Cummins ISC 360 HP,when engine RPM lugs down during climbing, engine runs cooler.
This is my first post on this forum. My main language is German, so please excuse "weird" sounding sentences.
Our DP: Damon Tuscany 42 RQ with tag axle, Cummins ISC 360 HP on Freightliner Chassis.
Main Problem was, as experienced by other members, is the constantly repeating temperature fluctuation during climbing hills, which is almost 30 deg. Celsius. This is ca. 37% temperature fluctuation, based on the normal operating temperature of 80 deg. Celsius (180 Fahrenheit). During climbing, engine temperature rises, fan kicks in, engine cools down rapidly and fan kicks out, engine temperature rises again and this cycle continues until reaching the top of the hill.
However, at one time, just by accident, I was very easy on the accelerator, transmission on Economy Mode, while climbing a steep hill, the rpm dropped to 1150. At this point the engine temperature started falling and stayed at around 90 deg. Celsius with out the fan kicking in. At the same time, the indicator for "instant fuel economy" was reading much better values than when operating within 1400-2000 rpm range.
I did duplicate this "phenomena" intentionally in the next climbing, and sure enough, it repeated the same behavior. When engine lugs down to about 1150 rpm, mostly in the 3 rd or 4 th. gear, the engine temperature will not increase that much and with out the fan kicking in. I can't figure out, why the engine is acting this way. It seams to be against all odds.
I usually try to exploit this phenomena while driving through the Canadian Rockies.
I am sure, this is not harming the engine or the power train, as either the engine ECM or the Transmission ECM will not allow operating in damaging rpm range and would force a shifting in to a lower gear.
Would be interesting to know, if other members have experienced this situation as well?
Monika and Robert,