Allison Transmission Tech Advice

Hello Allisonman

I have just bought but haven't taken delivery of a 1998 Holiday Rambler fitted with a Cummings and Allison 6 speed it's done 61,000 miles.
They don't have any service history for the coach but it looks well cared for, the question is what needs to be done to the trans at the moment to extend it's life or
make it trouble free, I intent to tour the US for 12 months and obviously put some serious miles on the clock, I'll also be towing a toad

Regards Loddy

The CUMMINS and Allison combonation is as bullet proof as it gets, but changing the trans fluid over to a synthetic ,(if it hasn't been done allready) would be my next move.>>>Dan

allisonman said:

  in 2010 Allison introduced a lot of software changes in the programming.  in your case it may be the "tailored shift speeds" feature is not set right in your program.  Allison's SIL bulletin 27-WT-09 says that this feature allows a user (programmer) to modify the acceleration based pattern, kickdown and, hold override shift speeds (downshifting with the arrow buttons on shift selector).  this sounds like some of the symptoms your describing.  these newer Allison's should shift like a Cadillac, super smooth to where you can hardly notice shifts and shouldn't hang up like your describing.  I would take the coach into an Allison dealer and have them check the calibration with Allison D.O.C.    they can also give the Allison tech. assistance center a call to verify the calibration.

            when they did the service on your trans did they reset the filter life monitor?  if the prognostics feature is enabled then after fluid or filter changes the filter life and/or oil life need reset or a wrench icon will start coming on in the shifter display and sometimes the dash display center.     

Click to expand...

Thanks for the insight. Should most Freightliner shops be able to handle that?

allisonman said:

        from what your describing it sounds like the trans is slipping but to be sure your going to have to bite the bullet and take the truck in and have someone look at it.  the speed sensor readings are very critical to the trans computer and if the wires to the turbine and output speed sensors especially are rubbed through then it can throw these readings off and fool the trans computer into thinking that the clutches are slipping.  the computer then in turn puts the trans into limp mode when it sees that.  did you look at the wiring harness near the passenger side inner fender-well?  its a common problem area.    I wouldn't haul any more loads of dirt with the truck until this problem is solved in case there is clutches slipping.

Click to expand...

I took it in to a tranny shop and they think it needs a computer. Let me add some other info i forgot to mention....

This all started when the ground strap from the motor to the frame failed and the truck would not start. So after diagnosing and finding this we put a new ground wire on.

Then the day after the transmission issue happened.

Then when looking over the transmission wires we noticed the ground on one of the two batterys was melted. (the screw in the battery post was literally melted and the wire was just hanging there) this was not the "main battery" but they are wired together. I replaced it with a new battery.

Also we took a wire plug off the side of the tranny (round & gray, Big) it was full of tranny fluid.

Not sure if this is coincidence or not but Maybe these will help you a little more?

I have just bought but haven't taken delivery of a 1998 Holiday Rambler fitted with a Cummings and Allison 6 speed it's done 61,000 miles.
They don't have any service history for the coach but it looks well cared for, the question is what needs to be done to the trans at the moment to extend it's life or
make it trouble free, I intent to tour the US for 12 months and obviously put some serious miles on the clock, I'll also be towing a toad

Regards Loddy

Click to expand...

    I'd change the fluid and filters in it give it an inspection for leaks and check to see if it had any codes by using the shifter.  this eng/trans combo is a pretty bulletproof set-up.  the filters(if they are Allison) will have a date stamped on them so you can see when they were last changed.  I did a fluid/filter change not too long ago on a 1994 motorhome with the same trans you have and the filters were original Allison 1994 dated!  I would use Transynd synthetic trans fluid. its available from Allison dealers in 1 gallon and 5 gallon containers.  the 5 gallon container is around 150 bucks.  its expensive, but very good fluid.        enjoy your trip 

Thanks for the insight. Should most Freightliner shops be able to handle that?

Click to expand...

        they may be able to.  they may look at you like your from mars if there is no codes in the TCM which I'll bet money there isn't.  Freightliner has to work on the entire chassis and isn't really specialized in one area. the Freightliner shop close to me is pretty good at fixing Allison's but they don't have reprogramming capability so they send that type of work to me. so they may refer you to another shop like stewart and stevenson ,  inland Detroit diesel and Allison , new England Detroit diesel and Allison, Pacific Detroit diesel and Allison, or a Williams Detroit diesel and Allison.  these shops are distributors for Allison and may be a better bet on solving this.

I took it in to a tranny shop and they think it needs a computer. Let me add some other info i forgot to mention....

This all started when the ground strap from the motor to the frame failed and the truck would not start. So after diagnosing and finding this we put a new ground wire on.

Then the day after the transmission issue happened.

Then when looking over the transmission wires we noticed the ground on one of the two batterys was melted. (the screw in the battery post was literally melted and the wire was just hanging there) this was not the "main battery" but they are wired together. I replaced it with a new battery.

Also we took a wire plug off the side of the tranny (round & gray, Big) it was full of tranny fluid.

Not sure if this is coincidence or not but Maybe these will help you a little more?

Click to expand...

  by the sounds of it you have a lot of issues with the truck that I wouldn't be able to begin to help you with over the internet.  it may need a computer, its possible that it could have been damaged due to the wiring problems but, these computers won't typically fail in the way your describing though.  they will usually just go dead and the trans would be in limp mode all the time.  your year of computer is pretty tough and I haven't seen very many fail.      the gray plug on the rear of the trans being full of trans fluid is pretty common with age.  it won't cause any codes.

Thank You for your time i really appreciate the help.

Good insight, thanks.

Thanks Allisonman

When changing from ordinary oil to synthetic is it a case of just draining what you can and then refilling with synthetic, they mix OK do they ?, or is there a
way of draining the oil from the torque converter

Loddy

When changing from ordinary oil to synthetic is it a case of just draining what you can and then refilling with synthetic, they mix OK do they ?, or is there a
way of draining the oil from the torque converter

Loddy

Click to expand...

yup, you just drain what will come out of the sump.  the torque converters do not have a drain plug like some other transmissions do.  the synthetic fluid will mix but after changing to synthetic you have to follow the non-synthetic fluid/filter change interval one more time (15,000 for filters and 50,000 for fluid).  after the 2nd fluid/filter change with transynd,  you can follow the synthetic drain interval (25,000 for filters and 100,000 on the oil).  make sure you use Allison filters,  some of the other filter manufacturers claim they filter smaller microns of particles (and they probably do).  this means they will clog faster and need changed more.  you don't save any money because your changing a cheaper filter more often than the proper one  ;D

Thanks for that very good advise

Loddy 

Hey Allisonman, New question for you. I just checked my trans fluid tonight while the rig is parked and leveled on jacks. It hasn't been started in about 3 days.  The fluid on the dip stick is WAY high, up past the cold and hot check marks.  Is this normal to read this high due to being shut down for so long?  I am concerned about an overfill condition. 

Thanks!

Sarge,, the drill is to check it with the engine RUNNING in nuetral.>>>Dan

Allisonman:

In an earlier response, you said you camp at Lake Superior.  Where do you live?  My son lives in Duluth and uf I need work done you're the man I want to see.

I'm kind of surprised it is above the cold mark, but would not be worried until I checked it hot and engine running, per the manual.  Besides, your Allison3000MH  has a built in fluid level check, which you activate using the buttons on the shift pad.  It shows Hi or Lo on the shifter display. Your Allison owner manual should describe how to do it. That's the best way to check the level, since the dip sticks aren't always calibrated right.  The dipstick is added by the chassis builder after fabricating the access tube for it, and sometimes they don't get it just right. That's why Allison builds in their own electronic level check.

I have checked my MD3060 many times with the engine dead and cold,,it allways reads well over full at the full/hot mark.  With the engine warmed and running it will be right on,  hence my suggestion.>>>Dan   (And my panel matches the stick)

utahclaimjumper said:

Sarge,, the drill is to check it with the engine RUNNING in nuetral.>>>Dan

Click to expand...

Yup, I know.

Gary, unfortunately I don't have the 3000 transmission.  I have a 2500 series that doesn't include the remote fluid level check, Or the transmission retarder... :-((

The concern is that the fluid levels are WAY over the hash marks on the dip stick. 

Hey Allisonman, New question for you. I just checked my trans fluid tonight while the rig is parked and leveled on jacks. It hasn't been started in about 3 days.  The fluid on the dip stick is WAY high, up past the cold and hot check marks.  Is this normal to read this high due to being shut down for so long?  I am concerned about an overfill condition. 

Thanks!

Click to expand...

      this may be that the fluid is stuck to the walls of the tube from not running in awhile and it needs to drain down.  there should be a tiny vent hole up by the dipstick handle(only in 1000/2000 series trans.!!) in the tube.  yours should be new enough to have it.  the portion of tube inside the trans needs to be vented also.  if they didn't vent the tube and it is the long fill type then the tube goes quite a bit into the trans fluid in the pan and it might take awhile for the fluid in the tube to go down.  try pulling the dipstick out so the seal is just out of the tube and rev the engine up to about 1500 rpm for about 30 seconds. let it go back to idle and then check it.  keep checking it for about 5 minutes idling.      when I do fluid changes it usually takes about a half an hour to fill and check the oil to get the level right because the dipstick tubes are so long and it takes a long time for the fluid to drain back into the trans.    the stick may also be calibrated wrong.  usually on the 1000/2000 series trans. if the trans is overfull it will spew trans fluid out the vent at the rear of the trans on top of the main case and it makes quite a mess.  the 3000/4000 series transmissions have to be gallons overfull before they will spew oil out the vent. 

Thanks, I will investigate.