Newly acquired '88 F450 superduty 7.3 5 spd..stuck in second gear!

[Seanable]

Greetings. I have a 1988 Ford F450 dually 7.3 IDI with a 5 speed. The five speed is either a ZF S5-42, or a ZF S5-47. I bought it with it stuck in second gear. The PO said he drove it to where it was parked for 20 miles stuck in second gear...which tells me the trans is not destroyed. It is 150 miles away and I am trying to fix it and drive it on home so I dont have to rent a trailer and haul it home. Upon removing the shifter, and pulling the top plate off I discovered it was filled with gear oil. I know that is wrong as they are supposed to use mercon V synthetic ATF. After hours of watching videos and reading up I believe it might be a stuck syncro due to the wrong lubricant, or the shift fork jumped out of the groove it is suppoed to ride in. The 1-2 shift rod appears to be stuck in place. My question is...if I drained the gear oil out and filled it with ATF, then pushed to truck forward and backward, will it free up? Does anyone know a manner in which to get this sucker out of gear? Thank you ahead of time.

 

[chris142]

All the synchronizer does is gets the gears up to the same speed when shifting. Has nothing to do with it being stuck in a gear. A broken shift fork is a possibility.

 

[Seanable]

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Is it possible for a shift fork to get jammed? When I look into the top it doesnt look like anything is broken. It just feels like the 1-2 shift rod is stuck. I have gently pried on it and it dosen't seem to move at all.

 

[frankenwrench]

These are obviously rusted up from being kicked outside(1st, 3rd,4th and reverse were ground all the way out wen I got my first zf idi) for not having any gears but second and fifth that would move the truck just grinded alot. But the two slide rods my fingers are pointing at( I know I called it the wrong thing, but don't know correct name) in my second zf were gouged and looked like a rainbow like someone hit it with a torch at some point and the forks couldn't move cause they were swollen I guess and couldn't slide forwards or backwards. Idk if this is your problem, but it's worth a look. But bring some gasket maker or roll a gasket with you to seal it back up. Especially if u can free whatever up and get it shifting so u can scoot that truck on home!

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Also, there's a spring and a little piece of plate metal that's riding a brass (I think) piece. Wen removing the shift tower and replacing. Take note of where it is and ensure that it stays/returns in the same way u found it. Dropped the spring down into one once.... Got lucky and was able to drain it from the plug and the spring came out wit the fluid!

 

[Seanable]

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I saved the reverse lockout tab and spring. I can see the potential for it to fall into the void though. Heres a pic into the innards of my trans...nothing looks out of place or obviously broken. I am wondering if the gear oil someone put in it caused this problem...also hoping draining it and refilling it with the proper ATF will help. In the pic the shift fork with the "K" written on it is the one that is seized. Everything else moves fine.

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[DaveBen]

There is a possibility that the gear that the fork pushes is bound up. It could be many things like rust or... I would remove all of the gears and do a rebuild.