Allison Trans Temps

[Jim Shaw]

I have noticed that my trans temp are reading higher than normal. I think it was always less than the engine, but lately it has been running 10 to 15 degreess higher. The engine stays around 180 and the trans is getting up to 195 and over 200 if in slow stop and go trafic. The fluid has been changed and is full, no burnt smell. The air temp here has been in the 90's if that makes a difference. Could this be the start of a problem?

2003 Beaver Monterey
ISC 350

[Bruce Benson]

I have noticed mine seeming higher as well.  I attribute it to three factors.  The main one is that I am driving faster.  Five miles per hour seems to make a significant difference in the temps.  The second is that it is hotter outside.  Due to circumstances that I am not able to control, I am having a difficult time this year following Gerald's counsel on staying out of the heat.  Lastly, I probably never watched it to the extent that I do now that I have started worrying about it.  

Physically, if the transmission is producing heat, it must run a few degrees higher than the average coolant temp.  The coolant will always heat the transmission up to the coolant temp level. What ever the transmission is coming up with must be dissipated above that.  The location of the sensors will have an affect on the differences that we see.  

As long as the numbers are safely below the 230 mark, I doubt that you will get much concern out of your Allison dealer.  An oil analysis at the next filter or fluid change (or before if you are really concerned) might give you some insight or peace of mind as the case might be.

I would also clean the exterior of the radiator throughly and have the fan function checked.  

[George Harwell]

Blowing hot air on a "cooler" just doesn't make a lot of sense in most cases but that is what we Monterey owners ended up with. Your driving speed has a lot to do with the temp. If for example you are driving at 62 mph and the temp is 195 select 5th gear and watch the temp start falling due to less torque in the lower gear. In your case the fan runs constant with the eng rpms unless it has been modified  so heating in stop and go traffic is usually normal due to low rpm and airflow. I select neutral when caught in a traffic jam especially in hot climates. While your temps are slightly higher they are well within the specs for the transmission. It sounds like there may be reduced airflow through the radiator so that is where I would start my investigation. Check the crankcase breather tube to insure it isn't blowing through the radiator. On my 03 Monty I installed the Horton fan and relocated the tranny cooler to the engine bay where I mounted an electric fan. Now I can travel the mountains and deserts in the summertime without fear of overheating. Your problem sounds like the sniffles instead of the flu so I wouldn't get overly concerned if it doesn't get worse. If you are running "Transend" it is not a problem.

[Richard And Babs Ames]

Our old Baronet used a heat exchanger that engine coolent ran through so the engine and transmission stayed about the same.

Our current 97 Patriot uses a cooler mounted in front of the charge cooler on the side and it ran from 180 to 200 degrees per the Silverleaf until we changed to Transynd and we average about 20 degrees cooler in all applications.

[Gerald Farris]

It is normal for the transmission to run hotter in hot weather or in stop and go conditions. When a coach is stopped and in gear with the engine running, the torque convertor creates a lot of heat, so the transmission temperature will be higher.

The temperatures that you gave are not too high, but if you are not running Transynd in your transmission, I would change to it at the next service interval.

Gerald

[Dave Tanchak]

Ok... If the trans cooler is behind the rad... what is the cooler in the front of the coach behind the front bumper fascia?  It has a electric fan on it too.  A/C?
Dave.

from sunny South Lake Tahoe, 85' with the threat of thunder boomers!

[Jim Shaw]

Dave, I believe you are describing the dash A/C comdenser and fan.