Economics of auto transmission maintenence

[Linctex]

Originally Posted By: HangFire
If installing an aftermarket ATF cooler, but it in the loop BEFORE the radiator pass-through, so the radiator can warm-up overcooled fluid. That's the reason it passes through the radiator in the first place- not just to cool down hot ATF, but to warm-up cold ATF.


This actually a myth.

I saw a post a couple months ago by a thermodynamics engineer (I think at Ford?) and on a test stand with like 43 thermocouples in every location imaginable, he said the hot coolant NEVER "added heat" to the transmission fluid.... ever.

 

[Brad_C]

Originally Posted By: slacktide_bitog
Most cars never get their transmission fluid changed and go to the junkyard with their original factory fill ATF! Transmission shops say most of the problems they see could've been easily be prevented with fluid changes.


We looked at a vehicle recently with the notorious ZF 6 speed auto. Talking to the mechanics, they said the description of the "lifetime fluid" was pretty accurate, it's just the lifetime is a lot longer if you change it every 70,000km.

 

[WobblyElvis]

Originally Posted By: Linctex
Originally Posted By: HangFire
If installing an aftermarket ATF cooler, but it in the loop BEFORE the radiator pass-through, so the radiator can warm-up overcooled fluid. That's the reason it passes through the radiator in the first place- not just to cool down hot ATF, but to warm-up cold ATF.


This actually a myth.

I saw a post a couple months ago by a thermodynamics engineer (I think at Ford?) and on a test stand with like 43 thermocouples in every location imaginable, he said the hot coolant NEVER "added heat" to the transmission fluid.... ever.


I don't know about a myth.
I had a 79 Chev Malibu and the heater hoses not only went to the heater core but they also ran to the top and bottom of one of the rad tanks. It was a cross flow radiator and the tank that had a transmission cooler in it, also accepted these heater hoses. Before the thermostat opened warm coolant would flow across the transmission cooler. I can't think of any other reason for this arrangement.

 

[thescreensavers]

Originally Posted By: Linctex
Originally Posted By: HangFire
If installing an aftermarket ATF cooler, but it in the loop BEFORE the radiator pass-through, so the radiator can warm-up overcooled fluid. That's the reason it passes through the radiator in the first place- not just to cool down hot ATF, but to warm-up cold ATF.


This actually a myth.

I saw a post a couple months ago by a thermodynamics engineer (I think at Ford?) and on a test stand with like 43 thermocouples in every location imaginable, he said the hot coolant NEVER "added heat" to the transmission fluid.... ever.


it's simple physics if you take two bodies of fluid at different temperatures they will want to equalize basic thermodynamics 101, it's how radiators work, if coolant is at 190F and ATF is anything below that then guess what ATF is going to warm up don't need even a single thermocouples for that, Also this is how oil warmers work too by using hot coolant with "cold oil".



Most modern transmissions have thermostats in the cooler line circuit.

Cooler lines are usually a bypass system's so not all fluid goes through them only a %. So a cooler line going through a radiator may warm up fluid but total amount of fluid in the transmission may not warm up much. Maybe this is what the engineer was touching on.

B&M and similar stacked plate coolers have internal bypass when fluid is too cool, I have one on my XJ and it works quite well.

 

[HangFire]

Originally Posted By: Linctex
Originally Posted By: HangFire
If installing an aftermarket ATF cooler, but it in the loop BEFORE the radiator pass-through, so the radiator can warm-up overcooled fluid. That's the reason it passes through the radiator in the first place- not just to cool down hot ATF, but to warm-up cold ATF.


This actually a myth.

I saw a post a couple months ago by a thermodynamics engineer (I think at Ford?) and on a test stand with like 43 thermocouples in every location imaginable, he said the hot coolant NEVER "added heat" to the transmission fluid.... ever.


I'd like to see/hear/read that. Because I know Ford well (and some of their former engineers), and they would drop useless feature in a New York Minute to save a few cents.

Perhaps what he was trying to say was that a hot radiator can't overheat a transmission.

 

[Linctex]

Originally Posted By: HangFire

I'd like to see/hear/read that. Because I know Ford well (and some of their former engineers), and they would drop useless feature in a New York Minute to save a few cents.


I'll try to find it again. I think it was on a F150 or Mustang forum.

He CLEARLY said the transmission fluid does not get heated by radiator coolant. Period.

 

[Brad_C]

Originally Posted By: HangFire
Originally Posted By: Linctex
Originally Posted By: HangFire
If installing an aftermarket ATF cooler, but it in the loop BEFORE the radiator pass-through, so the radiator can warm-up overcooled fluid. That's the reason it passes through the radiator in the first place- not just to cool down hot ATF, but to warm-up cold ATF.


This actually a myth.

I saw a post a couple months ago by a thermodynamics engineer (I think at Ford?) and on a test stand with like 43 thermocouples in every location imaginable, he said the hot coolant NEVER "added heat" to the transmission fluid.... ever.


I'd like to see/hear/read that. Because I know Ford well (and some of their former engineers), and they would drop useless feature in a New York Minute to save a few cents.

Perhaps what he was trying to say was that a hot radiator can't overheat a transmission.


What he was saying is that the cooler is in the cold side of the radiator, and in pretty much every observable case the coolant in the radiator is colder than the transmission fluid it's supposed to be "warming". When the thermostat is closed, the radiator is cold. When the thermostat is open, the *hot* side of the radiator is at or about thermostat temperature, but as the radiator does what it does and rejects heat into the airflow, the liquid on the *cold* side is significanty cooler. By that time, the fluid exiting the torque converter is already hotter than the cold-side coolant.

It would be worth finding the thread if for no other reason that to see a bunch of unmentionables repeatedly try to argue "logic" against someone with experience and real evidence.

 

[Shannow]

The example is specifically a cooler IN ADDITION to the cooler in the radiator tank, e.g. an air cooled finned type.

The advice when I was messing around in the '80s was to always install this so that the hot oil goes through the air cooled cooler first, then the tank cooler. If the tranny is extremely hot, then the cold tank cooler doesn't work as hard. If the tranny is cold, then the cold tank cooler keeps the return ATF at a reasonable temperature if the air cooled cooler drops the temperature too much.

My Caprice has a factory cooler by Holden which is after the cold tank cooler.

I get the logic of the former, but nearly always observe the latter.

 

[4WD]

As does my Tru Cool LPD (low pressure drop) - run between factory cooler and spin on filter.
With an add on drain plug - can do pan volume and a real filter in 20 minutes ...

 

[Lolvoguy]

...and here I was getting strange looks from the auto parts store folk for wanting a trans fluid HEATER.

thanks for clearing that up guys!

 

[meborder]

Originally Posted By: Linctex
Originally Posted By: HangFire

I'd like to see/hear/read that. Because I know Ford well (and some of their former engineers), and they would drop useless feature in a New York Minute to save a few cents.


I'll try to find it again. I think it was on a F150 or Mustang forum.

He CLEARLY said the transmission fluid does not get heated by radiator coolant. Period.


here's a good one from Powerstrokearmy.com where he is responding to a slew of questions poised at him from another user:

Quote:
Mark Kovalsky08-23-2016, 09:53 AM
so if thats the case what truck was this done on a 6.0?
Yes, I did this on a 6.0L as well as many other vehicles. It was my job at Ford to do this.

what was the air temp?
I've tested in air temps from as cold as -40°F to as hot as +121°F

was the truck warm?
Depending on the test the truck started cold, or it started hot. I've done it both ways.

was that while driving or idling?
I've tested idling, city cycle driving, highway driving, and anything in between.

what was the coolant temp?
Depending on the test coolant temps were anywhere from -40°F to just below boilover.

theres alot of variables in this and you might of checked but how did you check it what tool did you use to check these temps?
That's why every test had hundreds of thermocouples to measure everything going on. I had thermocouples inside the radiator around the trans cooler. I had thermocouples measuring the ATF temp in and out of the radiator cooler and the air to oil cooler. I also measured air temperature in and out of the radiator, around the engine, and around the transmission.

i dont understand how what your saying would work the way you say it dose and im just trying to understand what you had going on because id be interested in seeing this for myself interesting concept
Before I started measuring this I didn't think this was how it worked, either. I was surprised that the radiator never warmed the trans fluid, but it does not. I have measured this on many different types of vehicles in many, many different conditions.

The only time it is even close is at startup when the coolant and the ATF are at the same temperature. Once the engine starts the ATF starts to flow. It warms slowly, but the coolant around the radiator trans cooler doesn't warm at all, because the thermostat is closed. When the thermostat finally opens it dumps 200°F (more or less) coolant into the radiator. It doesn't stay open for long because the engine sucks ambient temp coolant in through the lower hose, causing the thermostat to close quickly. By the time this hot coolant gets the transmission radiator cooler it's back to near ambient. Remember, I had thermocouples in the radiator to measure this, I'm not guessing.

If you want to see actual data you'll have to go to Ford. I didn't own that data and I only took my memory of it when I left Ford.

 

[meborder]

as to the economics of transmission maintenance:

I just paid about $200 to have the fluid on my transmission replaced.
with the cost of a replacement transmission being well over $2000, one could replace the fluid more than 10 times and still come out ahead.

so, at the extreme, if you replaced it ever 20,000 miles, you have spent $2,000 at 200,000 miles.

so even if you do it at a ridiculously low 40,000 miles each time, in 200,000 miles you have not even come close to the cost of new transmission.

I've done mine twice now ... so I've spent $400 to avoid spending over $2,000.... that seems like pretty cheap insurance.

now, you may still have a failure. but, personally, I've never had a transmission that I've maintained go out under 200,000 miles. I've never had one go out at all under my watch, but I generally stop driving them around the 200k mark.

 

[SirTanon]

Originally Posted By: meborder
as to the economics of transmission maintenance:

I just paid about $200 to have the fluid on my transmission replaced.
with the cost of a replacement transmission being well over $2000, one could replace the fluid more than 10 times and still come out ahead.

so, at the extreme, if you replaced it ever 20,000 miles, you have spent $2,000 at 200,000 miles.

so even if you do it at a ridiculously low 40,000 miles each time, in 200,000 miles you have not even come close to the cost of new transmission.

I've done mine twice now ... so I've spent $400 to avoid spending over $2,000.... that seems like pretty cheap insurance.

now, you may still have a failure. but, personally, I've never had a transmission that I've maintained go out under 200,000 miles. I've never had one go out at all under my watch, but I generally stop driving them around the 200k mark.



... and this is paying someone else to do the work for you.

I do my own trans fluid drain & fill, every 30,000 miles. This means all I'm paying is the price of ~4 quarts of trans fluid. The last two changes were done using Valvoline MaxLife LV ATF, meaning I paid less than $20, and spent less than 30 minutes, to do a drain & fill. Even paying for 4 quarts of genuine MC Mercon LV, I'm only paying about $26 at the local dealership.

Assuming the trans only would cost $2000 to replace, then I could do between 80 and 100 drain & fills before it would cost the same as a new trans.

In reality though, let's say I'll own the car for another 240,000 miles - That means another 8 drain & fills @ a total cost of only about $200. IMHO, this is a no-brainer. Of COURSE I'm going to do the fluid changes.

 

[meborder]

Originally Posted By: SirTanon
Originally Posted By: meborder
as to the economics of transmission maintenance:

I just paid about $200 to have the fluid on my transmission replaced.
with the cost of a replacement transmission being well over $2000, one could replace the fluid more than 10 times and still come out ahead.

so, at the extreme, if you replaced it ever 20,000 miles, you have spent $2,000 at 200,000 miles.

so even if you do it at a ridiculously low 40,000 miles each time, in 200,000 miles you have not even come close to the cost of new transmission.

I've done mine twice now ... so I've spent $400 to avoid spending over $2,000.... that seems like pretty cheap insurance.

now, you may still have a failure. but, personally, I've never had a transmission that I've maintained go out under 200,000 miles. I've never had one go out at all under my watch, but I generally stop driving them around the 200k mark.



... and this is paying someone else to do the work for you.

I do my own trans fluid drain & fill, every 30,000 miles. This means all I'm paying is the price of ~4 quarts of trans fluid. The last two changes were done using Valvoline MaxLife LV ATF, meaning I paid less than $20, and spent less than 30 minutes, to do a drain & fill. Even paying for 4 quarts of genuine MC Mercon LV, I'm only paying about $26 at the local dealership.

Assuming the trans only would cost $2000 to replace, then I could do between 80 and 100 drain & fills before it would cost the same as a new trans.

In reality though, let's say I'll own the car for another 240,000 miles - That means another 8 drain & fills @ a total cost of only about $200. IMHO, this is a no-brainer. Of COURSE I'm going to do the fluid changes.


just in the interest of clarity, I paid $200 for a full fluid exchange. which in my case was 14qts + 2qts to burn plus $35 for the labor to do the work.

I generally do this every 60k-ish miles ... so twice-ish during my ownership (once when I buy it used, and once again 60k-ish miles later)

 

[Brad_C]

Originally Posted By: Shannow
The example is specifically a cooler IN ADDITION to the cooler in the radiator tank, e.g. an air cooled finned type.


That's right. And the theory was that you put the air-cooler *before* the in-tank unit to allow the in-tank unit to put some heat into cold fluid. The argument was that this never happens, so it doesn't really matter how you hook it up.
I put the air-cooler before the in-tank and put a bypass thermostat over the air-cooler to prevent it over-cooling. In reality I could have disconnected the in-tank unit completely becuase it never actually warms the fluid.

One interesting argument he made is on the efficiency of the in-tank units. Being a liquid to liquid cooler, it is far more efficient than a air-to liquid on a size basis. So those in-tank units have some serious cooling ability. Not necessarily enough to cope with a towing load, but certainly enough for day to day duty.

 

[Linctex]

Originally Posted By: meborder
here's a good one from Powerstrokearmy.com where he is responding to a slew of questions poised at him from another user:
Quote:
Mark Kovalsky 08-23-2016, 09:53 AM
That's why every test had hundreds of thermocouples to measure everything going on. I had thermocouples inside the radiator around the trans cooler. I had thermocouples measuring the ATF temp in and out of the radiator cooler and the air to oil cooler. I also measured air temperature in and out of the radiator, around the engine, and around the transmission.


That's fantastic, thanks for finding & posting it.

It sounds like the same guy, though from memory it sounds like a different vehicle.

Incidentally on my F-150 with the factory towing package, the finned air transmission cooler is mounted so fluid goes through the radiator cooler first, then through the air cooler. I don't have a temp gauge on the outlet of the finned cooler, but I have felt it with my hand and it is NEVER "hot" enough that I couldn't grab it and hold my hand there indefinitely. (less than 140*F ?)

This truck does have bypass thermostat in the trans cooler lines, about 6"-8" from the trans, and is supposed to by-pass unless cooler fluid is needed.

 

[meborder]

Originally Posted By: Linctex

That's fantastic, thanks for finding & posting it.

It sounds like the same guy, though from memory it sounds like a different vehicle.

Incidentally on my F-150 with the factory towing package, the finned air transmission cooler is mounted so fluid goes through the radiator cooler first, then through the air cooler. I don't have a temp gauge on the outlet of the finned cooler, but I have felt it with my hand and it is NEVER "hot" enough that I couldn't grab it and hold my hand there indefinitely. (less than 140*F ?)

This truck does have bypass thermostat in the trans cooler lines, about 6"-8" from the trans, and is supposed to by-pass unless cooler fluid is needed.



There are many posts on many forums where you can find him saying the same thing many times over. He is very clear when he writes that he has never found a condition where the radiator warms the transmission fluid. If You want to learn what he has to say just do a search on his name and you will find a TON of stuff he has posted.

As best as I can decipher, he worked for Ford as a transmission engineer when the 1999 super duty rolled out. Ford was trying to save a buck and the cooling department wanted to remove the oil-to-water cooler in the radiator. as a transmission engineer, he/they recommended against it, but was over-ruled and the super duty rolled out with an oil-to-air cooler only. The result of this was ford had to replace a ton of transmissions under warranty due to overheating. a year an a half later, mid 2000 model year, ford issued a TSB to have a new radiator with an integral oil-to-water cooler installed on vehicles which suffered from overheated transmission. From mid model year 2000 to current, they came off the line with both coolers.

as I understand the story, this honked him off enough that he moved over to the cooling department and was a major part of designing the transmission cooler for the 6.0 powered 5r110w. Anyone paying attention knows that the auxiliary cooler from a 6.0 is the best drop in cooler one can buy for a super duty truck. the thing is absolutely huge at 31 rows (redesigned to 28 rows later, with no loss in cooling), and uses 1/2" cooler lines.

Curious on your F-150:

What year is it and can you post a picture of the bypass you are talking about?
the 6r80 uses a thermostat, but it is internal to the transmission. They do make external thermostat/bypass units which can be added to a vehicle, but I'd caution their use. It has come up in conversations with Mark and his take was that they are good in theory, but in practice he has found them to be too restrictive and can actually compromise cooling.

With regard to the cooler arrangement, the oil-to-air cooler is always referred to as the Auxiliary cooler. which means the cooler in the radiator is the primary and does the majority of the cooling. According to him, plumbing the oil-to-water cooler first and the oil-to-air cooler will always result in the best cooling performance. I've never seen and OEM plumb them any other way and there is a reason. Coolers work off of temperature gradients and when you plumb the hottest fluid going into the most effective cooler first, you get better cooling than using the least effective cooler first.

 

[MolaKule]

It depends on the relative temperatures of each fluid and rate of temperature rise.

Scenario #1: Let's say engine is idling and allowed to warm up to operating temp. If transmission fluid is initially cold, thermal energy from the hot coolant will transfer to the transmission fluid, raising the ATF's temperature. Equilibrium will be reached some time afterwords.

Scenario #2: Immediate start and Drive-Off: Transmission fluid is initially cold, and engine coolant is cold. Most likely the tranny fluid will warm up first, thus transferring it's heat to the coolant, causing a temperature rise in the coolant. Later, engine coolant temp will rise AND IF engine coolant is hotter than the ATF, thermal energy will be transferred to the ATF, raising the ATF's temp. Equilibrium will be reached some time afterwords.

As an aside, notice all of the new 7 to 10-speed step shift transmissions have an internal circulating path such that the tranny fluid is allowed to warm up to operating temperature before the ATF is allowed to circulate through the external cooler.

https://www.grc.nasa.gov/www/k-12/airplane/heat.html

https://en.wikipedia.org/wiki/Convective_heat_transfer

 

[meborder]

The laws of thermodynamics still apply, nobody is arguing that.

The problem is that scenario #1 does not exist in nature, at least not outside of very extreme circumstances which will eventually result in an overheated engine.

The following from mr. Kovalsky explains pretty clearly what happens under normal operation:

Quote:
The only time it is even close is at startup when the coolant and the ATF are at the same temperature. Once the engine starts the ATF starts to flow. It warms slowly, but the coolant around the radiator trans cooler doesn't warm at all, because the thermostat is closed. When the thermostat finally opens it dumps 200°F (more or less) coolant into the radiator. It doesn't stay open for long because the engine sucks ambient temp coolant in through the lower hose, causing the thermostat to close quickly. By the time this hot coolant gets the transmission radiator cooler it's back to near ambient. Remember, I had thermocouples in the radiator to measure this, I'm not guessing.



At idle the thermostat doesn't stay open very long and the radiator cool the little bit of heat it gets is shed easily by the time it gets to the cold side of the radiator. If it didn't, then the engine isn't getting cooled.

The only time the radiator can heat the transmission fluid is when the cold side of the radiator is hotter than the transmission. And that can only happen is the engine is overheating.

I have had a transmission get hot on me idling in park. Sitting in the shade with the AC running while the family eats. It was in the 90's and my kids eat slow. I look down and my transmission had gone from 160 to 210+. How did that happen? I looked at the temp gauge for the engine and it was on its way to the danger zone. The AC was overwhelming the radiator and the engine was getting hot. So the transmission was picking up heat from the radiator in this circumstance. But a short drive trough town brought the transmission back down to 180 because the radiator was now able to shed the heat and was no longer overheating the engine.

Regarding the new transmissions: Thermostats have been used more frequently for a number of years now. As synchronous shifts become the norm, consistent fluid temps become more and more important.

Think about it though, if the radiator could be used to heat the transmission fluid, why would they need an internal thermostat for the transmission? It is because scenario #1 does not exist under normal circumstances. If it did, they could save the added expense and get shorter warm up times for the transmission, which as you eluded to, is increasingly important with the new designs.

On that note... How cool is it that GM and FORD can cooperate and design a 10speed transmission which is capable of shifting from 10th to 2nd in one shift!?

 

[MolaKule]

Quote:
The problem is that scenario #1 does not exist in nature, at least not outside of very extreme circumstances which will eventually result in an overheated engine.


And that is why many later vehicles have electric cooling fans to assist in cooling at idle, that is, once the temp gets high, extra air flow is forced through the radiator. My Nissan Frontier is but one example.


Quote:
Think about it though, if the radiator could be used to heat the transmission fluid, why would they need an internal thermostat for the transmission?


Because not all vehicle AT's have the internal circulation path to rapidly allow the ATF to heat up. My Nissan Frontier is but one example.


I don't think we can apply all of the Ford results to all vehicles. The Ford results apparently apply to specific engines with specific transmissions with specific circulation paths.