leaking eventually, especially the more I unsuccessfully remove the bolt.

I may need to just weld it shut and do my fluid changes by pumping out the old fluid through the filler plug.

I could drill the bolt all the way out and weld in an O2 bung later. That or legitimately get a new axle down the road, lol.