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Pizote 10-23-2018 09:02 PM

DT466 Engine Fan behavior
Ok. So just picked up my bus and drove it home 2300 miles.

The first day and 800 miles, I must say I didn’t notice the fan come on but once. Maybe I’m making it up because I honestly don’t remember.

I cruised all day at 65mph and about 2450 rpm. Mostly - make that all flat in Louisiana and Texas. Which explains why I didn’t hear it. As I remember the temps were around 180-185

The second day (25 hours and 1600 miles) when I got to New Mexico, Arizona and California, I noticed the engine fan was coming on during slight uphills. I thought it might be the altitude. Then started looking at the temperatures more closely. All of the starts seemed random as they would come on anywhere between 185 and 205 and off between 175 and 185.

When I was on the flats normal temp was around 185 a 2450 RPM. When idling it went down to 165.

So that’s the behavior. When the fan goes on, it definitely cools the water temp - visibly. I can see the gauge move until it shuts off. Then when it stops, the temp usually jumps by 5 and then slowly (not visibly) creeps back up to higher temps.

Can anyone tell me what the expected behavior is? It seems like it goes on randomly at various temperatures. Which is weird.

If this is within normal behavior then so be it. Just posing the question.


Additional info: I thought it might be the A/C but I turned it off and no difference. So I tried circulatin the heat pump trying to get the coolant to move through the system and there was no difference there either.

cadillackid 10-23-2018 09:19 PM

your buys being a CE style likely has a viscous fan clutch.. they work by the temperature of the AIR coming from the radiator.. so sometimes outside temperature affects it... since your turbo intercooler is in front of your radiator, climbning a hill means the turbo is creating more boost = hotter turno intercooler.. thius hotter air coming into the area of the fan. regardless of water temperature.. the yway you describe it sounds exactly like I expect a viscous fan to work (and the way it does on my DTA360).. the Air-Conditioner shouldnt affect it as your condensors are underneath vs in front of the radiator.

Pizote 10-23-2018 09:29 PM

Thanks CadillacKid!

You are a wealth of info. I figured you would be the one to answer.

I'm sure as this is all new to me, I will have a bunch of questions answered similarly to "this is exactly how it should operate".

cadillackid 10-23-2018 09:35 PM

these busses are a never-ending learning curve.. unlike consumer vehicles, literally EVERYTHING could be SPEC'd and optioned differently instead of a couple columns of options, there are pages and pages of different options on school busses.. I swear almosat every one of our busses is slightly different from another..

ive got 3 busses and each one of them is 120 degrees different from the other.. LOL


alexzckary 10-24-2018 03:40 PM

same situation
Mine is a 96 mechanical dt466 and well for awhile I thought the fan clutch was bad but mine doesn't kick in till like 215 or so and drops out at 190 however sometimes it will be in for no reason but has never gone dangerously high so It just kind of does what it wants but still kicks in when I really need it to so

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