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Old 08-31-2015, 08:52 AM   #1
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Transmission temps

Just returned from a trip, first time in any mountains. Bus did well except trans temps seemed a bit high. A lot of 250 with some 280, the 280 when out of lock up I think. This makes sense to me, any thoughts?

I already have a fluid/water cooler. This makes a lot of sense to me.
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I recently advised a guy his truck and RV needed more fluid capacity. He was gonna buy or make a deep trans pan. Too much money. An old air brake tank was gotten from a big rig truck. Some brackets were made and tank installed with some additional fluid lines. The increased capacity of about 3 gallons allowed the fan cooled cooler to keep the fluid at about 185 degrees while climbing up our 12,000 ft mountains with a full payload. Don't ya love it when a plan works? Frank
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Tank is in series with 1/2 inch cooler line. About 3 gallons of surplus allows for a really long hill with a tremendous load. And the challenge is kool. Frankj
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Old 08-31-2015, 10:48 AM   #2
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That seems like a solid and simple plan to me. The tank will help to level out the temperature spikes. If you were always running hot then I wouldn't expect it to do much, but since you only overheat when climbing hills it should do just fine.
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Old 08-31-2015, 11:03 AM   #3
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seems logical, I need to look at doing that (is 1/2 inch big enough?)
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Old 08-31-2015, 02:43 PM   #4
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is 1/2 inch big enough
That seemed a bit small to me, did some research and from the Hayden catalog the recommended cooler for the 643 has 3/4 FPT, The recommended cooler is a 1299 which is a 2 pass oil cooler with a cooling btu/hour capacity of 36,500 61,000. A 1290 is just a tad smaller with same size fittings and a better flow rate with capacity of 42,200 66,400
I'm now thinking I might go this route and mount it in front of the side mounted radiator. The fan pulls from the outside so I wouldn't need any kind of aux fan for the cooler. If I change to Trynsend fluid those extra 3 gallons I wouldn't have to buy would almost pay for the cooler.
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Old 08-31-2015, 02:48 PM   #5
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I cant understand how you get those temps. I hardly see mine at 180.
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Old 08-31-2015, 03:17 PM   #6
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Originally Posted by opus View Post
I cant understand how you get those temps. I hardly see mine at 180.
I can't either it can't be because I was climbing higher mountains than you. I never paid that much attention before, but I was pulling something heavier this time and was watching. It seems like before the gauge was straight up, or roughly 200. Thought I'd change to Trynsend before making the real decisions.
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Old 08-31-2015, 03:26 PM   #7
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now this question?

where are you reading the temperature?

my gage reads converter out so it is always hotter than the reading after the radiator/heat exchanger
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Old 08-31-2015, 03:32 PM   #8
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Might take into consideration where your temp sending using is too. Mine is in the pan. I forget where is the most accurate place to have it.
You have a pan filter and a spin on [that might be a retarder setup thing]...right?

Was it hunting gears, did you manually drop it? Did you aggressively climb the hill or just meander up it? I'll drop mine to 3rd and sit it about 2000 RPM. It will climb anything at that speed. I pretty much have the throttle backed to about 1/4 throttle to keep from going above that RPM. I figure no sense having things wound tight just to fight to go up hill fast. Especially with a 5 mile grade or so.

Just thinking out loud.....
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Old 08-31-2015, 04:56 PM   #9
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A Ford diesel forum I go to has a retired Ford Tranny engineer that answers alot of post about the junk E4OD transmission. Something he posted "trans are tested + built to run at 220* all the time."
Luckily mine stays at 180 most of the time. I have noticed that outside temp has a fair amount of effect on the trans temp.
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Old 08-31-2015, 11:26 PM   #10
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Sorry I didn't respond to your PM. I have been moving the last few days.

I would be more in favor of a large flat plate cooler mounted under the bus. It will provide the extra capacity, and help cool the fluid inside. You could even mount a fan on it under your bus.

They also make oil thermostats that allow your trans to warm up via the water to oil heat exchanger, then when it gets to hot, the thermostat opens the port leading to the cooler. This prevents over cooling the trans in cold weather, but still cools well.

If you live in a warm climate, I would bypass the water to oil exchanger in favor of a dedicated trans cooler. IMO the use of the water to oil exchanger is highly inefficient and puts more load on your engines cooling system.

Nat
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Old 09-01-2015, 08:29 AM   #11
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Thanks for all your responses.

Quote:
Might take into consideration where your temp sending using is too. Mine is in the pan. I forget where is the most accurate place to have it.
You have a pan filter and a spin on [that might be a retarder setup thing]...right?
My temp is taken right out of the converter which explains temp variations. I have an external filter and fluid/water cooler. I plan on putting a sender in the pan, that would tell how well the cooler is working.

Quote:
Was it hunting gears, did you manually drop it? Did you aggressively climb the hill or just meander up it? I'll drop mine to 3rd and sit it about 2000 RPM. It will climb anything at that speed. I pretty much have the throttle backed to about 1/4 throttle to keep from going above that RPM. I figure no sense having things wound tight just to fight to go up hill fast. Especially with a 5 mile grade or so.
I may have been driving too aggressively, I drove a truck for 20 years, but it was std transmission and had the horsepower to pretty much climb anything at speed. Really high temps were seen when starting up hill and never got to 3rd, so no lockup.

sdwarf36,
That lead me to more research and I found this (taken from various forums and condensed)

Quote:
Tom Johnson and I was the Transmission Fluids Engineer at Allison Transmission from 1990 until my retirement in 2009.

Don't worry about temperatures on TranSYnd. I've run it in the lab at 325F for 600 hours straight with not much change except for some oxidation. When I say the Allison will run all day long at 250F, I mean it. This temperature will do absolutely nothing to the transmission. Internal parts are designed to run at up to 350F.

Of course, running cooler is always better but the kinds of temps you all are seeing is not much. If you don't believe me, take oil samples and you'll see that temperatures up to 250F will do nothing to TranSynd or the transmission. So ...... stop worrying about it and move on to something else.


I would be concerned if you ran over 225F consistently. Really you should normally operate somewhere around 180-200F. Maybe even lower. The Allison is designed to take much higher temperatures but the fluid will degrade at a faster rate. General rule of thumb is that fluid life is cut in half every time you increase the temperature by 18 degrees Fahrenheit (10 degrees Centigrade or Celcius). Keep in mind that this general rule is based on chemical reaction times and TranSynd can take much higher temperatures for much longer periods of time
I think my first order of business is going to be change to synthetic fluid and install sender to oil pan, also change my driving habits. From what I have gotten from all of this is, if I change to transynd or equivalent, the higher temp right out of the converter isn't really that big a deal as long as it doesn't go high in the pan, and may not be at all unusual.
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Old 09-01-2015, 09:53 AM   #12
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TranSynd will deal with heat much better than the older Dexrons and such. But only to a point. Allison put out a chart a while back (I'm still trying to relocate) that spells out the expected fluid life based on running temps. Even the new gen fluids life gets dramatically reduced when run at temps above about 220. And even fairly short exposure to higher temps (like 250-280) can render it bad enough to call for replacement in pretty short order.

Effective transmission fluid cooling is critical to maintaining the trannies health as well as the fluids.
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Old 09-01-2015, 07:23 PM   #13
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Originally Posted by somewhereinusa View Post
I may have been driving too aggressively, I drove a truck for 20 years, but it was std transmission and had the horsepower to pretty much climb anything at speed. Really high temps were seen when starting up hill and never got to 3rd, so no lockup.
If you werent in lockup, that would have been a good part of your problem. Non-lockup is just a means to get to the next lockup without such a big jump.
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