'59 Plymouth Forum

Any tips on how to remove the drain plug on the bottom of the pumpkin on rear axel?

I have not seen a drain plug on the 8.75 rear axle. it may have been added for an aftermarket flush kit. For tapered pipe plugs I have found a few good raps with a hammer and some penetrating oil, followed by Brute Force and correct size plug socket.

It's a factory drain plug. It's on bottom of pumpkin about 2" off center toward passenger side. I have two rear axels on the floor of my garage right now and they both have it.
It's not a plug like the add plug. Unfortunately it won't take a normal socket or a wrench. Don't know proper name, but it's a plug with a square recessed hole. The end of a socket adaptor, ratchet head, or a breaker bar end would fit in that hole if it was a 1/4" or 3/8" hole but one's too small and the other is too big. It might take a 5/16" square piece of stock but I'm thinking the piece of stock might be too soft of a metal. That plug is really in their.
One thing I might do is take a 1/2" to 3/8" socket adaptor (harder metal) and grind the 3/8" end down to where it will fit snugly into hole, then use an impact gun on it.
What I found to fit in hole is the square key from the end of the axel shaft, but it's a hair too loose and starting to round off inside corners of plug a bit. A 12 pt closed end wrench or 12 pt socket actually fits onto that key so a guy has a handle. Been tapping on that "handle" with a hammer, but like I said, the key is a tad too small so have to go another route.

Been soaking the threads around it with PB Blaster now for 2 days. My mechanic buddy suggested heat but that housing is pretty thin metal I think. I'd probably end up burning a hole through it.

The drain plug square hole on the old axle I am replacing is all distorted. It almost looks like a torx fitting, so someone must have had the same problem I'm having on the replacement axle. (sorry for the long winded post)

Otherwise I guess I'll have to drain it through the add plug, but they say you never get all the old oil (probably 53 years old) out that way.

Not a hex wrench fit? I sold my service manuals to John Quinn, so I can't supply an answer..

Hi Roger - No, not a hex. A square recessed hole. I suppose I could check my service manual. Never thought of it. The metal in that area is pretty heavy stuff so maybe heat will be a last resort. But the key is to have the right tool wrench or? I just don't want to round out that square hole.

Checked big book, no mention of drain plug. Misplaced '59 supplement.

I think Ron Keij has posted the 59 supplement here on the Forum in .pdf some where. Let me go look for it.

Here is the main parts manual link that Ron posted. It has both the 57-58 main manual and the supplement.

https://59plymouth.net/59gallery/thu ... p?album=77

John Q.

Not enough detail, as far as I can see. Need someone with first-hand knowledge!

If you strip out the plug, drill out the center and add a tapered pipe plug inside. I know it's not the answer you are looking for.. it does work. We won't be able to see it anyway. I have had to do these in the past on stubborn engine plugs. A plug that includes a magnet can be a benefit. Food for thought; We can not buy gear oil as good as what the factory used back in the day.

Good idea, Ricky, on the drilling out plug.
I did buy a short piece of 5/16" square stock and it fits good in plug. I cut a short piece off (about an 1" long) and put it in a 3/8" socket. Plug still won't budge and hole is starting to "unsquare" itself.

As far as things not as good as back then, I hear ya. Reminds me of a woodworking site I frequent. A lot of guys sell their old tools, saws, drill presses, etc., and then after using new one, wishes they would have kept the old.

I have used some light heat from a propane torch to hit the area to open up the rust bond between the axle and the plug and then hit it with a rust solvent like PB and do this a couple of cycles.

After, the 2nd or 3rd heat cycle, I then try to remove the plug while the plug is still warm/hot. If that does not work after that, then you will have to drill out the plug. Just my two cents...

John Q.

I have to drain all the cars that come into the yard,[1000 currently], so I bought a good set of the square plug sockets from Snap-On. The 5/16" one is the correct one to use. Sometimes, by tapping the socket as deep as it will go into the recess, you will find enough good metal in the plug to extract it. If not, You can weld a short 3/8" bolt to the plug and use a 9/16th socket to remove it.

---John

Got it out. Applied a little heat from accel/ox torch and it started to turn. Squirted a little more PB Blaster on it and she turned right out. That 5/16" square stock piece attached to a 3/8" 12 pt socket worked. Could not find square plug sockets locally.

Outstanding! Our work is done here! We are standing by with additional Tech support as needed!


John Q.

Thanks John, thanks everybody for your comments/advice. I'm replacing axle because of vibration. Just hoping it's gone when we're done. Checked everything else (u-joints, motor mounts, e-brake drum, tranny, tires) found too much play in old axle. Parts axle is nice and tight, and hopefully won't leak like the old one.