Allison Tech for 40 years

[Det57]

I read this entire thread tonight and learned a lot.

Im going to climb under my 2000 Fleetwood Discovery tomorrow and see what Allison transmission I have. I am also going to check for any codes. Im interested in changing my trans oil and filter (s)? as the coach has 42 k and Im not sure when if ever it was done. Ill be checking back in real soon for some final advice. Thanks guys!

[LickingTexas]

Originally Posted by Allisonman

I have been strictly an Allison Tec, manager, Allison rep and now outside sales for 40 years. I used to answer questions before about 15 years ago but became quite busy in my job and lost track.
I have come here to try and lend my expertise to RV owners who have questions about their Allison Transmissions. I really enjoy helping out so please if you are having an issue with your Allison, please leave me a question. I try and check in every other day so please be patient. Thank you and "Have a great day!"

Hi Allisonman, hope you can help, if not, take care, and enjoy life.. I have a 1996 Allison md 3060, in a 96 holiday rambler, freightliner frame, 5.9 Cummins, my speedometer has quit, and the cruise finally quit working. I have the push button shift selector. The only code I get with the push button selector, is OL 70. The trans, seems to work great, no problems. I took out the out put sensor, and ohms checked it, I think it check ok. Do you have any ideal where I should start, or do? Thank you.. Randy

[callen]

My 2001 c c Intrigue has 65000 miles on it, 8.3 cummins and 3000mh trans. I would like to change trans. filters and oil. Need advice on what oil to use. thank you

[DanRussell]

Originally Posted by Allisonman

I have been strictly an Allison Tec, manager, Allison rep and now outside sales for 40 years. I used to answer questions before about 15 years ago but became quite busy in my job and lost track.
I have come here to try and lend my expertise to RV owners who have questions about their Allison Transmissions. I really enjoy helping out so please if you are having an issue with your Allison, please leave me a question. I try and check in every other day so please be patient. Thank you and "Have a great day!"

Allisonman: I have one a little bit afield, but I'm tired of getting wrong info. & played for stupid, so please help.
I have a 1998 GMC T7500, Cat 7.2, Allison AT545; When it's cold, it shifts up & down perfectly. When it reaches operating temp. it can drop into 3rd at highway speed just because it wants to; when pulling away from a stop, it upshifts half way, and no amount of manual shifting or throttle feathering makes any difference--- which means I'm trying to do road speed in a lower gear. My engine coolant temp gauge goes right to the red mark.
I thought maybe the modulator; a diesel shop here says it's a shift solenoid. The authorized shop says they will do a diagnosis for "only" $280, and I'll bet the diagnosis is a new trans..
One other thing: eBay has a multitude of used 545's; my regular mechanic --- he's not a tranny man --- says the 545 is not interchangeable, there is no swapping of bellhousings, so if I buy used it has to be from a Cat. ???

[dbarton291]

Originally Posted by DanRussell

Allisonman: I have one a little bit afield, but I'm tired of getting wrong info. & played for stupid, so please help.
I have a 1998 GMC T7500, Cat 7.2, Allison AT545; When it's cold, it shifts up & down perfectly. When it reaches operating temp. it can drop into 3rd at highway speed just because it wants to; when pulling away from a stop, it upshifts half way, and no amount of manual shifting or throttle feathering makes any difference--- which means I'm trying to do road speed in a lower gear. My engine coolant temp gauge goes right to the red mark.
I thought maybe the modulator; a diesel shop here says it's a shift solenoid. The authorized shop says they will do a diagnosis for "only" $280, and I'll bet the diagnosis is a new trans..
One other thing: eBay has a multitude of used 545's; my regular mechanic --- he's not a tranny man --- says the 545 is not interchangeable, there is no swapping of bellhousings, so if I buy used it has to be from a Cat. ???

Okay. 1. The AT545 has no shift solenoids. 2. The AT545 has a #3 SAE housing. It will bolt to any engine with that housing or a suitable adapter. The difference from transmission to transmission in those is the valve body calibration and torque converter. There is an assembly number in the nameplate which tells you which one you have. 3. Sounds like governor pressure is leaking off when it’s hot. It’s not the modulator. How many miles are on this unit? Is it the vehicle’s original transmission or has it been replaced sometime in the past? For a clue take a look at the name tag and see what it says. Many rebuilders replace the original name tag with one of their own.

[DanRussell]

How do I get around the torque converter issue? Is the converter-to-flywheel bolt pattern also SAE, so I buy a used unit that has a converter and I'm good to go, or is an adapter needed? What's involved in fixing governor pressure leaking/how do I test for it?
I truly appreciate your help. Thank you.

[dbarton291]

Originally Posted by DanRussell

How do I get around the torque converter issue? Is the converter-to-flywheel bolt pattern also SAE, so I buy a used unit that has a converter and I'm good to go, or is an adapter needed? What's involved in fixing governor pressure leaking/how do I test for it?
I truly appreciate your help. Thank you.

There is no torque converter issue. The converter bolts to a flex plate.
You won’t be able, on your own, to measure governor pressure or fix it. My advice to you is to read the tag and answer my previous questions. With that information I may be able to help you decipher how to find a replacement transmission. You can also go to www.allisontransmission.com and find an authorized shop near you. That way you won’t be talking to folks that think there are shift solenoids in an AT545.

[DanRussell]

AT545RM
Part # 29508650
Serial # 9108231225
Reference # 08-037

[Steve Kieffer]

Need advice: engine or transmission problems?


I just completed a drive from Florida to eastern Wisconsin. We cancelled our planned multiple week trip from there to the Upper Peninsula of Michigan, Minnesota, North Dakota, Montana, Idaho, Wyoming, Colorado and return to Florida in significant part because of the unacceptable behavior of this engine. The observations below briefly explain the great difficulties I experienced driving this motor home.

1. During moderate to fast acceleration the engine rpms increase to 2,000, the governor audibly takes control, then after a delay the transmission shifts up one gear.
2. During no load down hill acceleration the engine rpms continued to increase beyond 2,000 and the transmission shifted at 2,100 without the governor controlling the engine.
3. During normal driving with the engine brake off the transmission appears to perform properly.
4. With the engine brake on at highway speeds of 70 – 75, when the accelerator is released the following happens:
a. Engine brake light goes on
b. Transmission down shifts two gears
c. Engine rpms rise to 2,300
d. Engine brake does not engage until rpms drop to 2,000
e. At 1,900 rpms the transmission down shift another gear, rpms rise to 2,300 and the same cycle repeats
f. During most of this time the engine brake is not working.
5. At slower speeds the same problem occurs, for example, on an Interstate highway ramp transitioning from one interstate to the next I was driving at 40 mph. The driver in front of me slowed excessively. I backed off on the accelerator, the engine brake engaged, rpms rose to 2300. I was unable to increase speed until the rpms dropped below 2,000.
6. Anytime the engine rpms are above 2,000 and the engine brake is on the coach will not respond to accelerator input and turn off the engine brake, or shift the transmission up a gear. Turning off the engine brake switch has no impact. Trying to manual shift the transmission has no impact. In the example that began at 75 mph, the coach continues to slowly reduce speed until 2,000 rpms was reached, which is approximately 60 mph in 4th gear and took almost 14 seconds.
7. I had an experience while driving in the left lane at 75 mph, I needed to slow to 70 mph and merge to the right lane behind a semi. I was unable to do that. The coach continued to slow to 60 mph, causing traffic problems behind me, and the opportunity to merge right disappeared as traffic closed up.
8. Some times it is possible to very carefully feather the accelerator, while watching engine rpms, and avoid down shifting two gears, thus maintaining rpms at 1,900 where the engine brake will work. In those instances there is no apparent performance difference between low, medium or high engine brake settings. This is a very difficult task, impossible to consistently perform or maintain over any extended period of time.
9. And, here is one general example. Due to the unusual behavior of this engine, the trip from Athens, AL to Dothan, AL, which is less than 300 miles, took 9 hours. There was one fuel stop and two 10-minute breaks. Driving the north Alabama hills, and Birmingham and Montgomery traffic was very difficult. Frequently I was suddenly slowing traffic behind me down by 10 – 15 mph when the engine brake engaged. I’ve driven this route many times in a coach with the ISX15 engine and it should have been done in 5 hours, including two 10-minute stop
10. I am concerned about potential engine damage being caused by the repeated over-revving of the engine.

Over the past 11 years I have owned a driven three motor homes with the ISX15 engine all over the country including many trips to the Rockies, numerous high mountain passes, I80 to California, etc. with long descending grades as step as 8 – 10%. The ISX15 performs admirably. It is easy to use the engine brake in all conditions and manage the vehicle’s speed.

The current performance of the ISX12 engine is a dismal failure compared to the ISX15. Driving in traffic with the engine brake on is hazardous. Plus, it is impossible to manage vehicle speed on downhill runs using the engine brake. As it currently performs I would never consider driving this coach in mountainous regions. That is a major problem for us. One of our biggest uses of a motor home is to tour the western states.

[dbarton291]

Originally Posted by DanRussell

AT545RM
Part # 29508650
Serial # 9108231225
Reference # 08-037

That is actually an Allison ReTran remanufactured transmission. It is 2600 RPM valve body calibration with a TC290 torque converter. It has a PTO gear in it and a 16 tooth speedometer tone wheel.
That's a pretty common configuration.

[DanRussell]

Based on your previous comment about the governor pressure leaking off, when I take this in to the dealer, what can I expect them to do? What's involved in the fix? More importantly, if it is the governor, ballpark, what should it cost to repair at a shop rate of $140? I can get a guaranteed used unit from eBay for $300 plus freight plus R & R.
Thanks for your time.

[dbarton291]

Originally Posted by DanRussell

Based on your previous comment about the governor pressure leaking off, when I take this in to the dealer, what can I expect them to do? What's involved in the fix? More importantly, if it is the governor, ballpark, what should it cost to repair at a shop rate of $140? I can get a guaranteed used unit from eBay for $300 plus freight plus R & R.
Thanks for your time.

The problem with governor pressure leaking off is sometimes the governor bore in the main case is worn and you're money ahead just to get a rebuilt transmission with a guarantee.
A $300 AT545 would be a good thing if you get lucky and get one that was working well when removed. If you're using this truck, I'd get a reman from a local Allison shop and cut to the chase to get the vehicle back in service. Just my opinion.

[dbarton291]

Originally Posted by Steve Kieffer

Need advice: engine or transmission problems?


I just completed a drive from Florida to eastern Wisconsin. We cancelled our planned multiple week trip from there to the Upper Peninsula of Michigan, Minnesota, North Dakota, Montana, Idaho, Wyoming, Colorado and return to Florida in significant part because of the unacceptable behavior of this engine. The observations below briefly explain the great difficulties I experienced driving this motor home.

1. During moderate to fast acceleration the engine rpms increase to 2,000, the governor audibly takes control, then after a delay the transmission shifts up one gear.
2. During no load down hill acceleration the engine rpms continued to increase beyond 2,000 and the transmission shifted at 2,100 without the governor controlling the engine.
3. During normal driving with the engine brake off the transmission appears to perform properly.
4. With the engine brake on at highway speeds of 70 – 75, when the accelerator is released the following happens:
a. Engine brake light goes on
b. Transmission down shifts two gears
c. Engine rpms rise to 2,300
d. Engine brake does not engage until rpms drop to 2,000
e. At 1,900 rpms the transmission down shift another gear, rpms rise to 2,300 and the same cycle repeats
f. During most of this time the engine brake is not working.
5. At slower speeds the same problem occurs, for example, on an Interstate highway ramp transitioning from one interstate to the next I was driving at 40 mph. The driver in front of me slowed excessively. I backed off on the accelerator, the engine brake engaged, rpms rose to 2300. I was unable to increase speed until the rpms dropped below 2,000.
6. Anytime the engine rpms are above 2,000 and the engine brake is on the coach will not respond to accelerator input and turn off the engine brake, or shift the transmission up a gear. Turning off the engine brake switch has no impact. Trying to manual shift the transmission has no impact. In the example that began at 75 mph, the coach continues to slowly reduce speed until 2,000 rpms was reached, which is approximately 60 mph in 4th gear and took almost 14 seconds.
7. I had an experience while driving in the left lane at 75 mph, I needed to slow to 70 mph and merge to the right lane behind a semi. I was unable to do that. The coach continued to slow to 60 mph, causing traffic problems behind me, and the opportunity to merge right disappeared as traffic closed up.
8. Some times it is possible to very carefully feather the accelerator, while watching engine rpms, and avoid down shifting two gears, thus maintaining rpms at 1,900 where the engine brake will work. In those instances there is no apparent performance difference between low, medium or high engine brake settings. This is a very difficult task, impossible to consistently perform or maintain over any extended period of time.
9. And, here is one general example. Due to the unusual behavior of this engine, the trip from Athens, AL to Dothan, AL, which is less than 300 miles, took 9 hours. There was one fuel stop and two 10-minute breaks. Driving the north Alabama hills, and Birmingham and Montgomery traffic was very difficult. Frequently I was suddenly slowing traffic behind me down by 10 – 15 mph when the engine brake engaged. I’ve driven this route many times in a coach with the ISX15 engine and it should have been done in 5 hours, including two 10-minute stop
10. I am concerned about potential engine damage being caused by the repeated over-revving of the engine.

Over the past 11 years I have owned a driven three motor homes with the ISX15 engine all over the country including many trips to the Rockies, numerous high mountain passes, I80 to California, etc. with long descending grades as step as 8 – 10%. The ISX15 performs admirably. It is easy to use the engine brake in all conditions and manage the vehicle’s speed.

The current performance of the ISX12 engine is a dismal failure compared to the ISX15. Driving in traffic with the engine brake on is hazardous. Plus, it is impossible to manage vehicle speed on downhill runs using the engine brake. As it currently performs I would never consider driving this coach in mountainous regions. That is a major problem for us. One of our biggest uses of a motor home is to tour the western states.

Do you have a road speed limit programmed in this vehicle?
Does it act correctly with the engine brake enable switch turned off?

[Steve Kieffer]

No road speed limit on this vehicle.


With the engine brake off, the transmission still behaves the same on acceleration, but does not down shift to high rpms when I back off the accelerator.