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How long to reach ATX operating temp? Opposite of slipping?

318 Views 4 Replies 3 Participants Last post by  paul93VR4
Especially compared to my previous Infinitis that would warm up in 3-4 miles, this feels like it takes a long time.
On average, it's about 7 miles or 10 minutes for my trans to reach operating temp. It will finally go into TC lock-up above something like 140F. I'm in Florida and it's 75 in the mornings. During the winter, it takes about 10 miles or 15 minutes.
My car has the shared cooling with the radiator:

I would think it should warm up a bit faster since my engine is at full operating temp in barely 1-2 minutes of leaving the house at a cruising speed around 50. The radiator is original and is quite calcified inside, but coolant temps never exceed 196. Most of the time it's right around 190.

I mentioned this in maybe one of my misfire threads, but the trans also 'slips' but in the opposite direction.
Normal transmission is 1>2>3>O/D > 500RPM slip down into TC lockup
Mine will rarely go 1>2>3>slip down 300RPM moderate rough shift>O/D >small slip down into TC lockup. It only does this when warm.

I can probably catch a video of it. To prevent it, I just lay into 3rd gear a little harder and it doesn't do it. It's only under something like 20% grandma throttle.

It's not the TPS because that's been replaced and calibrated.

With these 2 symptoms together, should I be checking fluid pressures? It makes me think 3rd gear has a bad seal or the little steel check ball in the valve body plate is allowing a pressure drop.
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I can’t answer your primary question, but will mention that after the engine reaches its operating temperature the thermostat starts to open. It does take a bit longer for the radiator to also reach the engine temp, so longer for it to do any heating to the trans fluid.

I did run a Prestone radiator flush sequence on mine recently- refill with water and the cleaner, then run it for 300 miles or so over a few days. Then I flushed it about five times, and refilled with new mix.
I ended up with about 8 gallons of antifreeze mix to take to the transfer station.

Unfortunately it’s tough to see inside the radiator- I didn’t want to pop off the hose to look, in case something leaked or broke.
Not sure where your going with this....

How are you measuring transmission temp. Lets just say there is a sensor in the pan and it warms up slow as your saying.

The engine is creating heat from the combustion process. Horribly inefficient the internal combustion engine is....

Now lets go back to how heat is created in the transmission. Through work, it creates heat from slippage of the clutches/bands and the forces of the actual transmission of power and the shear of oil in the TC.

creates is a poor word choice. The heat isn't created. Its the change of energy from one form to another....

Also the oil is heated going through the cooler in the radiator if that fluid ( engine coolant ) is warmer than the transmission oil.

Point being, if the transmission isn't overheating move on.

You said radiator is calicified. OK lets go there.
More difficult for the transfer of heat to occur from radiator ( coolant ) to transmission oil because of the insulator, that being the minerals on the heat exchanger. So the transmission oil doesnt warm up as quick. Transmission doesnt have any problems so it isn't creating excessive amount of heat and it is conducting that heat away through the body of the transmission faster than it is creating it. Meaning more BTU heat is able to be conducted away than generated until a some point the amount of heat generated from work, slippage etc is greater than able to be removed from the heat exchanger and and exterior surfaces of the transmission.

Again, move on.

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Sorry to take a while to get back to this and thanks for the explanation of the slowed exchange of heat in the radiator due to calcification.
Part 1: Temps and time to warm up
The concern was that since it is not reaching operating temp to go into torque converter lock-up (apparently around 125-130F), the trans stays in its 'slip' state for longer, wearing the clutch packs instead of the TC locking up and directly matching the engine RPM.

Part 2:
Here's the video I recorded a few days ago. I am accelerating with a very steady ~25% throttle.

You can see the very slight 100RPM hesitation at 3,000 RPM as it shifts 2-3. After 1-2 seconds operating normally in 3rd, it pulls down about 200-300RPM as my speed it still increasing through 3rd. It lingers at 2,500 for 1-2 seconds as speed is still slowly increasing and then thuds down into 4th.
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Your looking at this a bit incorrectly and comparing it to another completely different vehicle. If you haven't seen a couple other of that exact model with the same TCU calibration you don't really have anything to compare it to.

It isn't wearing the clutch packs just because it isnt shifting into TCL. For many years no car had a locking converter. Clutches & bands wear only during the actual shift change, when they apply and release there is slip. At all other times they are together as one. Steel to fibre to steel. Edited for grammer: No different than a manual transmission clutch. The locking converter is there for one reason. Fuel economy. A non lockup converter doesn't wear anything, it just slips in the small gap between the input and output components of the converter since at this point there isn't a mechanical connection.

In your video you start off at a higher throttle opening and it appears you let off after about 40 so its a bit unrealistic to compare one gear shift to another. TCL is determined by the particular calibration of the TCU. You cant know what bad is unless you know what good is....Really all you should care about is does it shift cleanly, meaning no stutter or flares gear to gear.

Saying that, It ( the transmission ) has miles on it...meaning wear... the original fluid is NLA. Yes I know there is a replacement but are the frictional characteristics & viscosity EXACTLY the same as when it was designed and built? Doubtful. Any fluid you pick today will have a different additive package and all will shift a bit different from another,

If you really want to continue to explore this subject which IMO is a waste of time....

As far as shifting goes IIRC you had added some additive to the transmission. Kind of hard to make any determination on shift characteristics with that in there. Only way to see how it shifts and make any judgments is to have clean fluid, clean filter and that means dropping the pan and flushing all the old fluid out....

Are you sure of the proper TC lockup temperature? If you have a quality IR thermometer you could start driving and when it goes into TCL get under the car and check the pan temperature. You got to be close to and not some oblique angle to be even half ass accurate....looking for the highest temp on the pan. Checking this a few times over various days to see if it is consistent. AND if it is then does it match what the TCU thinks is the actual temperature ? maybe the TCU thinks the temperature is lower than it really is.

Just because your engine is at operating temp doesn't mean the radiator is completely at that temp as you start out... that lower part of the radiator may be comparatively cool as the thermostat is staying more or less closed keeping the engine at temp until you really get the transmission isn't picking up much heat from the radiator to warm itself up. Hot goes towards cold so if the bottom of the radiator is cooler than the transmission, heat will go out of the transmission until at some point they find a equilibrium

Well I am totally out of breath with this.... nothing further to add and I don't see it for me at least being a topic to discuss further with no indication of a problem.

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