Normal Transmission Temperature

[steve zannella]

My MH4000 transmission temperature varies with ambient temperature as much as 40 degrees. On cool days, 50F, the transmission will operate around 180F to 190F and on warm days, 80F, the trans will be 215F to 225F.
While my coolant varies from 185F to 190F.

Is this normal, or should I be concerned?

[Jerry Emert]

Mine does the same thing.  In the 90s outside it has gone as high as 256.  It worried me at first but after 3 years and 10K+ miles this summer I'm used to it.
Jerry

[Gerald Farris]

Steve,
What type of transmission cooler do you have?

Gerald

[steve zannella]

Gerald

I only have what came standard with a 2004 marquis c12. I do know the the transmission has transynd lubricant and the shift control shows level OK also I verified level OK on dip stick.

[Gerald Farris]

Steve,
Beaver, SMC, and Monaco used 4 different transmission cooler set-ups over the course of 20 plus years of diesel pusher production, and I can not be sure which cooler was used on each year's production especially since some coaches have been modified through their 10 to 20+ year life span. Therefore, I ask you which cooler you have to properly answer you question.

The first and most consistently used cooler through Beaver (original founders) and SMC production was a liquid to liquid cooler in the radiator return hose. These transmissions have a very stable temperature that is usually under 200 degrees, and if you have this cooler, you are running too hot. This cooler was also used in some Monaco production, but Monaco also used a liquid to liquid cooler in the radiator tank that does not cool as well as the previously mentioned cooler and these coaches run about 10 to 20 degrees warmer. Some Monaco coaches have an air to liquid transmission cooler, and many of those coaches run too cold, especially in the winter for the transmission to reach operating temperature. Also, there were also some Monaco built coaches that do not have a transmission cooler, and if that is your coach, you are running at the expected temperature unless you install a cooler.

Gerald   

[Al Lewis]

Mine does pretty much the same thing. In Texas summer heat I watch it close. At long stoplights I will shift to neutral which stops a rapid rise. Traffic jams are also a problem. It seems to have gotten worse over the years. I just changed to transynd a couple years ago but I really did not see much improvement. Recently I tried washing out the cooler but doubt I did any good. I believe mine to have the air cooler mounted to the rear of the rear radiator. Engine coolant temperature has been very well controlled.

[Bart Mix]

I just completed an Engine Cooling Fan replacement (results posted on the BAC site). My transmission temps had been gradually increasing on my last summer trip to up to 213 degrees. I have the factory tranny cooler bolted on aft of my rear engine coolant radiator. After replacing the fan blade & cleaning of the 3 coolers bolted together (CAC, Engine coolant radiator, & tranny cooler) from the engine side, my tranny temps have been running 15-20 degrees cooler on my most recent trip to Florida. My engine coolant radiator was the most dirty & probably had an impact on the tranny cooler effectiveness? Having a full 8 blade fan rather than the broken fan with only 7 blades helps too!
Bart from VA