FMTV hydraulic pump and Transmission

[eugenehanway]

Hello all,

I am new to the SS forum, I read a ton of the threads but this is my first post. I own an FMTV M1088 tractor and a M934A1 van truck so I am not a complete novice but am no expert by any means. My recent addition FMTV hydraulic pump will not stop trying to pump. I turn all the dials to the "straight up" position and you can still hear the pump actuating every so often. Is this normal?

I also drove the 1088 about 80 miles to our lake property and the transmission light came on and the transmission would only shift into 6th gear. I pulled the transmission dip stick and the oil is very clear so hard to tell but it looks to be overfull. I need to get it on more level ground and double check. It only happens when the transmission gets hot. Would the overfill cause the transmission to do this?

Thank you for any help or suggestions.

 

[Ronmar]

You need to read out the fault codes in the transmission. Press up and down arrows at tge same time. There are 5 memory positions D1-D5. It will flash D1 ?? ??(2 sets of numbers). Write the numbers down. Note if the mode light is lit. Press the mode button to step thru the 5 memory locations. Press both arrows again or shut off power to exit.

the PTO shouldn't be on unless you turned it on, are tou sure that is what is engaging? Any other sounds with it, like air being released?

 

[Mullaney]

Hello all,

I am new to the SS forum, I read a ton of the threads but this is my first post. I own an FMTV M1088 tractor and a M934A1 van truck so I am not a complete novice but am no expert by any means. My recent addition FMTV hydraulic pump will not stop trying to pump. I turn all the dials to the "straight up" position and you can still hear the pump actuating every so often. Is this normal?

I also drove the 1088 about 80 miles to our lake property and the transmission light came on and the transmission would only shift into 6th gear. I pulled the transmission dip stick and the oil is very clear so hard to tell but it looks to be overfull. I need to get it on more level ground and double check. It only happens when the transmission gets hot. Would the overfill cause the transmission to do this?

Thank you for any help or suggestions.

.
This is a M1088. Unless you added a winch to the truck (most don't have one) is it possible that you are hearing the hydraulics that lower the spare tire and raise the cab? A kind of "thunk-a thunk-a thunk-a" sound rather than a whirring sound like a PTO mounted to the transmission would make?

 

[wheelspinner]

.
This is a M1088. Unless you added a winch to the truck (most don't have one) is it possible that you are hearing the hydraulics that lower the spare tire and raise the cab? A kind of "thunk-a thunk-a thunk-a" sound rather than a whirring sound like a PTO mounted to the transmission would make?

Hello all,

I am new to the SS forum, I read a ton of the threads but this is my first post. I own an FMTV M1088 tractor and a M934A1 van truck so I am not a complete novice but am no expert by any means. My recent addition FMTV hydraulic pump will not stop trying to pump. I turn all the dials to the "straight up" position and you can still hear the pump actuating every so often. Is this normal?

I also drove the 1088 about 80 miles to our lake property and the transmission light came on and the transmission would only shift into 6th gear. I pulled the transmission dip stick and the oil is very clear so hard to tell but it looks to be overfull. I need to get it on more level ground and double check. It only happens when the transmission gets hot. Would the overfill cause the transmission to do this?

Thank you for any help or suggestions.

Pretty sure he’s talking about the air/hydraulic pump. The lower left button on your outside control box actuates it. Most likely a bad O-ring in there. Easy to pull out and check

 

[eugenehanway]

You need to read out the fault codes in the transmission. Press up and down arrows at tge same time. There are 5 memory positions D1-D5. It will flash D1 ?? ??(2 sets of numbers). Write the numbers down. Note if the mode light is lit. Press the mode button to step thru the 5 memory locations. Press both arrows again or shut off power to exit.

the PTO shouldn't be on unless you turned it on, are tou sure that is what is engaging? Any other sounds with it, like air being released?

Thank you for the information on how to pull the codes. I will take a look at it when I get back up there probably in 2 weeks and post what the codes are. Is there anywhere in the TM's that provide the information on the codes?

 

[eugenehanway]

.
This is a M1088. Unless you added a winch to the truck (most don't have one) is it possible that you are hearing the hydraulics that lower the spare tire and raise the cab? A kind of "thunk-a thunk-a thunk-a" sound rather than a whirring sound like a PTO mounted to the transmission would make?

No winch on the vehicle and that is exactly what I am hearing. I am sure it is for the cab, spare tire raise/lower pump. Once I release all the air in the system the noise stops.

 

[eugenehanway]

Pretty sure he’s talking about the air/hydraulic pump. The lower left button on your outside control box actuates it. Most likely a bad O-ring in there. Easy to pull out and check

Would the seal be in the box that you push the button on to raiser/lower the cab/spare tire? Or in the hydraulic pump itself?

 

[Ronmar]

Thank you for the information on how to pull the codes. I will take a look at it when I get back up there probably in 2 weeks and post what the codes are. Is there anywhere in the TM's that provide the information on the codes?

Yes the codes are in the manuals, but a better resource is the allison MD3060/3070 troubleshooting guide. Google TS2470EN and you will find places to download it like this https://www.manualslib.com/manual/1354071/Allison-Md-3060.html

 

[Ronmar]

Would the seal be in the box that you push the button on to raiser/lower the cab/spare tire? Or in the hydraulic pump itself?

Well that sounds like a couple of things have failed, or else a hack job is in play here. Plumbed properly there is a air operated control valve on the inboard end of the primary and secondary air tanks that feeds the air to the AOP control pushbutton valve at the hydraulic control panel. When you release the park brakes(apply park air) it also applies air to this control valve, shutting it off and disabling the AOP while driving…

 

[Mullaney]

Thank you for the information on how to pull the codes. I will take a look at it when I get back up there probably in 2 weeks and post what the codes are. Is there anywhere in the TM's that provide the information on the codes?

.
The Allison Troubleshooting Manual that @Ronmar linked is great to have. Attached below is a list of fault codes (quick and dirty). The manual gives a LOT more detail...

 

[eugenehanway]

Well that sounds like a couple of things have failed, or else a hack job is in play here. Plumbed properly there is a air operated control valve on the inboard end of the primary and secondary air tanks that feeds the air to the AOP control pushbutton valve at the hydraulic control panel. When you release the park brakes(apply park air) it also applies air to this control valve, shutting it off and disabling the AOP while driving…

So I can confirm that when the park brake is applied the pump continues to actuate, so it sounds like that control valve may be malfunctioning. Thank you for all the help this will help me cut down on the amount of time spent looking for the issues and more time fixing them. Which will lead to more play time. I really appreciate the guidance and suggestions.