M923A2 Transmission Question

[kdaniels]

I picked up a nice M923A2 from RedStone this week but have found it seems to have a slight transmission issue. After a few minutes of operation the truck is VERY slow to come off the line in 1-5 but once it starts moving it seems to gather speed fairly quickly and shifts normal.

On the drive back (250 miles) i found that it ran and shifted fine uphill and down and would run down the road easily @ 50-60 mph. It was only when i had to stop at a red light that the tranmission seem to want to stall the engine and problem was worse if truck was facing up hill which did cause the engine to stall and the butt to pucker. ( hand throttle and neutral @ next light) Transmission temp ran normal 170-190 degrees.


The truck was released from the air force and all the paper work from the maintenance group was in a folder i found in the vehicle listing problems (all very minor) with the vehicle and this problem was NOT noted.

The only fliud issue i have found is the transmission is WAY over filled. So my question is could this be the root of my problem or is it something worse?


I might add that this issue does not appear when using reverse..throttle reponse is instant.
So any thoughts on the problem would be very helpful.


THANKS !!!!




SEMPER FI !



keith

 

[1 Patriot-of-many]

What speed is your engine idling at? Mines very slow coming off the line too. I assumed that was normal

 

[kdaniels]

Engine idles about 600-700 rpm.....and it is ALOT slower off the line than my M923 that was fresh out of referb in 2010. Test driving it some today around home , away from the stress of this 20k elephant dying on a major highway, i have noticed it's not as bad as it was on the day i picked it up. The engine doesn't stall now when you come to a stop but it still is slow off the line and the pedal "seems" stiff, or it could be i'm pressing so hard trying to get it rolling that it just feels that way. But there is still something not right with the acceleration from a dead stop.

I think i will try changing the filters and fluid and see if that helps. I see the air force is running dextron in it so i will go back with that. Other than that issue with the allison the vehicle is in great working condition. Maybe i'll find the solution soon, i did a search in the forum and it seems this issue hasn't been addressed before or if it was not were i could find it.



SEMPER FI !


keith

 

[kdaniels]

Quick update on my transmission issue......it seems to be getting better. At this point all i have done to it , until my pan filter kit shows up, is to drive it around the back roads with alot of starting and stopping to really work the gears thru their range. It's not as quick off the line as my M923 but it is 100% better than it was on the day i picked it up from RedStone.

Only thing i can figure is these A2's are not very fast on take off and some of them don't like to sit for long periods without being used.



SEMPER FI !!


keith

 

[Rifleman]

First thing i would do, if in deed the trans oil is over filled as you stated in your post would be to get the oil level right. I would drain off the extra oil and then take it for a test drive and check for the problem. Remember To much oil in your transmission can be as bad as to little oil, so this might be a easy fix.

 

[kdaniels]

Thank ya there Rifleman....i did get that level dropped down by draining alittle out....but the problem is still present. Part that doesn't make any sense to me is the TM says transmission will over heat if over filled....and this one ran normal (170-190) all the way home. Next conversation will be with the Allison mech's in Albany Ga...they were recommended as the "source" in my area. I will post up as i narrow down this issue.


SEMPER FI !!



keith

 

[kdaniels]

UPDATE on my allison issue.....I put my truck under load with a chain pulling up a small cluster of oaks (in reverse). I ended up breaking the harbor freight chain and decided to call it a day and park my truck. Truck sat for a few days when i went out and started and let it idle for a half hour or so. Hopped in to take it down the road, placed it in gear....depressed the gas pedal rather hard and the rpm's went up but NO movement, got off the pedal to let the rpm's fall and tried again.

This time after about a second or two of throttle there was a "thump" that sounded like it came from down and behind the cab and off i went. Now the truck has no issue with the slow throttle response i had before. Vehicle preforms like i think it should from a dead stop where before it was a pain to get it to move from a dead stop.

Transmission still shifts out fine and have zero leaks and braking is good as before. I am puzzled at the "thump" as it had never done that before but noticed a world of differnce after. Any thoughts ???

I have read almost every thread on the problems folks are having with the allison and checked and rechecked all the usual suspected problems/fixes. This doesn't fall into any of those solutions but it seemed to have worked for me. I dont worry about pulling out into traffic any more and i now enjoy driving it more than my M923.


SEMPER FI !


keith

 

[seano11]

Did the the Rpms go up freely or did it feel like the truck was under load ?

 

[Suprman]

Turn up the fuel it will take off nicely.

 

[RustyM923]

Turn up the fuel it will take off nicely.

Is this under the access cover on the top of the pump?

 

[Suprman]

It's a 3/8 hex plug I believe. There will be a flathead screw with a set nut I believe the nut is 9mm. Use a 1/4 deep socket to loosen the set nut just a bit. Leave the socket on use a small flathead thru the socket turn the screw 3 turns counter clockwise then set the nut back down snug. Run the fuel control back and forth make sure it still moves freely then put the plug back in.

 

[kdaniels]

The truck felt like it was tied down.....i could tell it was straining to break free of "something". On the second attempt was when i heard and felt that "thump"....and off she went.




SEMPER FI !!


keith

 

[Coffey1]

Stuck brake? /park

 

[kdaniels]

I lazer checked the drums/hubs for heat on the drive home back in May (300+ miles) and didn't find anything hot... Not saying it couldn't have been stuck alittle, Who knows what freezes up on these vehicles once they sit up for awhile. But the truck ran too good and shifted up and down well for it to be something serious.

Have been driving it 8-10 miles every week around the area just to put some wear on it and try and determine if it had any major issues before i got comfortable calling it "dependable". With this issue clearing itself up i feel better about the vehicle now.
With this out of the way i can move on to replacing the old super singles with newer tires. Oh joy !!


SEMPER FI !!


keith