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Old 05-27-2014, 11:18 PM   #1
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Allison temperature questions

I have a 2008 Mandalay Presidio with the Cummins 360HP ISC Turbo Diesel engine which is mated to the Allison MH3000 6 speed electronic push-button automatic transmission.

When engine and tranny are cold (eng temp. 100+, tranny temp. 80-100) and I begin to accelerate, the tranny will not shift out of 1st and the engine will rev up to 25-2700 rpms, then drop. The engine continues to rev up and down like this and the tranny will not shift. But, when the tranny temp gets to 115+, everything runs fine.

My questions are... Is this normal for a cold tranny or is something going on? Do I need to let the engine/tranny warm up more?


- 2008 Mandalay Presidio 38D - Cummins ISC 360hp, 1050ft/lb torque - Allison 3000 trans.

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Old 05-27-2014, 11:53 PM   #2
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Allison trans manual lists temps of below 19f for a restriction of shifts.
I've never had the condition you describe , and I have started out in temps below 19f after a short warm up , but I had the block heater on, and went 1/4 mile through the RV park before I got fast enough for a shift.
Possible fluid temp sensor fault.
Do you have service records for the trans? Manual has a warning about cold operation with non approved fluids.


for a free download of the manual if you don't have one. Too big for me to post here.

99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
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Old 05-28-2014, 02:38 AM   #3
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This is NOT normal.

Are you holding the throttle pedal down while the engine is revving up and down?

When hot, what engine revs does the transmission shift into 2nd gear?

Are the shifts smooth once everything is hot?

Have you used the push-button shifter to check the transmission for fault codes?

What does the engine pull like on hills?
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Old 05-30-2014, 02:17 PM   #4
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Sounds like you may have a bad sump temperature sensor. I recommend you have it tested for fault codes at a certified Allison dealer or distributor.
Tom Johnson
Former Allison Transmission Fluids Engineer, "Mr. TranSynd"
President and Founder at JG Lubricant Services, LLC
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Old 12-30-2014, 05:41 PM   #5
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My motor home has a 2006 Allison 3000 transmission and Silverleaf monitoring system. Normal operating temps are in the 180-190 range. Last two days of travel the transmission has maintained those temps for several hours of travel and then gone down to 140-150 degree range where it stays for the rest of the days drive. Worse, my rolling mpg plummets from 8.5-9.5 mpg range down to 5.0-6.5 range. No external factors (terrain, wind speed, wind direction, air temp) are variables that could cause this drop.

Any help would be appreciated.

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