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Discussion Starter · #1 ·
I put in a drain 0lug for my transmission pan.
Drill a hose, two nylon washers and tighten it type. 1/8 npt drain plug.
To be expected, it leaks.
Around the npt plug?, around the nylon gasket?, I don't know.
Anyone ever have any luck with these things?
I tried a couple different npt plugs, they barely fit. The one that came with the kit bottoms out.
 

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I've used them before, never had a problem. I have noticed though, the quality of "offshore" pipe threads has gone way down over the years. Bottoming out means the threads were cut too deep or of the wrong taper. Might try cleaning it up and doping the threads?

Russ
 

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Discussion Starter · #3 ·
The plug that came with it bottoms. Other, better plugs barely start. Perhaps I do need to run a tap into it a bit.
Good idea, thank you.
The transmission is drained, not a big deal to try.
What new gasket material would you try for the part in the pan? A plain washer with crush washers on either side, Rubber inner tube, thick hard gasket roll stuff?
 

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First lets see if were talking about a low cost factory like pan.

If that is the case I would just buy a $30 ish pan with a drain bolt built in.

Or upgrade your pan to a thicker style. Buy it once and be done pan after reading reviews etc.

If you are dealing with a "special" pan that is deeper or made of stainless/aluminum etc then I would tig weld a bung in.


Spending $20 for a bung(shipping) then another $20 have it welded(thats cheap) into a common $20 stockish pan having $60 invested in a stock ish pan that you can drain.

Or you can buy the same pan with a bolt built in(after reading reviews etc) for around $30 and bolt it up faster then you can get the bung to your door.

My butt is getting that stockish $30 pan with bolt welded in to my door within 3 days (amazon for free shipping/faster) without a 2nd thought and that leaking pan going into the scrap pile.
 

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The kits I'm familiar with had heavy white nylon washers around 3/16" thick and they sealed well as long as you remembered to use a backup wrench when removing the plug so the sealing interface wasn't disturbed. They have nicer ($$$) options out there:



Russ
 

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I make my own drain plug, really simple. 3/8 bolt and nut. I take a grinder and grind the six square sides off the nut until it is round. Drill a hole in the pan where the factory would have the drain plug. The rounded nut on the inside, a 3/8 bolt (3/4 inch long) bolted through the hole. Tighten down and then weld the rounded nut to the inside of the pan. take the bolt out, use a copper washer for the 3/8 bolt and you are done. Simple, costs about 50 cents.
 

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I've also thought about welding a castle nut on the inside. Castle portion down with good tacks on the corners and it will allow more fluid to drain before you drop the pan, at least in theory. I've not done it, so YMMV.
 

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Anytime I add a nut to thin material if it be a floor or the side of a oil pan (for a return line) I PUSH weld focasing the heat onto the nut and lay down 6 welds per side of the nut going 180 from the previously welded side and stopping every 2 welds to let things cool to avoid warping the thin material. Then (if possible) I weld the other side of the pan, etc.

I almost always place the nut 1/2 way above the material giving me plenty of area to push the bead against before squishing it down against the thinner on the slight pull back before pushing again.

Of course prep is important and if your using a nut then a file is your friend to make a nut like shape that the nut fits inside snug. Grind any finish or coatings off. Using a piece of threaded rod and a few nuts avoids bench grinding or burning your finger tips.

I usually just glob some gel on bolt threads and run a bolt down to apply the gel. I always clean up the threads after out of habit. Another reason to have the nut 1/2 way up is your not welding to the face of the nut so having the puddle fall into the threads is harder then if you were welding the nut face to a flush thin material.

I usually just do light tacks then grind the nut face when making the bolt flush relying on the weld on the other side of the bolt for sealing/strength. But placing them flush is really more for adding nuts to body panels at that point. Rivnuts are cool. But I still perfer to weld a nut when clearences allow for it.

Before you go running out to your oil pan. Grab some scrap and weld a nut or two into that scrap to set things up. Be mindful of heat when welding thin material to thicker and let things cool even if that means your stopping 4 or 6 times per side.

Once again 2 hours of prep and cooling time to weld a nut into old pan to replace a stripped nut where I can replace the old steel with a new pan for $30 pan is not worth it in my book. If your adding a return line in a oil pan then sure that is a cheap mod to place that return right where you want it. But if your talking about adding a drain plug to a stock TH400 pan then I would just buy a new shiny $30 pan.

I did a diff cover a while back on a 10 bolt when installing new bearings and seals. I just bought a new cover with fill bolt for like $20 vs messing around welding a nut in the old cover. Same deal. Just not worth the time to mess with it.
 

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Most bolt in drain plugs on transmission pans that i have seen either leak or the threaded side snaps in two.
 
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