Normal Allison HD transmission operating temperature range is 160F to 200F. Anything over a sump temp of 250(f) is considered excessive. On newer transmissions the ECU will inhibit operation in higher ranges if sump temp reaches 262 F
I did clean the radiator with simple green before we flew back home so hopefully I'll see lower temperatures.
Is there anyway to tell whether I have Transynd or not?
That's a very good question. You probably can't use color because of the mixing of the new with the old. Transynd is noted for its extreme heat tolerance (330F intermittent), so perhaps a frying pan heat test? Take a sample from your transmission and compare it to a standard oil sample as you heat the pan? I have seen heat tests with synthetic versus mineral engine oils, and the time difference in the oil starting to darken is fairly significant. Be careful whose frying pan you use
We cored the radiator on our bus after you were here and took a 1000 mile "shakedown" trip. Tranny (740 4 speed ) had been running under 200 but on this trip ran up to 245. I talked to Allison and they told me anything over 220 and the fluid "cooks" and looses its viscosity. I thought maybe when we put the radiator back in that they had blocked a line (transmission coolant runs through a separate section in the main radiator) Long story short, we dumped the tranny fluid and also took the pan off and cleaned the filter in the bottom of the pan (which a 740 4 speed has0 that had some gunk on it. Took it out for a hard test run and firewalled it for 100 miles in 93 degree weather and never got above 190 with new Transynd and cleaning of the filter. Not sure if your 6 speed has a filter in the bottom of the pan (Allison could tell you), but if so, it may be partially clogged as mine was which would be an easy fix versus a new transmission.
Ok my new bushing trip yesterday I noticed that the trans temp settled around 218-219…. Seems rather high to me. Would not go over 219 on the BlueFire. I asked my wanderlodge buddys what theirs run at and they say like 180. Should I be concerned??
(06-01-2026, 05:04 AM)whited44 Wrote: Ok my new bushing trip yesterday I noticed that the trans temp settled around 218-219…. Seems rather high to me. Would not go over 219 on the BlueFire. I asked my wanderlodge buddys what theirs run at and they say like 180. Should I be concerned??
That is getting high, 225F and you should be pulling off and letting it cool down.
I think mine has its own cooler mounted just in front of the drive axle with electric fans, at least I think it’s for the transmission, it might be for the hydraulics. I have been wanting to test the fans to make sure that they work. Maybe yours is not cooling properly.
I have also seen a leaking CAC cause everything to start to heat up.
(06-01-2026, 05:04 AM)whited44 Wrote: Ok my new bushing trip yesterday I noticed that the trans temp settled around 218-219…. Seems rather high to me. Would not go over 219 on the BlueFire. I asked my wanderlodge buddys what theirs run at and they say like 180. Should I be concerned??
That is getting high, 225F and you should be pulling off and letting it cool down.
I think mine has its own cooler mounted just in front of the drive axle with electric fans, at least I think it’s for the transmission, it might be for the hydraulics. I have been wanting to test the fans to make sure that they work. Maybe yours is not cooling properly.
I have also seen a leaking CAC cause everything to start to heat up.
My Wanderlodge never went over 200F on my silverleaf, even for long up hills. I haven't done any major hills in the Newell, but at 80 mph and slight extended grades it creeps up to 205.
Low fluid can cause higher temps.
I am a huge fan of Transynd and will service the Newell transmission this summer.
One modification I am going to add for sure, that I did to the Wanderlodge, was add a thermostat controlled Derale fan to the curb side air louvers. This makes a huge difference in the summer. It's like a booster for cooling the radiator, CAC and transmission. I put the thermostat on the engine ceiling so that it was auto. It keeps the engine cooler and reduces heat build up in the rear of the coach. I'll post a few pics when I get it installed in case anyone is interested.
Thanks!
Mark Kitchens
Athens TX
2003 Newell #676
2016 ERA 70C
1995 Wanderlodge WB
1979 Wanderlodge XV
1973 GMC
