Richard S

I'd like to change the fluid in the differential on the auto tranny in the 79 shark. I attempted to loosen the upper fill plug first, but it didn't want to budge. The 17mm hex bit didn't seem to fit very snug, and I didn't want to break/strip anything before checking here first.

So how can I safely remove this plug? Any ideas are appreciated.

Also, I have a gasket for the whole rear diff plate. I had planned to remove the small bolts and remove the plate (to get a look at everything and clean it), but I will still need the fill plug removed in order to refill. Would it be easier to do this, and any suggestions on removing the fill plug if I have the plate off? (put in vice, use long breaker bar? can this harm the plate?)

Thanks in advance...

Rich

MikeN

Mine was really tough also. I put a bit of penetrating oil on the plug, let it sit. Then used a toothbrush to really clean the plug......getting rid of every spec of dirt, grease, etc. Then used a 2 foot breaker bar to apply very slow and even torque........it finally "popped" and unscrewed.

I have also seen people use a slightly larger non-metric (ASE) hex bit.....can't remeber exactly what size it is though..........and tap it in with a hammer, then remove as above. Some have had a small amount of heat work also.

It's really not uncommon to remove the rear plate as a lot of these plugs are seized (then try and coax the plugs out)......I've seen a lot strip upon removal also........with a resulting new rear plate and plugs needed. Good luck!

hinchcliffe

17mm = .669" SO A 11/16 would be slightly bigger. Make sure you clean out the hex hole good. Mine didn't feel deep enough so I squited a bunch of brake clean in there and low and behold the hole got a lot deeper. A 2' tube on the end of my breaker bar and I was good to go.

lorenolson888

I used a 17mm bid allen "drain plug tool" from craftsman (sears)

and a peice of metal pipe about a foot long...

pentrating oil works as well as a striking the tool with a hammer if it has been in for 7 years like mine was...

Oh yeah and you may as well bite the bullet and replace the drain plug if it is halfed stripped like mine was...

LO

Garth S

I've used the trick much as Mike noted. Soak in Kroil/PB blaster and with the tool fully inserted into the well, give a sharp blow with a hammer - keeping in mind the strength of the cover. The shock wave generally frees the corrosion.
Place a wrap of teflon seal tape (plumbers stuff for water pipes) around the threads before reinserting. This is also the trick for the block drain plugs.

mark kibort

if it sticks out, big vice grips work. (but destroys the bolt)
Ive had one in my 84 that we had to weld a hex on it, and use a socket to break it off

mk

Greggles

You might try a little heat or shocking it with an impact gun. BTDT and ended up buying a new rear cover (5 spd). Why does everyone torque these bolts to 250ft/lb ????

jyoon

would drilling a large hole through the middle loosen it up?

Oldtee

Old trick. Try to tighten it a little. Not much, just to move it. That breaks the crud on the threads and often, not always, fasteners will come out. Old aviation trick when dissimular corrosion sets in between steel fastners and aluminum.

Richard S

Thanks for all the ideas, I'll give them a try tomorrow and report back.

Rich