Community Forums

tiredvet · 05-20-2016, 05:35 PM

Could use some helpful info on when the radiator fan is to engage? I have had our coach for over 4 years and never has the 350 ISC ever over heated. The hottest temp that I have seen was 210 degrees towing up a 9% grade. I started the coach today and let it idle for over an hour on high idle in hopes to see and hear the fan engage.It never got over 185 degrees and the fan never spun at all.Is this normal or do I have an issue? I have had a few rigs in my life and most would show a cooling problem real quick.

Old Scout · 05-20-2016, 05:46 PM

I am sure by now you have read enough on line here to know that you have a mechanical wax valve interface between your engine's need for cooling and the hydraulic fan motor. Engineer Mike has covered this at length in a number of posts. These wax valves seem to vary on specs as to when the fan will activate. The specs suggest a minimum fan speed regardless of engine temp but the fan on my 03 ISL400 remains motionless until the engine is close to ops temp. Since your engine remains at about 185 and never overheats--it sounds like all is well. However, since there is no interface between the wax valve and your dash A/C, your A/C condenser on the radiator stack will not always get adequate air flow, except during fairly warm ambient temps/engine op temps. Not so bad if you live up north, not so good for us folks down south.

tiredvet · 05-20-2016, 06:34 PM

Thanks Old Scout.I seem to be looking for issues where there are none.

SteveS · 05-20-2016, 07:36 PM

Tiredvet - Mine turns at a relatively low speed from startup and goes into turbo when needed. However, unless it is under a heavy load and it is hot outside, it will never get hot enough at idle. Cannot even get the temp up to normal just idling or fast idle.

Old Scout · 05-20-2016, 08:27 PM

No problem--I have a tendency to let "perfect become the enemy of the good enough." Sometimes it gets me in trouble [smile].....

EngineerMike · 05-25-2016, 06:15 PM

There is no turbo at idle, so temps can't get above about 185 (naturally aspirated diesel ignition at idle on my previous coach was ~175)
The wax valve kicks on starting about 190 iirc, so minimal fan at idle.