transmission problems

[wallyw]

I just bought a FLU419 "Unimog" at auction and was wondering if anyone knew of a mobile mechanic in the Denver CO are. This truck has a loader on the front and hoe on the back. It has a manual trans, but none of the gears in it work. I can engage the PTO and it works properly. We jacked all 4 wheels up off the ground and in 4x4 they would all turn. They would also turn with the engine revved up and in gear, but you could stop them buy hand. Any help would be appreciated.

 

[tommys2patrick]

Don't know much about Mogs but it sounds like it might be the clutch. Does it feel like you have good clutch pedal action?

 

[Jeepsinker]

That won't be transmission, that'll be either clutch, or some kind of safety lockout maybe malfunctioning. Make sure the rear shovel isn't engaged at all. I don't think the truck is supposed to move without it stowed or at least locked out.

 

[Katavic918]

I'm with jeepsinker on this. If something mechanical was wrong such as a gear problem, you would be completely disconnected from the drive train. If your clutch was completely smoked like someone had just held it to the wood with it slipping for an hour, then it could be a clutch. But yeah it more than likely sounds like an interlock is disengaged having to do with the rear shovel.

 

[wallyw]

Don't know much about Mogs but it sounds like it might be the clutch. Does it feel like you have good clutch pedal action?

The clutch feels ok. It starts and stops the PTO as it should, the shovel is up and in locked position.

 

[Jeepsinker]

If you can run attachments under load with the pto engaged then the clutch isn't the problem. Just because the shovel is stowed and locked doesn't mean that there isn't a failed interlock mechanism screwing things up. Most vehicles equipped with pto driven equipment have lockouts that prevent movement of the vehicle while the pto is engaged. Firetrucks and wreckers to name just a couple, and that includes military wreckers. Some work by engaging the vehicles air brakes, and some disengage the vehicles drivetrain. Sounds like yours is the latter. All you need to do is find out what is sticking or broken off or bent. Whatever it is will be small. You may even find that there is just some linkage misadjusted.

 

[wallyw]

Would the interlock be on the shovel or on the PTO?

 

[patracy]

Moved to unimog section.

 

[profo]

Are you sure sure you have the 1-4 gear selector and the high/low/ reverse selector engaged because you can have two neutrals if both are not selected also double check the 2wd/4wd/4wd diff lock switch is selected and not in between selections also, the truck will drive with pto's engaged there are no lock out positions. Also double check the intermediate switch on the 1-4 shift to make sure you have it all the way up or all the way down you can tell by when engine is running when you flip switch and press clutch you will here the transmission shift by itself.

 

[wallyw]

I have made sure the small gear stick was in 1-2 or reverse, have tried all the gears on the tall stick, and have switch from high to low with the air operated selector for high and low(can here the trans change). Have also tried the same thing with it in 4x4. Nothing has worked. At times it will creep forward about 6 in then nothing. PTO work well with the clutch. I've put it in gear and let out on the clutch and revved the engine and it has not produced any smells or smoke.

 

[Jeepsinker]

Maybe you have a sheared shaft somewhere. Does it have a divorced transfer case? I've yet to crawl under one. At this point, I would drop the rear driveshaft, with the transmission in gear and the transfer in 2wd, then put a large pipe wrench or similar tool on the output flange and see if you can turn it freely, or if it turns the engine. If you pull the driveshaft and the output flange on the transfer case falls off onto the ground, then you've found your issue. The transmission output shaft could also be sheared, but that isn't nearly as likely. Some transfer cases also have a viscous fluid clutch inside that can fail and cause this symptom too, but those are only found in vehicles with full time 4x4. Of course, like I said, I've never worked on a unimog.

 

[Mercunimog404]

Unimogs do not have a separate transfer case. The tranny and transfer case are one unit. Maybe the OP should go on benzworld.org. There will be a lot more knowledge on that site.