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Bungeekord 05-28-2017 08:17 PM

improving my cooling '96 T444E
This thing just had a new water pump replaced last summer, the mechanic said the fan clutch seemed tight, no play. But it still climbs to scary temps on hills with nothing in it, and were planning on going cross country this summer with it. Would love to upgrade the cooling system, possibly to an electric multi-speed fan system, but perhaps a complete cooling system flush is in order first?
Obviously, we changed all the coolant when the pump came off, and it didn't seem to have much sludge in it at all, but perhaps the radiator is clogging up? She's got around 130,000 miles i believe...

Ideas and suggestions very welcome.


- Ben

EastCoastCB 05-28-2017 08:20 PM


Originally Posted by Bungeekord (Post 206278)
This thing just had a new water pump replaced last summer, the mechanic said the fan clutch seemed tight, no play. But it still climbs to scary temps on hills with nothing in it, and were planning on going cross country this summer with it. Would love to upgrade the cooling system, possibly to an electric multi-speed fan system, but perhaps a complete cooling system flush is in order first?
Obviously, we changed all the coolant when the pump came off, and it didn't seem to have much sludge in it at all, but perhaps the radiator is clogging up? She's got around 130,000 miles i believe...

Ideas and suggestions very welcome.


- Ben

How hot have you seen it go?
My 444E and pretty much everyone else's seems to run a bit on the hot side, especially over 55 mph.
Just the nature of the beast, really.

gbstewart 05-28-2017 08:25 PM

what temps are you reaching? if i remenber right mine reaches 211 and the fan cuts in and shuts of 204 , I have a horton electric clutch fan.
You might want to try a engine\rad flush, and t-stat, as well as clean the rad fins, you may have a air lock , so bleeding the system may help

EastCoastCB 05-28-2017 08:59 PM

^^ dang, and I get worried when mine goes over 180 or 190.

cadillackid 05-28-2017 09:08 PM

ive been pretty much deep into this with my 444E..

for one, read the computer, dont rely on the dash gauge... mine reads too cold at lower temps and too hot at higher temps.. the dash gauge is just a representation of the computer sensor (the dash is on the CAN).. Navistar gauges are not real good..

Next, high RPMs will make it run hot.. seems a facxt of life.. to say navistar never built trucks that overheat from the factory is probably the case.. as these are school busses, designed for slow and go routes.. the 444E runs very cool in those circumstances..

Next, if you have a Viscous fan clutch. (it has the fins on it and the little coil on the front).. it is likely either no good, the wrong part, or misadjusted, .. if tyou arent hearing the road of a fan and tyou are approach 215 degrees.. the clutch needs attention.. 90% of the replacement fan clutches for 444E's are made and sold by Kit-Masters.. the clutches are built by Borg warner, but KM sets the temp too high..

the split radiator allows for too much "cool" air to enter thestream and never winds that coil on the clutch out to engage the fan...

if you have an ELECTRIC Clutch and its connected to the factory computer it will engage at about 212 degreesand drop out about 205-207.. thats an upgraded Horton clutch.. a working Viscous clutch should do the same or earlier...

the more I read o nthe subject the more I also learn that aftermarket replacement radiators. are reported nbot to cool as well as OEM.. not sure why but real-world school bus fleet masters came to that consensus.. a huge portion of aftermarket rads for these are made by MODINE...

I did some extensive measurements and upgrades to the cooling system on my bus.. I went from running close to 220 and having to slow down to 55 MPH in 90 degree heat to seeing a Max temperauter of 217 in 103 degree heat (not heat index, actual heat).. at 65 MPH.. so while it didnt completely solve it, it helped..

I replaced my water pump, oil pump, completely flushed my system and replaced with a 40% coolant / 60% water, + watter-wetter and (AMSOIL hugh performance ELC coolant), my MODINE radiator was boiled and cleaned.. I also repalced my viscous clutch with an electric Horton EC-450 and a 9 Bladed fan that moves more air..

my Now project is reducing my RPMs.. im installing a 6 speed allison overdrive auto transmission which will reduce RPMs and gives me Lockup... my guess is ill run cooler yet..

I have a thread somewhere where I chronicled my cooling system updates... and somewhere I know I pposted how to adjust a fan clutch temperature.. if not i need to do that...


Bungeekord 05-28-2017 09:22 PM

how do i "read the computer"? Ive just been relying on the dash gauges, but yeah last summer when we moved it was getting upwards of 215 then we'd pull over. Highway driving, trying to keep RPMS down but those hills in summer really made the temps climb...

On one particularly long and steep pass it made the alarm go off before I could pull over, it was not pretty, lost some coolant, but was able to cool down pretty quickly after that, replaced all fluids, etc. so hopefully there was no long term damage done (fingers crossed).

I dont hear real well, and it seems to me whenever I'd pull over and flip the hood to let it cool the fan was ALWAYS running, even once it got down to 180 or so (according to the gauge) so I'm not sure how the fan clutch works I guess. im pretty sure the thing spins even right after I start it!?!

Im interested in the electric option, but might look into getting the rad cleaned as well. how much should this run me?


Tango 05-28-2017 09:26 PM

Yes...check the rad itself. It has probably never been flushed in its' career and could well be full of crud.

gbstewart 05-28-2017 09:46 PM

I have a scan gauge and that's how get the temp readings, in all the kms I put on my bus, the temp is always run the same, up hill, hot weather, or running wide open hwy speed, high 211- fan cuts in , shuts off 204 you can hear that Horton roar when it cuts in.

cadillackid 05-28-2017 09:51 PM

the alarm goes off at 235.. if it goes off when you are climbing.. theres a good chance your oil temp is at 245-250.. your oil loses viscosity and breaks down .. your Oil Pressure will begin to erode when you get up that high too.. the oil pressure alarm comes on if your oil P drops below 25 PSI and your engine is over 2000 RPM.

a viscous fan clutch will engage fully (fan roar) for the first few minutes you drive it when it is cold.. this is by design. if you dont hear that fan roaR again by the time you have 215 degrees then somethiong is broken.. either tha radiator is completely clogged (remember that clutch measure AIR TEMP from the rad.. and it shares that same air with the turbo cooler (noticve your radiator is split in the middle.. you only have a 1/2 a radiator... ).. or that clutch may be misadjusted or no good.. or the wrong part was installed..

here is what a kit-masters replacement clutch has for its temperature adjustment..

that green mark is factory at 170 degrees F AIR TEMP.. FROM A 1/2 RAD 1/2 turbo cooler.. each little notch is 10 degrees F.. you can move that down (to the left) to lower its ON temp..

below is the Horton Electric clutch.. its temperature is controlled by either the engine computer or by an external... these can be retro-fitted onto older busses.. if your chassis is 1997 or older then you use an external device to turn the fan on / off (or if you want complete control over it.. like i did)...

this is a demonstration of the Horton EC-450 as I test ran it right after installation.. Im using a Dakota Digital controller so i can controller when it turns on and off ..

cadillackid 05-28-2017 09:55 PM

you can hear the Horton pulling in and out in this video.. its LOUD when it runs..


oricha1984 05-28-2017 10:01 PM

that video looks so cool man; computer and tablet connected to the bus.
i've never seen that before.

Bungeekord 05-28-2017 10:49 PM

hhmmm, dont think Ive ever heard that thing kick on like that. somethings up I guess. Damn. Will look into this. Should I start with trying to adjust the temp settings on the clutch?


Bungeekord 05-28-2017 10:54 PM

and is an oil change in order if ive gotten it so hot? How quickly will it degrade once its reached higher temps? Pressure still seems good or at least normal to how its always behaved. But now Im doubting the accuracy of these gauges.

How did you connect all that to the tablet?

cadillackid 05-29-2017 08:12 AM

the least cost way to connect to your engine computer is to buy a ScanGauge 'D'. (the diesel J1708 version).. it doesnt have as pretty a display as a tablet but it does the Job.. you can show different parameters on its LCD screen.

your oil probably wasnt damaged.. it doesnt lubrucate as well when it is at those temps.

transmission fluid that hot does get damaged.. from what I understand engine oil does not.. though I recommend clean oil in ANY HEUI engine (T444E, DT466E,Cat-3126, VT-365) are a few

as a first try I would try adjust the temp down on the clutch if you have the adjustable type. it IS possible to get an iphone or a go-pro in front of the clutch to take a picture and see what you are dealing with. my hands are skinny so I was able to further adjust mine down. which greatly helped.. but still the fan wouldnt run as much as it needed to in florida heat... so thats when I swapped out to the Horton CLutch and an upgraded Plastic Fan blade which Navistar says moves more air.. the plastic fan can be used with either type of clutch... its definitely louder and seems to pull more air..

I drive this bus all over the bus and at highway speeds. im RPM in the 2400-2500 range to keeo it at 64-66 MPH.. which seems to be the point that these engine get hot.

the AT545 transmission doesnt help as that unlocked TC is using up some power..

since my AT545 is going Defunct i am replacing with Allison 1000. that will slow the RPMs and lock-up.. will see if that makes cooling better..

but my current system DOES work as I no longer over-temp.. i just run it close to the edge now (217 max). navistar said 217 is warm but not to worry.. I more like 195-200 for a diesel..

when I first got my Bus in texas, I tried to drive 65 on the highway and the temp quickly climbed to 225. so I dropped to 55 and it ran at like 220-225.. the original fan clutch was not turning fast and was not adjustable.. it was Bad.. so i replaced it with the Kit-masters (shown in my pic) and that helped but didnt solve the issue but it was driveable under most conditions... then I did the Horton update..

there are others on here working this from different angles.. ie trying to find full-size radiators that will fit. and have the turbo-cooler in front of the Rad.. (the way it shouldve been designed).. at one time I looked at Auxilliary radiators ...

I will know more once I get my new transmission installed also.. to see if the lower RPMs help.. that project is in progress.. i'll be going to florida this week or early next to get it and then proceed to install it. I may start the take-out of the old today


pegabus 06-14-2017 10:18 PM

Same problems here
Wow, I seem to having the same experience you been having. 2000 T444E RE bus runs hot 220 on hot humid days only, 230 up long grades. New water pump, thermostat, coolant flush, coolant filter, reservoir pressure cap. no change or improvement. Installed the Horton electric clutch, plastic fan, and manual switch to fire up the fan when ever I wanted. Improved for 2 years but problem came back. Checked for head gasket leak, performed coolant pressure test everything was fine. Down to one culprit, the huge truck sized radiator on the RE models is seriously big. Pulled it brought to a radiator shop to have it tested, then re cored. The re-builders said entire rows of the radiator was plugged so i believe I'm on to something here. Just got the radiator back, putting it in over the weekend. This better work for $995.00 re-core bill. Quick Question Christopher you don't happen to have a fan dimension or part number, that fan seems bigger than the one I got. Also what Thermostat temp are you running, I'm still at the factory temp, did you lower yours

cadillackid 06-15-2017 04:28 AM

My plastic fan is just shy of 24 inches diameter.. I'll look the part number up for it, I may have posted it in my thread where I did the cooling system upgrade. It ended up in the licensing and titles section,"got a bus in tx" ,

I'm different though as it's a Comventional with the split radiator and turbo cooler.. and had an at545 trans so on the highway I was running near max rpm which I hear isc a waste and heat maker in a 444e. I'll soon know if rpm was an issue , I'm doing a tranny swap.
I went to a 180 Tatat. Also switch to elf coolant and lower the mix slightly unless you are so far north that you get way below zero in winter.

ggaabe 09-08-2017 10:51 PM

I'm having the same issue. Climbing mountains in Colorado, it also seems as though the turbo has stopped working, but we're not even sure because we're just seeing the engine struggle so much. Even at night in the rain, we're overheating going up the hills around the rockies.

cadillackid 09-09-2017 05:43 AM

These engines definitely struggle on hills, if you can get access to a scan tool you can see if the turbo works as the boost is one of the PIDs you can read out.
Ultimately if your temp is up and your fan isn't blasting then start there .

I've run some 6 and 7% grades in my shortie since I did cooling and trans and I still warm to maybe 208 but not over temp. If you can downshift , run slower and the engine load PID off the 100% peg you'll cool right down. Move your tranny cooler from the stock radiator to an external reduces the amount of tranny heat you have to dissipate in the radiator as well.

brokedown 09-09-2017 01:02 PM

Hopefully obvious advice:

Slow down. Don't run wide open throttle up these hills at the expense of your temp gauge. Downshift to keep the motor where it makes power without lugging it. Don't worry about being slow. Remember your fan is driven by the engine and spins at a speed relative to engine rpm. Don't cook your motor, the T444E doesn't handle overheating.

cadillackid 09-09-2017 01:11 PM

Yes and no to RPM. The 444E doesn't like rpm over 2100, it also doesn't like being lugged heavily, yes to slowing down and driving at a gear that leaves your foot at 85% or less throttle. The 444e, at least my post 1996 has a pedal map that gives you a lot of extra oomph in that last little bit of pedal , keep it out of that oomph zone and you won't over temp . If you have a 545 trans you may be best off in 3rd gear hold at 2000 rpm .

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