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Discussion Starter #1
This topic was beaten to death, but I can't find an answer to my question ... so here it goes:

1) bypass - easy to do, SMOD-free
2) heat is an issue after bypass - install fan, switch, temperature sensor

3) cold is an issue - now what:

Question is, how much can bypass affect the vehicle in really cold climates ? Right now, without bypass, when I plug in the block heater at -30, -40 deg. C. the transmission gets some heat. With bypass I'll be looking into running with dead cold transmission. Can that affect the life span of the transmission ?
 

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Just take it easy on the truck for the first few minutes and you should be good. To help a little after the bypass I installed my secondary cooler behind the stock one so that it would get some engine heat when im not moving (morning warm up). I have a superchip cortex not a bullydog tuner however so I cant measure the trans temp to be certain there is any benefit.
 

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3) cold is an issue - now what:
Can you elaborate on this point? I think you may be referring to some of the initial speculation that the in-radiator trans cooler actually provided some heating to the transmission fluid as the motor is warming ... jeffredx's temperature testing has shown that this is just not the case. Rather, the transmission will heat faster than the engine coolant, and heat transfer will always be from the transmission to the coolant through that cooler.
 

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Can you elaborate on this point? I think you may be referring to some of the initial speculation that the in-radiator trans cooler actually provided some heating to the transmission fluid as the motor is warming ... jeffredx's temperature testing has shown that this is just not the case. Rather, the transmission will heat faster than the engine coolant, and heat transfer will always be from the transmission to the coolant through that cooler.
I was going to state this as well. Jeff has proven this atleast twice that I know of now with data to prove the results. The hesitation I had though, was that Jeff did this in warmer climates (I think?) and I wasn't sure if in a much colder climate (like the OP will see in BC) if that data would still be true?
Again, this was simply an idea...at best...I don't have anything to suggest that I would be right in this scenario, although I'm sure that either skibum or Jeff could elaborate very easily. I have a feeling I'm wrong on this, but I don't know all that much about heat transfer so I figured I'd throw it out there.
 

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Your transmission will warm up faster than the coolant in the radiator. There is no circulation through the radiator until the thermostat opens up, and those of us who live in cold climate areas know that takes a while. If you are that nervous about it just let the truck idle in neutral for a few minutes before you drive.
 

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Discussion Starter #6 (Edited)
Can you elaborate on this point? I think you may be referring to some of the initial speculation that the in-radiator trans cooler actually provided some heating to the transmission fluid as the motor is warming ... jeffredx's temperature testing has shown that this is just not the case. Rather, the transmission will heat faster than the engine coolant, and heat transfer will always be from the transmission to the coolant through that cooler.
to my best knowledge the block heater heats the coolant up and transfers the heat onto to transmission fluid as well ... I am not talking warming up while running the car, I am talking about the car being plugged in overnight

I have no proof for that though, but I noticed that the nights when I don't plug it in (thinking it won't get too cold, or simply forget to do it), the vehicle shifts much harder in the morning for first 5-10 kilometres

I do understand that it is just an anecdotal evidence, but you definitely can feel it (overnight temperatures -20 or less)

Your transmission will warm up faster than the coolant in the radiator. There is no circulation through the radiator until the thermostat opens up, and those of us who live in cold climate areas know that takes a while. If you are that nervous about it just let the truck idle in neutral for a few minutes before you drive.
I always leave the car to idle in the really cold mornings, but my experience is the same ... if not plugged in overnight, it does shift harder

and it supports Jeff findings, that running the engine won't warm up transmission ... the question is, does block heater do it ? and do I loose this doing bypass and what consequences there are
 

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Is the only symptom that you're seeing, the hard shifting? I'm an MT guy and I don't really know ATs *that* well, so I can't really say if that's a bad thing (aside from NVH concerns) ... I suppose you could do a bit of research into extended use of ATs with higher viscosity fluids - the cold increases the oil's viscosity, and see if there's anything conclusive out there that would lead you to alter what you're already doing. But I think barring that (or other info that I don't have) the long and short of it, is: take it easy if you feel like it needs to warm up, and other than that don't worry too much.

To your questions, though, I *think* you should be at least getting some conductive heating into the trans from the block heater (aside: I'm not all that familiar with block heaters, they're primarily a simple resistive element that goes in through one of the freeze plugs, right?) - and I think your observation about smoother shifting on mornings when you've used it supports this. I don't see how adding the in-rad cooler bypass would greatly reduce that, because with the block heater there's not going to be any fluid-fluid convective transfer at that cooler (no fluid flow without the water pump or trans fluid pump active, unless the block heater includes its own pump) ... only conductive transfer, and the conductive path along the fluid lines to/from the in-rad cooler isn't going to be very strong (if at all). My strong assumption is that the primary trans heating due to the block heater, is going to pass through the bell housing and flywheel/torque converter; and as long as the trans temp isn't getting to where you're cooking the fluid (like 205-235* or something, right?) you'll be fine on the hot end too ... and I'd be willing to bet you're not getting a 250* differential with a block heater.

But, if you want to understand it 100%, then check out Jeff's thermocouple set-up, and be prepared to try a few different configurations ... ;)
 

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skibum315's description is spot on. Heat will transfer from the aluminum block to the aluminum trans case.

Ambient temperature will not affect the heat flow of the from the ATF to the coolant in the radiator. If you do add an aftermarket ATF cooler it may actually slow do the heating of the ATF. Most aftermarket cooler flow coolant at all ATF temperatures while the factory air:ATF cooler has a thermostatic valve that bypasses the ATF flow when the ATF temperature is below about 130F.

If you do want to heat up the ATF before driving during subzero temperatures you can heat up the trans by putting the trans in Drive, firmly applying the brakes, and gently accelerate the engine to 1200-1500 rpm. Doing this for a few minutes will heat the trans. Use caution if you choose to do this, DO NOT run the engine rpm beyond 1500 or run the engine at the higher rpm for more than a few minutes.

Cheers,
Jeff
 

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Discussion Starter #9
thanks for all the explanation :)

I will throw Bullydog into XTerra to see how temperatures are once it gets cold enough here, unless we can figure out what PID and equation is required for Torque Pro by that time :study:
 

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With your block heater plugged in your transmission will warm up faster as the thermostat will open up sooner due to the coolant and engine block already being warm. How much faster depends on how warm your heater gets the coolant. You would then be exposing cold atf to warm coolant when it circulates through the radiator.
 

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With your block heater plugged in your transmission will warm up faster as the thermostat will open up sooner due to the coolant and engine block already being warm. How much faster depends on how warm your heater gets the coolant. You would then be exposing cold atf to warm coolant when it circulates through the radiator.
The ATF is not heated when it passes through the heat exchanger in the radiator. In -20F (or C) temperatures the thermostat will not open much if at all in easy driving. The transmission will heat up from internal heat generated in the torque converter and gears.

Cheers,
Jeff
 

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Tap into your block heater with a simple heater setup strapped to trans pan.

Essentially... do an aftermarket home made block heater setup on your trans pan. Dirt cheap and takes the guessing out of the equation.

All the data in the world sounds good when the tests were performed in different climates but realistically -20 to -40 is nasty and mechanical parts just don't like it.

Best advice i can offer...... MOVE :)
 

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I agree with the above post. - simple oil pad heater like Volverine should do the trick if extreme cold is in your immediate future after the bypass. This will give you smoothe shifting for first few minutes if your morning drive.
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so im back from the dead and deployed. my thread on bypassing and adding a second cooler has been around for a few years. the x has handled two winters in Minot north dakota. in LOTS AND LOTS of SUB ZERO DAYS (im talking -10 and colder) i have not had a SINGLE issue or slip or hard shift. thats with 100,000 hard off roading miles and "warming" the truck up for 5 mins before driving. i have no block heaters or fluid heaters of any kind and i park outside. come on guys put this topic to bed. use a high quality trans fluid, do the bypass and stop thinking about it.
 

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so im back from the dead and deployed. my thread on bypassing and adding a second cooler has been around for a few years. the x has handled two winters in Minot north dakota. in LOTS AND LOTS of SUB ZERO DAYS (im talking -10 and colder) i have not had a SINGLE issue or slip or hard shift. thats with 100,000 hard off roading miles and "warming" the truck up for 5 mins before driving. i have no block heaters or fluid heaters of any kind and i park outside. come on guys put this topic to bed. use a high quality trans fluid, do the bypass and stop thinking about it.
I like the way you think ...
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