B/W Tranny dipstick plug help
 

I've got a couple of C72 B/W transmissions in a boat and the dipstick fill plugs keep wanting to pop back out after being put in. Got a C71 in another boat and it uses like a screw in pipe plug with a dipstick welded to the inside. Little harder to check the trans fluid needing a wrench to open but it's much more secure and never comes out.
Any ideas?

my c-72,s have a compression style dip stick.you insert,screw the t handle and it compreses and seals that way.

mine has a twist on top to expand the seal as well to lock in

We found that the stock nipple normally has a big burr on the end that chews up the rubber on the dipstick. Or maybe it is there on purpose, in any case we clean up the end and then put a groove in the ID to give the rubber something to hold on too.

bc and ez, that's the way mine work. Unscrew it as far as I can (without hurting the rubber) then push it in as hard as I can and tighten it down. It stays but don't take much to jar it loose and the last thing I want is an open trans fluid fill while out bouncing around.
M, Now I have done that around every pipe that I had to hose clamp a hose to for just the same "bite" reason. Never thought about doing it inside. Thinking my dremel will do it. How hard was it to get the pipe out of the transmission? I'm thinking its easy or you are going to have future issues after you screw it up. Also I wonder if that pipe's thread is the same as the 71's now that I look at it. I like their plug much better but if it is not the same I'm thinking I could make one like it but the right size with a pipe plug with a dipstick welded to it.

It's in there pretty tight. We made a tool for them. You can also use an internal pipe wrench. The thread is 3/4-NPT, same as 71 series. I don't think a Dremel is going to do what you need.

now here is one thing...those trans are setup to run withe either engine rotation, but they switch the filler with the vent when they run the other direction...just info..

Ez, it would make sense if they did that but they didn't. The pump indexing is switched but the filler and vent don't move. There is basically only 1 casting.

Ya, you just pull the couple bolts out of the front and flip the pump over for a reverse rotation motor and put the bolts back in. Nothing else changes. One of the transmissions I'm running now used to be on a r/r motor so I've done it