C-2 Stuck Diff Plug

[Chris R.]

I'm a relatively new owner of a 64 convertible. I'd like to change the diff fluid since I don't know when the last time it was changed. My problem is that the plug is stuck. I've tried getting it with a crescent wrench as well as a pipe wrench. I've thought about removing the spare tire tub to try to get more leverage. Is there an easier way? Is there a tool I need? I'm starting to round off the plug. I even think a piece of the plug broke off. A previous owner sprayed the entire engine compartment and undercarriage with black paint to make it look nice but all it's done is goop everything up!

Last night I sprayed the plug with anti-sieze and will probably do it again tonight. While I was at it I also tried to loosen the transmission plug. Same result - Stuck.

Thanks for your advice.

Chris Rose
#31220

[Wayne P.]

Re: C-2 Stuck Diff Plug

You need a socket and extension and a flex handle. I haven't run across one yet that this wouldn't remove. You can't get enough leverage with the pipe wrench.

[John H.]

Re: C-2 Stuck Diff Plug

Sears has 1/2"-drive 8-point sockets that are terrific on square-head diff and trans plugs, especially with a breaker bar.

[Jim T.]

Re: C-2 Stuck Diff Plug

I don't have any magic method to remove a difficult rear end plug that has started to round off or a possible siezed transmission plug. When I was about 16 working in a full service gas station I taught myself a very good lesson. I checked a customers rear end while the car was up on the lift and the oil draining. Not knowing better I tightened up the rear end drain plug to tight it broke. The threads were still in the rear end and my only thought was that I had created one heck of a problem. Got my boss and showed him what I had done. He kind of smiled at me as he reached up and backed out the threads from the differential and told me not to put the new in to tight.
You may not want to do this, but to give plenty of room, you should probably remove the rear spring. This will probably give you straight line access to using a a cold chisel and hammer and try to break the plug loose using the large shoulder of the plug and replace the plug with a new one.
I once had a transmission plug that was siezed in a 4-speed Muncie. After rounding the plug I removed the transmission and carefully drilled it out, always cleaning the cut metal and the final stages using heavy grease to capture the cuttings and eventually getting it out. This plug had not been removed for several years. A professional would probably have a better procedure.

[Rob A.]

Re: C-2 Stuck Diff Plug

Plain, old brake fluid works great to loosen stuck and/or rusty bolts, etc. Even better than liquid wrench, etc., which won't dissolve the paint that might be helping to keep the plug stuck. Brake fluid will dissolve the paint as well as any rust all at once. If you use the other various solvents you'll have to remove the paint first in order for them to work. (Try tapping lightly on the plug after you use it and while trying to turn the plug).

[Tom Merkel]

Re: C-2 Stuck Diff Plug

I just went thru this same ordeal, although mine wasn't stuck too tight. Someone suggested an 8-point socket, hammered on gingerly. That's what worked for me. Good luck.

Tom

[Chuck R.]

Re: C-2 Stuck Diff Plug

Sometimes we get all hung up on reefing on bolts and nuts and most times end up in this position. I have learned the hard way that a good steady pressure against a bolt/nut with a slight "bouncing" action can start many frozen pieces.

Patience though is key, it might take more than a minute or two of this pressure/less pressure (bouncing I call it) to get results. THEN if the bolt/nut does loosen, stop and start applying penetrating oil and tighten it back down allowing the oil to travel along the threads and then slowy work the bolt or nut free. This tightening/loosening process while applying penetrants will avoid the dreaded snapped off bolt with a nut half way off if you don't use a lubricant.

If you have rounded off the plug so as a socket will not hold, try lightly grinding/filing the surfaces down to an in between metric size and try again with the breaker bar. Again steady pressure and a good square fit on the plug is key.

These cast plugs tend to be brittle and being hollow on the back tend to break off leaving the thread body still in the housing.

This is how I dealt with this type os issue deaking with cast pipe fittings.

Sometimes a plug breaking off can work to an advantage as the stress on the threads is sometimes relieved allowing for easy removal. Other times what I have had to do is drill through the head stepping up in size until I get close to the inner plug thread body. I then would use a hacksaw blade cut into the plug body carefully making sure that I didn't go too far and nick the threads.

What this does is takes some of the holding strength (bite) away from the threads and relieving the strain. Then it's a matter of either caving the plug body in (Imploding) by using either a drif or small chisel, or trying to tap the plug body to try and get it to back out.

I always make three cuts spaced in thirds but test each one as sometimes you casn get lucky and it might start after the first.

Of course after all of this it will have to be taken for granted that there will be contaminents in the housing.

Sorry it's so long winded, theres no better way I could explain it.

e-mail me with a phone number if you want to talk about it in furhter detail.

Plumber Rice

[Mike M.]

Re: C-2 Stuck Diff Plug

i use a snap-on crow's foot wrench on a long 3/8" extension and a long handled 3/8 ratchet. mike

[Chris R.]

Re: C-2 Stuck Diff Plug

Thanks for all the responses. I found an 8 pt. 3/4" socket at Sears. Fit like a glove. After the penetrating oil and the right tool, the plug loosened with one little tug! My local Chevy dealer had started to round off the plug and insisted that they were gonna have to drill it out. Glad I followed my instincts and went to the experts - NCRS. The best $30 I've spent on my car yet. You guys (and gals) are great!

Thanks,
Chris