Transmission Over Temp Message while Towing

[LIDR]

I have a 2007 National Dolphin, Workhorse Chassis (8.1 ltr) with a 6 speed Allison Trans. On 3 separate occasions a message on the instrument cluster has come on reading "Check Transmission Temperature" during the accent of a 6%+ grade and or descending while towing. (The Toad curb weight is 3854)
The message goes off after descending when air gets moving across the front of the motor home
during the down hill run.
The Trans has synthetic fluid in it, The trans warning light (green gear)(not Grade Brake) has not come on during these events and checks OK during a lamp test.
My Instrument Cluster is not of the type (CTP) which can read Power train data messages or I would check the temp.

I have emailed Workhorse with questions about installing an external cooler. Their response is," it is not needed go talk to Allison".
Allison will only comment after they inspect the coach.

Before I turn it over to Allison I'd like to know if any one else has had transmission heating issues while towing up or down hills, or if anyone has installed an external cooler to correct the Transmission temp. heating issues? Any response would be appreciated.

Author: Mike (lidr@verizon.net)

[two2go]

LIDR, over temp happened to me coming up 7% grade to Eisenhower tunnel on I70. Was in 1st gear at 28 mph for most of it. Got warning near top and it stayed in 2nd gear through tunnel. Stopped at east end in neutral for a couple of minutes and went on without further incident.
Took coach into Allison shop and got regular service--fluid and filter change. No problems found. The shop put in regular fluid even though I asked about TranSyn. I guess I won't worry about overheating unless it happens repeatedly and the shop says I have a problem. I may unhook toad next time through the tunnel and let the DW drive it through.

[paz]

LIDR, welcome to iRV2.

If you scroll down to the Workhorse or the Allison Transmission Forums and use the "Find" button (type in "transmission temperature" or "transmission warning" or something similar), you will see others have had the same problem.

The same thing happened to us last year crossing the Rockies. We were climbing a long grade in 1st gear. Our Allegro Bay is 37 ft. long, loaded for full-timing, and towing a Saturn Vue weighing about 4000lb. We have the 5-speed Allison. Fortunately, there was a rest stop within a quarter mile. I pulled in, and by the time we had watered the dog and went to the rest room ourselves, things had cooled down and we were on our way.

I now take it a little easier on the long grades. I try to keep the RPMs below 3800. We crossed the Bighorn Mts., the Absakora Mts., and the San Jauns this year with no overheating.

Check the color of the transmission fluid on the dipstick. Fluid that has been repeatedly overheated will start to deteriorate and turn brownish. Both TranSynd and Dexron fluids are supposed to be bright red. If your fluid is still bright red, I wouldn't worry about it.