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Old 06-26-2019, 04:55 PM   #1
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T444E / 545 operating temps.

I what are the normal temperature ranges for a t444e? And 545?

T444e (my normal operating temps are coolant 208-212, oil 210-220)

How high is too high for:
Coolant?
Oil?

Also what temp should the transmission stay below?

Iím in the West Virginia mountains. I need to know what temperature for the coolant/oil should I pull over and cool down.. same with the transmission.
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Old 06-26-2019, 06:34 PM   #2
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those temps are about what I ran with an AT545... the computer rings the alarm bells for coolant and oil between 228-235 depending on which setting it has.. thats the "im too hot do something NOW" warning... oil temps usually run 10-15 degrees above coolant temp if you are spinning high RPMs..



your transmission really likes to be cooler than 220 with standard fluid.. if your engine coolant is already at 210-220 its going tp be hard for the trans to cool off into its comfort zone of 180-200 unless you install an external trans cooler..



that said, i was driving a 40 year old bus across the country last year in the cascades.. my engine didnt put out much power as I just figured.. its an older gasser.. my AT540 was around 200-220.. as i got higher and higher I never thoguht about it but seemed like it was running nicely.. yeah turns out the bus lived its life above 5000 feet so the carb was tuned for it.. at one point I was climbing from 6000 to near 9000 feet... i had it buried, haulin arse... then I smelled trans fluid.. I stopped (my engine temp was a nice 210).. trans fluid was everywhere.. the ground.. the exhaust.. smnoke everywhere.. I hit the trans with the temp gun and I was at like 385.... I let it cool down for an hour and a half.. added a gallon of fluid and finished the next 2300 miles without a hitch (albeit lighter on the pedal)...


so yes overheating a trans can destroy it.. but they also tend to be somewhat more durable than people might suggest at times..



take it easy on it. downshift.. running higher RPMs at lower speed allows the fan clutch on the engine to engage and really spin, as well it also puts less stall load on the unlocked torque converter..

a buried pedal with the RPMs spiking and the bus going slow and in a higher gear tends to heat things up faster ....
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Old 06-26-2019, 07:20 PM   #3
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^this

During hot days my bus will run close to 200 but normally around 190. I don't have a trans temp gauge but I can assume my trans temps are close to the coolant temp. I learned this with driving behavior. Beating on my bus raises the coolant temps and the trans reacts with certain behaviors.
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Old 06-26-2019, 08:07 PM   #4
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Right on thanks for the replies. My transmission temps are 210 at the max, any higher Iíll be pulling over to let it cool. My oil temps are staying in check well below 230. What about the coolant? Should I be worried if it spikes into the 220-225 range for a min or two?
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Old 06-27-2019, 03:34 PM   #5
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Originally Posted by Rogue1bus View Post
Right on thanks for the replies. My transmission temps are 210 at the max, any higher I’ll be pulling over to let it cool. My oil temps are staying in check well below 230. What about the coolant? Should I be worried if it spikes into the 220-225 range for a min or two?
As mentioned before, the ECU will reduce engine power and ultimately shut the engine off when coolant temperature gets too high. As long as the cooling system can take the pressure, you can run it until the lights start blinking.

Is this engine/transmission combo in the bus shown in your avatar? Reason for asking is that I have a lot of experience-based tips to keep the T444E/AT545 cooler in a dog-nose chassis but that may not apply to your bus.

But here is the list for those with a dog-nose:

1)Fan clutch: The engine needs to make a crazy loud fan noise when fired up and when coming down from high rpm. If it does not, change the clutch.
2)Fan: When you change the clutch, upgrade to the never fan with many more blades.
3)Fan duct: Repair the fan ducting so that there is no cooling air bypass.
4)Radiator: Clean the radiator and charge cooler inside and out. A lot of junk gets stuck in the fins over the decades and the charge cooler is usually a mess inside form oil getting into the intake system via the turbo even if the turbo seals are fine.
5)Turbo piping: make sure you are not loosing boost pressure anywhere. Also check exhaust side.
6)Transmission fluid: Changing to a synthetic fluid like Transynd will reduce slip and heat generated in the torque converter. You need to flush, not just drain and refill.
7)Transmission cooler: If it does not already exist, add an air-to-fluid transmission cooler before the transmission fluid gets into the water-to-fluid cooler. That take the heat out of the coolant loop but assures that the transmission is warm enough in the winter.

Before doing these things my International 4700 box van would overheat on steep grades even in the winter. After fixing the age related issues I can now get up the steepest hills in the heat of summer. The whole cooling system is marginal at best and any neglect/wear will push it over the edge.
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Old 06-27-2019, 03:58 PM   #6
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if you are reaching 220-225 and like the last post, not hearing the fan roar then I would be checking the fan clutch... spiking it to 220-225 wont hurt it.. if the alarm starts ringing... (it will be a beep-----beep-----beep--) about ever second and the oil/water (red light) will be lit.. then you need to think about cooling it down..

if you are hauling pretty good.. reduce power and RPMs and it should go away in aminute or so.. you really want to avoid shutting it down unless it continues to spike or you know an event occured like you have steam or coolant smell.. where you arent going to be able to cool it down.. otherwise.. idling drops these things pretty quickly..



Viscous fan clutches are notorious for going bad.. and the split radiator / turbo cooler sometimes makes the fans come on a little late anyway... but if it working you'll hear it.... it slowly speeds up to a bit of a roar.. then slowly speeds down as the engine heats and cools..
-Christopher
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Old 06-27-2019, 04:11 PM   #7
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Quote:
Originally Posted by cadillackid View Post
if you are reaching 220-225 and like the last post, not hearing the fan roar then I would be checking the fan clutch... spiking it to 220-225 wont hurt it.. if the alarm starts ringing... (it will be a beep-----beep-----beep--) about ever second and the oil/water (red light) will be lit.. then you need to think about cooling it down..

if you are hauling pretty good.. reduce power and RPMs and it should go away in aminute or so.. you really want to avoid shutting it down unless it continues to spike or you know an event occured like you have steam or coolant smell.. where you arent going to be able to cool it down.. otherwise.. idling drops these things pretty quickly..



Viscous fan clutches are notorious for going bad.. and the split radiator / turbo cooler sometimes makes the fans come on a little late anyway... but if it working you'll hear it.... it slowly speeds up to a bit of a roar.. then slowly speeds down as the engine heats and cools..
-Christopher
Yes, forgot to mention that. Aside from the fan kicking in audibly at low rpm you want to hear it cycle when pushing the bus hard on the flat highway like Christopher described. I pretty much keep my all-day-long cruise speed just below where the cycling starts.

Changing to the synthetic fluid made the truck go faster before the fan starts cycling. Slip in the torque converter and heat generated depends on the viscosity of the fluid. The synthetic fluids do not get as thin when they get hot so the negative feedback effect (low viscosity causes higher temperature which causes lower viscosity...) in the system is less dramatic.
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Old 06-28-2019, 08:35 AM   #8
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my coolant and trans oil temps are about that same too. it got real hot one time going up the grapevine but never heard an alarm or spit any fluid. it was like 230 or a little more i think hard to remember now.
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Old 07-12-2019, 02:48 PM   #9
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Quote:
Originally Posted by alpine44 View Post
Yes, forgot to mention that. Aside from the fan kicking in audibly at low rpm you want to hear it cycle when pushing the bus hard on the flat highway like Christopher described. I pretty much keep my all-day-long cruise speed just below where the cycling starts.

Changing to the synthetic fluid made the truck go faster before the fan starts cycling. Slip in the torque converter and heat generated depends on the viscosity of the fluid. The synthetic fluids do not get as thin when they get hot so the negative feedback effect (low viscosity causes higher temperature which causes lower viscosity...) in the system is less dramatic.


What synthetic fluid do you use? I was trying to find an amsoil product but couldnít figure out which one if any would work.
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Old 07-12-2019, 06:20 PM   #10
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Quote:
Originally Posted by cadillackid View Post
those temps are about what I ran with an AT545... the computer rings the alarm bells for coolant and oil between 228-235 depending on which setting it has.. thats the "im too hot do something NOW" warning... oil temps usually run 10-15 degrees above coolant temp if you are spinning high RPMs..



your transmission really likes to be cooler than 220 with standard fluid.. if your engine coolant is already at 210-220 its going tp be hard for the trans to cool off into its comfort zone of 180-200 unless you install an external trans cooler..



that said, i was driving a 40 year old bus across the country last year in the cascades.. my engine didnt put out much power as I just figured.. its an older gasser.. my AT540 was around 200-220.. as i got higher and higher I never thoguht about it but seemed like it was running nicely.. yeah turns out the bus lived its life above 5000 feet so the carb was tuned for it.. at one point I was climbing from 6000 to near 9000 feet... i had it buried, haulin arse... then I smelled trans fluid.. I stopped (my engine temp was a nice 210).. trans fluid was everywhere.. the ground.. the exhaust.. smnoke everywhere.. I hit the trans with the temp gun and I was at like 385.... I let it cool down for an hour and a half.. added a gallon of fluid and finished the next 2300 miles without a hitch (albeit lighter on the pedal)...


so yes overheating a trans can destroy it.. but they also tend to be somewhat more durable than people might suggest at times..



take it easy on it. downshift.. running higher RPMs at lower speed allows the fan clutch on the engine to engage and really spin, as well it also puts less stall load on the unlocked torque converter..

a buried pedal with the RPMs spiking and the bus going slow and in a higher gear tends to heat things up faster ....
That reminds me of the 392 and allison that was in my bus, always hot and fluid everywhere. Sooo glad I took that out, and put a 345 and manual trans in. I can stand on it all day and never see the temp go up at all, even pulling trailers in the mountains. I am hoping yours was a one time only thing.
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