John deere 350c dozer leaking cotter pin?

[JaysonJocelyn2022]

Keep having to add transmission/final drive fluid in my 1976 john deere 350c dozer. Leaking fluid from cotter pin hole on the reverser casing. Anyone know where that’s leaking from and what’s the function of the cotter pin. I’ve attached a photo. Thanks.

 

[Jim.ME]

Keep having to add transmission/final drive fluid in my 1976 john deere 350c dozer. Leaking fluid from cotter pin hole on the reverser casing. Anyone know where that’s leaking from and what’s the function of the cotter pin. I’ve attached a photo. Thanks.

The cotter pin is a "jiggle pin" to keep the hole open so any oil leaking from a rear main or transmission input seal or gasket does not build up inside the housing. You need to pull the engine to get to the transmission pump/shaft seal(s). Did you purchase the technical manual (JD publication number TM1115) for your 350C?

 

[JaysonJocelyn2022]

That sounds like a pretty large job, thanks for the info. Yes, I’ve purchased the manual

 

[Jim.ME]

That sounds like a pretty large job, thanks for the info. Yes, I’ve purchased the manual

Separation section will tell you how to get there and powertrain section will give you an idea of what you need to do.

 

[Russ from MN]

We had that happen a few times, the engine would start at -30F, but the transmission seal would blow, we got pretty good and pulling the engine. You need to make up a 3/4 extension about 4 feet long with I think a 15/16 socket, maybe 1 1/8. You have to pull the front cowling, but the radiator stays in place, no draining the coolant. Unhook the hydraulic lines and the electrical, reach in from the front with the long extension, there are 4 bolts holding the bell housing to the transmission. We had a Farmall M with a good Johnson loader to remove the engine. I haven't done it in over 50 years, but I bet I could do it in 8 hours, but I'm not for hire! Wrap the splines with electrical tape before sliding the new seal over them, the splines may be sharp and scratch the seal. good luck, let us know the results!