OT: Allison powershift transmisson won't move when cold

Hi, Misterskill.
I have operated a couple of LD3s and an LD7 in the past and none of them showed the behavior that you are describing. Good, solid machines, although a little 'unsteady' on their feet due to the oddball center swivel design. The only time I got near an LD5, I had to stand it back on its feet with the Cat 941B that I was operating at the time. NO injuries to the machine but the operator's confidence took a beating.

The only thing that I can think of that you haven't mentioned is if there is a pressure relief valve in there somewhere that either has a weak spring or is sticking - or both. This might help to explain the fluctuations in the pressure gauge too.

Hope yer git it sorted.

Just my 0.02.

Hi, Misterskill.
I have operated a couple of LD3s and an LD7 in the past and none of them showed the behavior that you are describing. Good, solid machines, although a little 'unsteady' on their feet due to the oddball center swivel design. The only time I got near an LD5, I had to stand it back on its feet with the Cat 941B that I was operating at the time. NO injuries to the machine but the operator's confidence took a beating.

The only thing that I can think of that you haven't mentioned is if there is a pressure relief valve in there somewhere that either has a weak spring or is sticking - or both. This might help to explain the fluctuations in the pressure gauge too.

Hope yer git it sorted.

Just my 0.02.

Anyway got impatient and pulled the control valve assembly off. One the of the valves had a few marks on it and needed a bit of a tap to come out. I couldn't feel anything inside so i cleaned it up with some fine sandpaper and put it back.

Cleaned the whole thing up, put it back on. Started it up, put in 1 and off we go. Sucess!

Put it back in N, back in 1 and nothing. Took the assembly off again, nothing stuck. Removed the brake/transmission kickout and the same thing.

Remembered i would have dropped a bit of oil when playing with the filter ect. So i put 2 litres in it until it came out the top plug as i was instructed by the previous owner.

Figured i've got the service book now so i may as well read it. Started the thing up, gave it a few rpm and checked it properly by the bottom plug. 6 litres later it still isn't at the bottom plug and i'm out of oil so have to wait until tommorow.

Put it in first and off it goes, N and we stop, 1st and off we go again!

So unless i've accidently knocked somthing else and fixed it, looks like it was a stuck Main pressure regulator valve and it's been low on oil for the past 30 years!

Lesson learnt. Always check the service manual and don't trust the previous owner on preventive maintenance, no matter who it is!

Thanks for the help fellas

Ha too funny - RTFM! I'm glad you got it sorted out, nothing like a machine that does everything it's supposed to, even if the paint is not fresh.

that's a good story Mister! the kind of fixes i like and stories with a happy ending. I was thinking maybe a weak or broken spring etc...but great!

Hi Daniel,
WELL DONE, --cold oil gets trapped on the compartment walls/surfaces and so is slow to run back to the reservoir for re-use. Thus the pump is starving for oil and so is pumping air until it can warm up and flow back quick enough for the pump to recycle air free.
Low oil level is the result and as you say incorrect oil level checking advice could and did cause your issues.
Is there an oil volume amount to be added after an oil change given in the book that may work closer than a level plug which seems odd for an Allison trans.
Adding a liter or so of trans. oil until the unit works cold without sucking air could be one way to go--then watch for sign of overheating due to oil drag when hot--could be issues with the trans pump pickup tube being mis-positioned or such if this occurs.
Keep at it and smiling.
Cheers,
Eddie B.

[quote="edb" post=228279"]Hi Daniel,
WELL DONE, --cold oil gets trapped on the compartment walls/surfaces and so is slow to run back to the reservoir for re-use. Thus the pump is starving for oil and so is pumping air until it can warm up and flow back quick enough for the pump to recycle air free.
Low oil level is the result and as you say incorrect oil level checking advice could and did cause your issues.
Is there an oil volume amount to be added after an oil change given in the book that may work closer than a level plug which seems odd for an Allison trans.
Adding a liter or so of trans. oil until the unit works cold without sucking air could be one way to go--then watch for sign of overheating due to oil drag when hot--could be issues with the trans pump pickup tube being mis-positioned or such if this occurs.
Keep at it and smiling.
Cheers,
Eddie B.


 [/quote]
about 8.5 gallons in total according to the book. So the instruction is to add 6.5 after a service (7.5 after a rebuild) and do the level plug process.


Actaully kind of glad it didn't starve completly and loose drive going up a hill or somthing

Hi Daniel,
you can do the fill by volume test by simply draining your oil into a clean container--measure the volume and refill as for a simple service and then do the level plug thing after a short run and say 3-5 minutes wait time before checking the level. at the plug again.
Other methods may work as well.
Cheers,
Eddie B.