So, my project truck is a 78 F100 4x2, but built so late in 78 (specifically, August) that they used some 1979 parts. In this case, the T18 is the over-and-down-reverse that they apparently switched to for the 1979 model year.

That's besides the point: she leaks. Oil all along the bottom of the transmission. Drips from the front of the T18, the clutch bellhousing dust plate (I think that's what it's called), the transmission to extension housing, maybe the topcover... At least, that's where I think it's leaking from, through what appears to be 42 years of crud, oil, grease and road grim, 1/8 to 1/4 inch thick in places.

I figured it was seals. So for the first time in my life I have now pulled a transmission and I think I found the source of the problem: Gaskets? What are those?

I drained it, pulled the top cover and... huh, no gasket, just some really thin RTV gluing it down. Pulled the tranny all the way, flipped it over to clean the crud off (engine cleaner, plastic putty knife and a nylon brush), and found what appeared to be more RTV around the PTO, but not the input bearing retainer or extension housing. I pulled both of those and no gasket. Barely any RTV, and that not even all the way around. The only bit of gasket material I found was about 3/4 of an inch wide on the input bearing retainer. The seals themselves actually look okay, but since I'm already here I'm going to replace them anyway.

This is the first time I've ever done this so it may just be my lack of experience, but I'm not crazy, right? There should be gaskets? I do know they make them, and they do show up in T18 diagrams. Further question: anyone know the torque specs for the top cover, extension housing, input bearing retainer or reverse switch?


A view from the top before any cleaning

Partially cleaned on top


You can see where the oil drained down

So very cruddy

The end of the extension and housing, which is a seal

A: no gasket or sealant. B: that's a lot of crud around the speedo gear hole. C: no clue what blocking the drainage hole, but it still had gear oil in it.

Partially cleaned


Cleaned it up and found a message from the boys at the FoMoCo plant. Or the Borg-Warner plant, whichever.

On the upside, if that leak coming from the front of the bellhousing is due to this, that means I wont have to change the rear main seal! It's a 2 piece and I already did the front end of the engine and the oil pan gasket a few months ago; I have no wish to drop the oil pan again so soon. Either way, the bellhousing and clutch are getting pulled to check (maybe tomorrow)

 

Here's the lone bit of gasket I found, at the bottom of the picture

Well, pulled both seals and might have messed up the front bearing retainer; thing was practically welded in there, even with soaking it in wd-40.

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I think this happened when the plastic putty knife I was using as a buffer to keep from marring the rim while prying slipped, but I'm not sure; I didn't notice until after all was said and done. What do you think, saveable?