2005 Itasca, 350cat with Allison3000 trans problem

[webber46]

At the end of my 1200mile trip home my trans started acting up. By this, the cruse set to 63mph I started to lose speed on a slight grade to the point I had to take the control off and manually downshift the trans according to the speed I was at that time. 30mph-3rd gear, 40-4th gear and so on to 60-6th gear. All these came with a liberation with the accelerator being pressed. to keep increasing the speed. Once the 63mph was reached, set Speedo and go to the next slight grade and start all over. No check info lights appeared to start with but then would appear until the shifting procedure was complete and then would go out. Need HELP !!!! I did make it home and to storage. Thanks

 

[DonTom]

Need HELP !!!!

Sounds like a simple vacuum leak to me. Vacuum is what tells the auto tranny to shift.

When climbing up a hill, there is less vacuum available and then it becomes more critical. Most vacuum is at idle, when the TB is closed. Opposite when wide open to go up a hill.

Look for loose vacuum hose or a leaky hose.

-Don- Reno, NV

 

[webber46]

Sounds like a simple vacuum leak to me. Vacuum is what tells the auto tranny to shift.

When climbing up a hill, there is less vacuum available and then it becomes more critical. Most vacuum is at idle, when the TB is closed. Opposite when wide open to go up a hill.

Look for loose vacuum hose or a leaky hose.

-Don- Reno, NV

Thanks Don, Will do the diagnostics later today and see if it leads in the same direction. sure would be nice to just be the vacuum leak.

 

[John Canfield]

Did you check the fluid level? When was it last serviced? Does it have Allison synthetic oil? Circa 2004/5 transmissions left the factory with regular dino fluid. I forgot if the transmission on our previous Horizon came with TransSynd oil or not.

Here's a link to the troubleshooting manual.

 

[Gary RV_Wizard]

Sounds more like a lack of engine power than a tranny problem. The tranny was shifting to use whatever power was available. For starters, I'd change the fuel filters and maybe the air filter as well. Either one can starve a diesel if somewhat clogged.

I thought the WTEC III Allison 3000's were strictly electronic control rather than vacuum. And there is no TB to produce the vacuum in a diesel.

 

[webber46]

Thanks John, haven't looked at anything yet but I did change the filters and fluid before my trip. Thanks for the link, will have a copy to diagnose with the codes. I want to thank Gary for his Insite also. I changed the air filter and fuel filter at the time I worked on the trans. Will keep you updated as I proceed when the weather gets better. 6" of snow the day I got home wasn't a good thing for me but I'll live.

 

[Utclmjmpr]

The fuel filters would be the first look..>>>Dan Don must have missed that it is a CAT diesel, and very sensitive of dirty fuel filters. Always carry spares and know how to change them,, a loss of power is the first indication that it's time.)

 

[DonTom]

Don must have missed that it is a CAT diesel,

Yep. I was way off on that one. I was thinking gasoline when I posted that. And now I know the Allison tranny doesn't even use vacuum.

-Don- Reno, NV

 

[SCVJeff]

Yep. I was way off on that one. I was thinking gasoline when I posted that. And now I know the Allison tranny doesn't even use vacuum.

-Don- Reno, NV

We don’t even have enough vacuum to run the dash heater VAV’s. That requires an aux pump that has its host of issues too

Having said that I have a friend that runs Bio in a 36’ Journey/ CAT. He could tell he had a filter blockage coming up by his loss of power. No other alarms or indications. Thats sure what this sounds like..