m35a3 wont go forward

[Rustygears]

Start with the easy items: fluid check at operating temp, engine running per TM. What are you using for fluid? Motor oil (mil method) or Allison spec'd ATF? Have you looked at the oil on the dipstick? Is it discolored? Does it smell burnt or rancid?

These items will help diagnose a fluid based issue and/or a fried set of clutches in the tranny.

The vent is a hose leading from the top of the tranny up behind the cab to a cluster of 3 vents for various things. Sounds like you haven't read the TMs. That is your first issue. The vent is clearly shown in the TM. The puddle of oil if coming from the dipstick/fill tube may be vent related. It also may be a leaking tranny cooling line that attaches in the same area as the vent. Unless you recently filled the tranny, I would doubt it to be a overflow due to plugged vent.

It seems there may actually be more to the story than has been indicated.

 

[Warthog]

Anybody have a clue ?

Three pages of responses. I guess none of them apply.

Bigboy toys sometimes require bigboy repairs. Take it to an Allison repair shop.

 

[hardhead]

WE had a Allison equipped all wheel drive bucket truck with the EXACT same issues
It was towed to a Allison dealer in Bedford for repair
It was diagnosed as a sensor (I don't remember which one)
If I get back to the staging area this week I will review the maint. records and find out
JB

 

[Coalman]

Thanks Hardhead I didn't think there where any senors on that, isn't it all mechanical? Boy I hope you are right. Well I just got done dropping the pan and cleaning the screen. I changed the external filter and put in 2 1/2 gallons universal transmission fluid. Still the same. I figured it wouldn't help but it was worth a shot . The oil I drained out did smell somewhat burnt. I also checked the detentes on the shifter and they are all fine next step I guess is have somebody take a look at it .

 

[quickfarms]

take it to the doctor, Allison.

 

[hardhead]

The bucket truck is a 1995 (a relic for electrical construction) that is about the same frequency as the A3s to further explain the symptoms you rug the throttle,the motor would rev up about half speed( turbo spooled up and whistleing) and just sit there groaning, there was fluid dripping off the output shaft on the tranny( mimicing a rear seal) we thought it was toast called for a hook.
I wish I knew more about the A3s If my fleet manager would call me back I would get an answer (he is pretty sharp on Alisons) and let you know what he thinks GOOD LUCK JB

 

[quickfarms]

Do you remember how many gears the trans in the bucket truck had?

 

[Coalman]

Thanks Hardhead any help is great

 

[hardhead]

It is a 5 speed forward 1 reverse , 2 speed transfer case on a freightliner chassis powered by a 5.9 Cummings, It has a computer

 

[quickfarms]

The trans is available with either nuetral or nuetral and park.

Attached are the allison operators and mechanic tips manuals that are available on the allison website.

I se that you have created two other posts, one looking for a trans and one looking for a rebuild kit.

I have never seen a rebuild kit for these trans, I do not know if allison sells the kits or makes you go through there rebulders.

This is not a complex trans and the rebuild would cost about what my wifes car cost. The electronic trans are a whole other issue.

 

[hardhead]

Thanks for going to the trouble to post the PDFs quickfarms I am in for some" light " reading maybe I will learn something....

 

[glcaines]

Thanks Hardhead I didn't think there where any senors on that, isn't it all mechanical? Boy I hope you are right. Well I just got done dropping the pan and cleaning the screen. I changed the external filter and put in 2 1/2 gallons universal transmission fluid. Still the same. I figured it wouldn't help but it was worth a shot . The oil I drained out did smell somewhat burnt. I also checked the detentes on the shifter and they are all fine next step I guess is have somebody take a look at it .

Be very careful what fluid you put in. The Allison 1545 is designed to be used with Dexron III and the newer TranSynd. Dexron VI for instance will destroy the seals. The motor oil is not compatible with Dexron III, TranSynd or any of the other fluids. Since you were unable to use the drain and fill method, you still have a lot of motor oil in your transmission and TC. You need to take it to an Allison service center, talk to an Allison tech, or ask questions on an Allison forum. You also need to go through and read as many posts as you can on the A3 truck, many of which involve the Allison transmission.

 

[trukhead]

The trans is available with either nuetral or nuetral and park.

Attached are the allison operators and mechanic tips manuals that are available on the allison website.

I se that you have created two other posts, one looking for a trans and one looking for a rebuild kit.

I have never seen a rebuild kit for these trans, I do not know if allison sells the kits or makes you go through there rebulders.

This is not a complex trans and the rebuild would cost about what my wifes car cost. The electronic trans are a whole other issue.

Thanks for posting the manuals.

 

[BackWoodsDrifter]

Just a quick question for the op, when did you get your deuce, are there numbers from the original unit and/or is the paint scoffed on the back of the bumperets?
had that problem with a duece we were turning in with our unit probably round mid june-july of 2011. had reverse in all the gears ended up having to push it 400 yrds to a parking lot with another deuce so it was out of traffic. Didn't think to get the numbers off of it to post on here, but we turned them into Chambersburg, from there who knows where they get sent to.