Descending Passes causing engine overheating, 2004 Featherlite

[MWSHAWJR]

Have driven from Orlando through Nashville and now near Pueblo, CO. Bus has done great and at road speed and up passes engine temp stays good. However, descending the mountain makes my temp gauge go up quickly and dash warnings appear and bus wants to shut down. Have checked coolant and it is fine.When I make it to bottom of grade, temp gauge returns to normal. Please advise as I need to cross a few more passes to reach Montana and am hesitant to move. Thank you, Mike Shaw... Please ASAP

[truxton]

Mike, your getting up into thin air 4800 ft, did you check your air filter?

[MWSHAWJR]

Thanks, Bernie, air filter looks good!

[dale farley]

Mike, Have you tried downshifting one extra gear? Do you have a transmission retarder or Jake? It is strange it is doing it coming down but not going up.

[truxton]

Mike,

We run the high country all the time and over 5000 ft my motor runs betweeen 201 and 211. Do you have a DDEC 4 ? Did you notice any white smoke?

[MWSHAWJR]

Thanks Dale, I have transmission retarder. Thinking about gearing down to 4 and not using retarder.

[dale farley]

Mike, You might also have an issue with your engine fan. Try running the dash AC so the fan will be on high speed and see if that helps. When you turn on the dash AC make sure the fan is going to high speed. There are so many checks and balances on these systems, it is easy to overlook what might otherwise be the obvious. Don't know why there would be a difference with the fan while going up or down?

[dale farley]

I have always had a Jake, and most of the time I descended steep grades out West, I was in 4th gear.

[MWSHAWJR]

Turned AC on high and fan was spinning fast!

[rfoster]

Having had a 97 Liberty with retarder - I know that the temps are driven up quickly with the retarder on. I recommend you start the top of the pass in 4th gear, retarder in 2nd position and speed at 50 mph and maintain that best you can by applying the brakes as needed. Depending on how long the pass is watch the tach - not over 2000 rpm preferably less than 1700 you may have to increase the retarder. .

Also as the other post suggest - run the Air Conditioner.

With my 06 with the retarder the temps are not an issue as was with the 97 - bigger radiator? Different source for the tranny temp readings? don't know that answer. But I know I can descend Sams Gap (7% grade) on I 26 and never touch the brakes using the retarder, 50 mph, and 4th gear.

Hope this helps.

[Pete]

My coach has a retarder, which will run the trans temp up very fast if not using the proper gearing and retarder settings. (I assume you you have a trans temp gauge and are not mistaking it for your engine temp). Roger is right about the settings. Hope you can figure it out, and let us know what you find. What are the details of your coach....year, converter, engine, trans ect? It would help us help you.

[BenC]

As I think has been mentioned, the transmission oil cooler is engine water cooled, not air cooled, so transmission oil heat is rejected right into the engine cooling system, then is cooled by the main radiator/fan combination. What warning lights did you observe on the dash? The one that looks like a gear is the "check transmission" warning, and will come on if trans oil temp gets to the point of needing to shut the retarder off to protect itself. Look at the message display, in the gauge mode menu, the gear with the thermometer by it is the transmission oil temperature gauge. Generally it will be close (STEADY-STATE conditions) with engine coolant temp (the gauge with a needle in the left section of dash located above the message display).
As was also mentioned, downshifting to a lower gear for long grades will prevent excessive heat being added to the transmission and engine coolant systems.