Temperatures

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Bob T

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Joined
May 20, 2014
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347
Bought and hooked up a Scangauge D so I no longer have to rely on not so accurate dash gauges.
Have it set to show coolant temp, trans temp, boost and average mpg.

Coach is Freightliner chassis, Cummins ISL 425hp with Allison 3000 trans.

What would you think average running temperatures of coolant and transmission..

What about high temps where I should start to be concerned?

As always, thank you for your input..

Bob
 
Ours has the 450 horse Cummins and the Allison 3000, so we're pretty similar. I'm using a Silverleaf VMSAir to monitor all the engine and transmission parameters. Under normal conditions, the engine coolant temp runs about 195 degrees, and the tranny coolant hovers around 192 degrees. The highest engine temp I've ever seen was 221 degrees while towing our 5000+ lb car up a 9% grade when it was 105 degrees outside. I manually downshifted a gear and the temp immediately dropped to 214.

I've hit 217 degees a few times while climbing 6% grades in 100 degree temps (towing) but I've never seen the tranny temp go over 205 degrees. When driving on level (or nearly level) roads in 100 degree temps, the engine temp stays around 200 degrees, and the tranny stays at about 195 degrees.

NOTE: Keep in mind that ours is a DEF engine, and yours isn't. They may be designed to operate at different temps.

Kev
 
The cooling system on my [former] 2004 with Freightliner-XCM chassis and ISL had a variable speed fan and the ECM allowed the cooling system to range anywhere between 165 (where the thermostat opened to allow coolant circulation) and 202 (where the fan went to full high speed). My tranny generally ran from about 172-190, but sometimes as low as 145 or as high as 195. However, if the dash a/c was running, the ECM kept the radiator fan running to assist the a/c condensor and the temps stayed pretty much in the 175-182 range except on long grades.  I inquired of Cummins and they said sustained engine temps up to about 206 were fine with them and briefly higher temps were no worry either.
 
I have the ISL 425 in a 43 ft Monaco Camelot. Towing our jeep I normally see 195 to 198 on the engine and tranny. Climbing in 100+ weather I've seen 214. Engine heats up faster than the tranny, but cools down faster also.
 
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