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New member with a question about Sherman transmission unit.

798 Views 13 Replies 4 Participants Last post by  Nouveau Redneck
Hi all, new member here with my first 'real' post.
I'm working on a "N" series Ford that has been in my family for about 45-50 years. My Dad always referred to it as a 9N, but I'm not sure, based on the stamped serial #.
It started leaking a lot of trans oil from the two 'jiggle' pins and affecting the clutch. I noticed a couple drips about 6 months ago and knew that I was going to have to split the tractor to fix it.
It got really bad last week and it seemed that it was much worse very quickly.

I split the tractor and was thinking that the input seal for the transmission was bad.
The tractor has a Sherman unit, and from what I've read here it is the combo unit with the lever through the side of the bell. There was a LOT of oil inside the housing so I could not pinpoint or positively identify the source of the leak. I pulled the input off of the Sherman expecting to find a torn seal but the seal was snug and was in great shape.
All of the mounting bolts for the Sherman were tight, the mounting adapter was tight (not cracked) and none of the gaskets or shims appear to be the cause.
What I DID find was a 3/8" hole in the top cover of the Sherman unit.

This tractor has never been apart since we've owned it so I don't know if that hole was leaking a little oil over a lot of years? I looked all over for a 3/8" cup plug but there was nothing in the bottom of the housing, no plug in the sump of the Sherman, no 'fuzz' stuck to the magnetic plug of the Sherman to indicate a plug got ground up.
It seems odd to me that this hole has been there 'forever' and it only recently started leaking...?

So, all this information to ask for opinions/advice....
I can install a 3/8 cup plug in the hole -or- I was thinking that I might tap the hole for 1/8 npt and install a 45* street elbow with a 1/8 npt axle vent if folks more familiar with these tractors think it might be wise. I have researched a few of these Ford N forums to see if I could find a picture of a Sherman top cover and almost all of the pics I could find showed no hole, no breather, no threaded plug. There was 1 picture (very low res) on ebay that showed what looked like a threaded plug but I couldn't be sure.
I'm attaching a picture to show the hole and it's location, I can't imagine how this has been open for all these years and only recently started pushing oil....but the indications are that trans oil has been contained everywhere else that I looked.

Any and all opinions welcome! Thanks in advance!
I do not do any of this internet stuff on my phone, normally all of this kind of stuff takes place at the end of the day from my home computer so my replies will not be immediate.
Let me see if I can post the pic...

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That hole on the Sherman is for a vent plug to allow things to heat up when the tractor is being used and cool down afterwards without air pressure building inside, as that might cause a seal to leak. Do not close it off completely. Get a replacement vent plug and install it. The part number is 01A7034 and it is still available. You should be able to get one from any New Holland dealer.
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That vent is sticking up above the top of the housing of the Sherman. I'm not sure how much clearance there is above that housing when it's installed into the bell housing, so make sure it will clear.
Look good.
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