Stripped transmission drain plug - Ford 4100

[fried1765]

I bought an 80's Ford 4100 diesel a couple of years ago and I need to change the transmission fluid. However the plug is stripped, so I can't get it out. It's the type with an inverted 1/2 inch square which was almost completely rounded. I couldn't get any bite with my 1/2 breaker bar so I ordered some extractors. The plug seems to be soft metal as the extractors seem to get a little bit of a bite and then just start eating away material.

I'm not sure what else to try, I was going to try and collapse in the sides so that the threads would be loose but it sits almost flush with the transmission housing so I can't really get much forse from the outside.

Any suggestions?

I would thoroughly clean the inside of that square socket with lacquer thinner.
Then use the proper sized very short socket extension (1/2"?), and epoxy it into the square plug, with either MarineTex, or JBWeld.
You will destroy any future use of the short extension, but will most likely be able to remove the plug.

 

[ruffdog]

Tap drill for a 3/4-14 is a 29/32" drill. Depending on how well you get a 1/2" drill centered in the plug, I would then drill it to 7/8" and pick out the remainder of the plug, clean threads, and install new plug. If you are off center, you can still stay undersize so you don't damage the threads, then tap out the remainder using a punch.

 

[Other Bob]

I was thinking of welding a bolt or socket extension like suggested but pretty new to welding, not sure how the weld would do with a chrome or nickle plated object. Tried the old welding a nut onto a bolt that was broken off below the surface a while back with no luck, assumed it had to do with the fact I'm using flux-core and there was too much slag in the nut to get a good weld. I'm probably just overthinking this...

 

[WranglerX]

I was thinking of welding a bolt or socket extension like suggested but pretty new to welding, not sure how the weld would do with a chrome or nickle plated object. Tried the old welding a nut onto a bolt that was broken off below the surface a while back with no luck, assumed it had to do with the fact I'm using flux-core and there was too much slag in the nut to get a good weld. I'm probably just overthinking this...

Grind/sand chrome off extension before weld.... Might try the epoxy trick first but I have doubt it will have enough bond strength even after curing for 24 hours to come to full strength...

I moved to solid wire and shield gas (GMAW) along time ago so I did not have to deal with slag.... But fluxcore (FCAW) still has its places...

Dale

 

[Industrial Toys]

I did an oil change on our tractor this summer and encountered that type of plug. To my amazement I could not move it with a breaker bar. How can that be, if it's put in wet with oil? It was starting to cam out!

Anyway, I seem to recall, that against my better judgment, I heated it or the surrounding area with just a propane torch and it came out like nothing. So, I would heat that plug, prior to trying an extractor.

 

[fried1765]

I did an oil change on our tractor this summer and encountered that type of plug. To my amazement I could not move it with a breaker bar. How can that be, if it's put in wet with oil? It was starting to cam out!

Anyway, I seem to recall, that against my better judgment, I heated it or the surrounding area with just a propane torch and it came out like nothing. So, I would heat that plug, prior to trying an extractor.

Maybe just use a pencil flame propane torch to heat just the plug itself,...then let it cool, and try removal.

 

[Industrial Toys]

I think that is EXACTLY what I used. I don't have much experience with those square drive plugs and thought they would be the cats meow, but a ratchet doesn't exactly fit tight in them, ratchets are rounded, and the Deere Plug seems quite soft!

 

[CoyPatton]

Tap drill for a 3/4-14 is a 29/32" drill. Depending on how well you get a 1/2" drill centered in the plug, I would then drill it to 7/8" and pick out the remainder of the plug, clean threads, and install new plug. If you are off center, you can still stay undersize so you don't damage the threads, then tap out the remainder using a punch.

If your plug is 3/4”=6/8” how can you you stand undersized at 1/8” over the plug size? I believe there is some math error going on!

 

[Industrial Toys]

Just curious, what style of extractor you tried? Kind of what the average person doesn't have, but a large reverse tap, might work better than an extractor. Heating the area first a bit.

How are you dealing with the oil, when drilling into the plug?

 

[ruffdog]

If your plug is 3/4”=6/8” how can you you stand undersized at 1/8” over the plug size? I believe there is some math error going on!

Check the chart.....

TAP DRILL SIZE CHART FOR NPT THREADS