Allison trans problem

[tommildren]

i have a 2000 dsdp with cummins isc 8.3L and the transmission is the allison
the trans started acting up yesterday. it wont downshift, it trys but it just buckes and jerks so i had to baby it to our destination in clermont florida by not letting it try to shift. good thing florida is almost flat. will get it to an allison repair shop in a few weeks but im curious if anyone else has had the same problem and what the fix was. trans has no leak, fluid full and runs normal temp at 180 to 190.

[racer0624]

I'm going to sound kind of dumb on this but I had this happen about 8-9 years ago on an SOB. My "remember" isn't as good as it once was. Where the throttle linkage is connected there was a "L" shaped bracket where the cable is adjusted that had cracked. I replaced it. As I remember initally it kept wanting to downshift requiring higher than normal RPM to get to the next gear. My next adjustment went to far the other way causing the need of manually downshifting. I finally got it right.
Hope this helps.

[clubmed98]

i had a shifting issue on mine and it was caused by less than 12 volts coming from the batteries..alternater had died..beleive it was slow up shifting and very harsh shift...probably not the same as your issue, but they do use electronics so might want to check and make sure you show 13-14 volts when running..

[tommildren]

Quote:

Originally Posted by clubmed98 i had a shifting issue on mine and it was caused by less than 12 volts coming from the batteries..alternater had died..beleive it was slow up shifting and very harsh shift...probably not the same as your issue, but they do use electronics so might want to check and make sure you show 13-14 volts when running..

I did have a battery issue just before this trip and replaced all 6 batteries, showing 13.2 volts now, 8 days and 1000 miles later but I didnt check it while driving. am plugged into shore power now.

["007"]

The 13.2 volts may be off your converter output. Unplug shore line and than take a reading. With new batteries they may need a full charge from a battery charger and transmission will be supplied 12v from chassis batteries not house batteries, If you changed chassis batteries they would require full charge from battery charger also.

[tommildren]

I thought I would post the solution as others may have a similar problem.
What wouldnt allow the transmission to down shift was not a trans problem at all. I took it to Florida Detroit Diesel- Allison in Orlando Florida where I met a great bunch of people. during the entire process the mechanic would come to the waiting room and let me know exactly what was happening. He said he was sure it was a fuel delivery problem and not the transmission. He eventually said it was contaminated fuel or just junk in the gas tank as the rig was in storage for months. He showed me the mess in the plastic bowl at the bottom of one of my fuel filters. It was not there when I left home as I looked. He changed both fuel filters and we took it for a test drive, ( he took off his shoes and placed a plastic bag over the seat he sat in) and the problem was fixed. Great people and the bill was about $250 for filters, checking and clearing a code, diagnostic and 2 test drives. Bill the mechanic, appoligized for the high cost of the filters because he couldnt get the oem ones that day, he gave me the number to order them direct from spartan which i have now done at about $19 each. I now carry my own spare filters