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Stripped Diff Drain Plug :( Thoughts?


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I went to change the rear diff fluid.  I followed the good advice I found here and opened the filler first.  Opened just fine.  In fact even a little fluid came out.


I went on to remove the drain.  Cleaned the crud out of it, but the hex socket wouldn't seem to go in quite far enough.  Check the depth with a screwdriver, nope it wasn't going in far enough.  Tried tapping it in with a hammer, then 'tapping' it in.  Got it as far as I could.


Yup it stripped.  I was yarding on it as pretty hard.  I'm sure it was partially stripped before I started.  It was pretty tight.  I'm not a big fan of these.


So, now how do I get it out?  I'm OK with destroying it to get it out, as they seem cheap enough.


my first thoughts were


1) chisel and a hammer and try and tap around the edges to spin it out.  Possibly zip some slots into it (outer edge to center) for the chisel to grip better.


2) weld a nut to the bottom and hopefully get good enough penetration to be able to take the torque.


Things are a little greasy underneath (I'll stop by the car wash and see how much I can get off), so the sparks from the grinder or the welder make me a little nervous.


Any one had to do this?






p.s.  Hope it isn't cross threaded, because that sounds like a lot less fun to fix.

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Ya know its not too difficult to just pull the diff out entirely and get at it better on your workbench, or at a machine shop, or just to dump all the old fluid out the fill hole.  :)

It's just 4 bolts on the driveshaft, 6 holding the diff, and a bunch of bolts on the axles (make sure you put loc-tite on them and tighten them to proper spec when you put them back).

Often times for stuck bolts that require hex tools, I use a slightly bigger torx tool if there's one available (might be difficult to get one that big).  They do dig in better than a hex tool, though. 

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I have had the same problem different car though, here is what I did.  short term (because it was my daily driver and could not find the bolt to replace the stripped bolt that weekend) was I made a pump from the diff bottles.  I attached a flexible rubber hose to the end that normally goes in the bottle and then the hose that is on the other end I just put into a container. Pumped out all of the fluid that was in the diff and replaced it with new fluid. the sealed it up. When I finally did find it and had the time to fix it (two weeks later with my schedule!) I cleaned the sht out of it and welded a bolt to it and got it off that way. A little fluid drained out, but i had the new one right there to replce super quick so i would not loose to much. Topped her off and then called Bob my uncle... Hope that helps..

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...........sounds like its time to upgrade to an LSD.



Say to your wife (or signifgant other): "Oh Babe, this stupid bolt is stripped and now stuck.  I really need to be able to change out the fluid on a regular basis and since it looks like I'll need to replace the dif, I'm going to upgrade to an LSD.  Shoud not add to much to the cost I am going incur anyway. Oh look I just located and LSD on the fourm, how's that for luck. Thanks Babe."

Edited by vinntagejoe
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My brilliant Grandpa Huber (farmer/school teacher/all around smart guy) used to use this trick on stuck machinery bolts. He'd heat said bolt with a torch (assuming bolt was in a safe/non-flamable situation), and then hold an unlit candle up to the heated threads. The heat would cause the wax to wick into the threads, causing them to loosen. Great trick. I've used it several times getting rusted down-pipe bolts to loosen up. 

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Since you already have somewhat of a shaft in the bolt (female hex head bolt right?) you could try using a bolt extractor. It might bite enough that it will turn.

I would be hesitant to drill as you could introduce metal shavings to the inside of diff- but knowing the length of the bolt you could just put some tape on your drill bits as a marker for drilling depth. You can also get some reverse direction bits and cutting oil at Harbor Freight for very little.... Sometimes the reverse bit will bite and back the bolt out. Just step up in bit size to where you can properly feed in your bolt extractor.

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