Allison 654 Issues

[skytrends]

Just got back home from a 23 state, 8000 mile trip. Trans has acted a little strange since I've owned the bus and previous owner said it's always been that way . Anyway, When cold it seems to work fine However, once warmed up and after coming to a stop like at a traffic light it, seems to be in neutral and not dropping back to 1st. for about 5 to 10 seconds. Hasn't really been much problem but, yesterday as I was getting close to home it kept upshifting and down shifting rapidly like it couldn't find the right gear fairly level road at 45 to 50 mph. Then when I got in my driveway and started to back it in it's place it seemed to shudder while backing. Checked fluid level and it was good. No foaming on dip stick light brown color, smell's used but. not really burnt, no pieces of clutch material on stick. Drove it this morning and all seemed fine till it got warm then same thing. Thinking fluid and filter change or maybe transmission modulator malfunction? Opinions please?

[luvrbus]

It is a low pressure problem,install a gauge on the test ports for the converter and clutch packs and read the pressure could be the converter if who ever did the setup used a standard converter behind the 6v92.Drop the pan first that is where the parts will be with damage not on the stick.That transmission is a little iffy behind a 6v92TA

[skytrends]

Thanks Clifford! The transmission has been in the bus since 2002 but I, had heard they were a little weak too. Not sure what other Allison would be a direct bolt in? Looking at a couple on Ebay now but will have to wait tell I, recover from the trip.

http://www.ebay.com/itm/M931A2-M923a2-M924-M925-M926-M936-m931-m934-5-Ton-Allison-MT654CR-Transmission-/331577363130?hash=item4d338d0aba&vxp=mtr


http://www.ebay.com/itm/M939-M939A2-Allison-MT654-Depot-Rebuilt-truck-transmission-2520-01-117-3010-/181732930334?hash=item2a5020731e&vxp=mtr

[dickegler]

I had one that acted in a similar manner.  Switched to 30 wt rotella, problem disappeared.

Dick

[luvrbus]

Yea 30w or 15/40 will buy you more time unless that is what you are running now.When you pull the pan to change the filter you will have a better understanding on what is going on   

[skytrends]

Ok, when I get a few runs in my truck under my belt I'll pull the pan and have a look. Maybe change to 30 wt. It is trans fluid now. Is there an adjustment I can make to turn pressure up a little?

[RickB]

I used 15/30 rotella about 60 k miles ago and have never had an issue again. It would shudder and howl when taking off on an incline before the switch. I highly recommend the switch to motor oil.

The reason I used multi-viscosity is I live in a cold climate and you can actually get to much pressure and break stuff with thick oil. I let my bus warm up for a few minutes longer since the change but it works awesome.

Rick

[luvrbus]

The easy way for you is check the governor pressure that will be at the rear of the transmission a 1/8 th plug run the engine at about 600 rpm in neutral @ normal operating temperature if you don't read 82-91 pounds find another transmission it may save you 10 gals of oil