In the past when I had a stuck fill plug, I resorted to jacking up one side of the vehicle as high as I could, pulling an axle, and dumping in whatever amount the book said it took. Not an elegant approach, but can work in a pinch. On one truck I was able to pull a speed sensor and pour it in there.
Differential Plug Stuck, Stripped
- Thread starter Chuck61
- Start date
I'd try cutting a slot in it, applying a good bit of heat and hit it with a chisel, as suggested above.
If you get it out, check the threads and convert to a external bolt head plug.
First thing i did on my mazda , was get rid of the internal 8mm hex oil drain plug.
If you get it out, check the threads and convert to a external bolt head plug.
First thing i did on my mazda , was get rid of the internal 8mm hex oil drain plug.
I was thinking of doing that. It’s a M18-1.5 bolt, I believe.
I know it would make an unholy mess, but otherwise, why shouldn’t I take the cover off before removing the drain plug? I’m just curious. Would it damage something?
Whatever you do with the plugs put a bit of antisieze on them before they go back in.
My Sienna had a tranny drain bolt like that. You have to make sure the bit is fully inserted and flush at the bottom of the hole before applying any force to it.
My Sienna had a tranny drain bolt like that. You have to make sure the bit is fully inserted and flush at the bottom of the hole before applying any force to it.
I guess he's concerned that other damage might happen to the cover. Regardless of what you do is the car in a garage where you won't get other crud blowing into the diff it it stays open for a while?
It will probably be easier to remove the bolt with the cover still on the car since a cover that is removed will be moving around unless it's In a vice (but it could get further damaged or cracked) if you are wailing on the diff cover.
I know you are laying on your back etc. If you try to remove the bolt while the cover is off the car, I would some cardboard (maybe some pizza boxes or something similar) under the cover to prevent any possible damage.
If you drain out the old fluid how are you going to put in new fluid if the fill plug can't be removed ? You wont be able to drive it and will have to have it towed to the shop if your not able to remove it yourself.
The car isn’t garaged, so I’d likely cover the Diff with a plastic bag and secure it with a bungee.
I figured to remove the bolts, I’d screw the cover to a piece of 2x6 kd, which I would then clamp to my workbench. I’d like like to avoid screwing directly into the bench, but I could if necessary. I figured this would allow me enough room to use the 6 ft cheater bar I use on the lugs when rotate my tires. It makes popping off the lugs (89 ft/lbs) incredibly easy, I thought it would work on the stuck drain plug.
I wrote earlier in the thread that if I couldn’t get the fill plug out, I’d drill and tap a new fill hole.
I hope you don't need a pipe that long to get it off. Did you buy the car new?
I did buy it new. I feel like I’ve maintained everything else, but honestly I was only sort of vaguely aware that the differential oil needed to be changed. I’ve only previously owned commuter sedans that did not get the workout that the Forester does, so it wasn’t on my radar.
Thanks for all the suggestions everyone, you’ve given me a lot to think about. It might be a little while before I can get back to this, but when I do I’ll repost and hopefully have pictures if I do decide to try to make the existing cover work.
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I was just wondering if someone put loctite on the plugs. If you have a propane torch would heat it up a bit before trying to loosen it. Good luck and keep us posted.
In that case, heating the bolt with a propane torch (and allowing to cool) before removal would help.
Rock auto may have one. Anyway, yes to the propane, let cool and spray it with liquid wrench. Put some vise grips on it. Hate to ask you but are your turning it to the left? I've seen guys get confused when they are lying on their side underneath the car. Also, do you have a pic?
Let us know how it works out for you. 
I would use the chisel method. If that didn't work, I would try an extractor.
If that didn't work, I would remove the cover and take it to a local auto machine shop.
A little anti-sieze on the way back in might be a good idea?
Good luck. Have fun with it!
If that didn't work, I would remove the cover and take it to a local auto machine shop.
A little anti-sieze on the way back in might be a good idea?
Good luck. Have fun with it!
It’s the fill plug that is stripped.