m35a3 wont go forward

[Coalman]

I have a m35a3 and at it wont go forward I went to take it for a ride today and it didn't want to shift out of first or second so I put it in nuetral and back in drive and it was ok about a minute or two I went to back up and it did I then went to go forward and nothing I had to drive it home in reverse I checked the fluid level and it seemed ok I also checked the linkage and it seems to be ok does anybody have any ideas Thanks Kevin

 

[quickfarms]

Have you gone on the Allison websit and down loaded the manuals?

 

[roscoe]

I had that problem on a f350 and it was the transmission. Except it would go forward but not reverse. I don't remember what the plastic / electronic part was called, but I pulled it off and put another one on and it would go in reverse and not forward. Transmission had to be rebuilt.

 

[Hoefler]

Check you emergency brake linkage. When the grease gets cold, the spring return is not strong enough to pull it back. Going forward seems to drive the brake shoes into the drum on the E brake.
Loosen up your e brake handle knob and see if it helps.
If not-check your fluid level-it may be low.
Pete

 

[wsucougarx]

Found this:
http://www.steelsoldiers.com/engine-drivetrain/80638-m35a3-help.html

 

[Coalman]

It is not the e brake it coasts forward in neutral also I put it in low range still doesn't work One other thing it goes backwards in R N and D so it must be in the adjustment It doesn't seem to be in the cable or external linkage

 

[Coalman]

That post above for help is exactly what happened only thing is mine go backwards in R N and D so I am thinking it is in the adjustment I will check fuild again just to make sure

 

[Coalman]

One more thing I just went and looked under the truck there seems to be oil up on the back top of tranny And also the tranny never seems to shift in neutral it seems to be in either reverse or seems to lockup but not move Is there an overflow that the presure is pushing the oil out ?? Thanks I don't even know where to go next

 

[Hoefler]

Hmmm...possible that you have a plugged vent (back of cab), transmission got warm and forced fluid out of vent under pressure?
Have you checked your fluid level? When I flushed mine, I ended up a quart low-took for test spin and it did not want to shift. Filled it up and it returned to normal.

 

[quickfarms]

If you run out of ideas contact your local allison dealer/rebuilder.

 

[glcaines]

The leak is possibly from the vent on the transmission, but likely not causing your problem. Have you tried going to one of the Allison transmission forums? There are several active forums dedicated to Allison transmissions. The Allison 1545 transmission is a relatively common transmission. Google Allison transmission forums.

 

[Coalman]

I really had not been driving it much to get it hot Also I was just thinking how do I check the level when it never really goes into neutral Would that give me a false reading When I checked it without it running it was real high on the dipstick with it running and in the neutral slot it was between the lines It seemed like it was actually in gear thought so How do I get a true reading is there a vent some where plugged or could the screen be blocked in the pan I don't know if I should drop the pan or not I do now the first thing I am going to do is take the linkage of and see if the selector is working on the side of tranny Any and all help is greatly apprecited

 

[gimpyrobb]

Wow not one period comma or nothing There was some capitalization in there tough I had to read it 6 times before I could understand what was being said Good luck I'm sure it won't be cheap

 

[goodguyzy]

Probably posting from a phone.

 

[Bob H]

I know nothing about the Allison.
Your issue sounds familiar though
I had an issue with an old Chevy not shifting, the linkage between the selector on the outside of trans and the piston that it moved in the valve body had came undone.
I dropped the pan and it was visable.
Before you do that, look up a parts diagram.
Here's hoping that you find that the external linkage is loose

 

[green machine]

I know its probably not what u want to hear and I hope it isn't ur problem but I just went through the exact identical thing. It welded the fourth gear and reverse clutches together.went reverse in D ,N and R. When u put it in 1 thru 3 it didn't move just like the tranny was locked up. After dropping the valve body a couple times I finally took it out and found the real problem. Hope u get it figured out.

 

[Coalman]

Anybody have a clue ?

 

[gimpyrobb]

Probably posting from a phone.

Just sayin! Its lots easier to help when you don't have to read a post 6 times. When I post from my phone, I can install periods, commas, and other symbols. Maybe his phone is broke too.

 

[doghead]

• Do not post in all CAPS or in giant run-on sentences without punctuation. Do not post as if texting and do avoid the use of texting abbreviations. We are not the grammar police but we want everyone to easily read your post in at least 8th grade English. It is extra work to post proper sentences from a smartphone but the result will be greatly appreciated. Please do your best to use capitalization, proper spelling and punctuation. It makes it easier for everyone to read!

 

[unaffiliated]

I know you don't want to hear this but.....When Mercedes electronic transmissions crap out they will go forward/reverse in any gear, even neutral, or they just don't move at all. I know nothing about Allison automatics, but it sounds like a more serious problem than just fluid level or linkage, to me anyway. On a side note. I use Mozilla Firefox and it spell checks automatically while you type. It doesn't correct bad grammar or punctuation though.