02-04-2021, 08:30 PM
Dear Newell Allison HT-700 Series Drivers,
After several $$$$ with the local United Engines facility, we've learned that our coach (#277 1991 model) was broken before servicing and United Engines accidently fixed the problem of a low reading transmission temperature gauge. Our VDO gauge reading matches the transmission oil pan temperature very accurately. After the repairs of cleaning the rear mounted radiator, repairing the many oil leaks, engine computer
cruise control and speedometer outputs, I began noticing the transmission climbing to 210° on the first trip out to Newell for new heaters and other work.
Before repairs it rarely reached 140/160° on the road. This was at 65 mph at about 1750 rpm.
Well turn around and a slow trip back to United Engines. They cleaned and flushed the transmission and road tested OK. So on the road again, the transmission temperature begins climbing if I travel over 55 mph. We finally retrieve the coach in January (parts issue, not Newell's fault!) and return the RV to United Engines. After a two hour test drive and seeing 250° in 62° OAT, UE calls Allison. See the attached Allison manual pages.
It turns out for an Allison HT-41 (700 series), the transmission temperatures can be at 300° and easily at 250° continually. See attached pages.
I hope this saves everyone money and worries. The temperature probe is at the output of the transmission feeding into the radiator which is the hottest point in the system. I've never found the transmission manual in our coach.
Happy road miles to you!
Danny
After several $$$$ with the local United Engines facility, we've learned that our coach (#277 1991 model) was broken before servicing and United Engines accidently fixed the problem of a low reading transmission temperature gauge. Our VDO gauge reading matches the transmission oil pan temperature very accurately. After the repairs of cleaning the rear mounted radiator, repairing the many oil leaks, engine computer
cruise control and speedometer outputs, I began noticing the transmission climbing to 210° on the first trip out to Newell for new heaters and other work.
Before repairs it rarely reached 140/160° on the road. This was at 65 mph at about 1750 rpm.
Well turn around and a slow trip back to United Engines. They cleaned and flushed the transmission and road tested OK. So on the road again, the transmission temperature begins climbing if I travel over 55 mph. We finally retrieve the coach in January (parts issue, not Newell's fault!) and return the RV to United Engines. After a two hour test drive and seeing 250° in 62° OAT, UE calls Allison. See the attached Allison manual pages.
It turns out for an Allison HT-41 (700 series), the transmission temperatures can be at 300° and easily at 250° continually. See attached pages.
I hope this saves everyone money and worries. The temperature probe is at the output of the transmission feeding into the radiator which is the hottest point in the system. I've never found the transmission manual in our coach.
Happy road miles to you!
Danny