Tranny Coolers

[jauguston]

2115,

You are missing the fact the transmission cooler is at the outlet side of the radiator core not the inlet side that would have thermostat temperature water. The water the transmission cooler sees has already been cooled by the radiator.

Jim

 

[subway]

thats what i was thinking, not arguing with anybody or trying to fan flames though. if a radiator was working properly it should be much closer to ambient temp at the bottom than engine temp. i agree with 2115 that a quality aftermarket cooler would probubly outperform stock.

i think i will slinker back to my 5 speed now, no coolers at all to worry about

 

[sle2115]

The coolant at the "bottom" of the radiator would not be 200 degrees but your point is a good one.

Don't bet on it. Remember, emissions work best at high temps, hence the 200+ degree thermostats and high pressure caps of the day which equal HIGH coolant temps and pressures. If the system is running 240, the radiator would have to be VERY efficient to cool to 200 degrees, not to mention, not all coolers are in the bottom of the tank, GM uses a much more efficient crossflow design with side tanks. While this is not all applicable to our older trucks, it is to newer engines which run much higher coolant temps and still use the same type of tranny cooler.

I would also guess that if your truck runs 230 or so, as many have said, the bottom tank would be approaching 200 degrees on long runs, but would have to temp sense this to have proof. Would be cool to make a 3 or 4 hour run pulling a trailer and then hit the radiator top and bottom with a point and shoot temp gauge.

 

[sle2115]

2115,

You are missing the fact the transmission cooler is at the outlet side of the radiator core not the inlet side that would have thermostat temperature water. The water the transmission cooler sees has already been cooled by the radiator.

Jim

Not missing that point at all, but the radiator does not remove all heat from the coolant. If you put 230 degree water in, what is the outlet temp? This is also variable with duration of heat cycle etc.

My transmission in normal operation would run 160 degrees with just a good quality, good size transmission cooler. I would venture to say that if your coolant temp is 230 or thereabouts (higher in newer vehicles as 240 is pretty common for emissions) then you would probably never reach a 160 outlet temp and could actually be heating your ATF. Much depends on radiator efficiency, which also depends on many things, like condition of radiator (prolly not great in these old trucks), flow (plugged or restricted internally/externally and if there is a condenser in front of it), etc. and would be hard to find data on because of these variables. I don't have a auto tranny now, but had inlet and outlet gauges and tested with and without radiator cooler in line and saw better temps with it not in-line. I also saw better temps with the air/fluid cooler AFTER the radiator cooler rather than before, which supports the fact that the radiator was actually warming the ATF.

These are just my observations and my .02 on the things I haven't tested, such as radiator efficiency. Anyone have any numbers on that?

 

[sle2115]

thats what i was thinking, not arguing with anybody or trying to fan flames though. if a radiator was working properly it should be much closer to ambient temp at the bottom than engine temp.

Not to be a smart ***, but if that is the case, I have never seen one working right, crossflow (GM) or verticle tube (Ford). Run your truck for a couple of hours, then grab the bottom tank, bare handed, then report back!

I bet you will find it will not be near ambient temp!

 

[sle2115]

Here is a for instance quoted from http://www.stewartcomponents.com/tech_tips/Tech_Tips_6.htm


Following is a typical engine:

Inlet temperature = 180 F
Outlet temperature = 190 F
Coolant flow = 100 GPM
Specific heat of coolant = 1.0
1 HP = 5.2769885 GPM 1 F
{ (Outlet-Inlet)CS} / 5.2769885 = HP loss
{(190-180) 100*1.0} / 5.2769885 = 189.5 H

So this is stating a 10 degree drop from outlet to inlet. So, if your engine is running higher outlet temps, it will be running higher inlet temps as well. What does this have to do with anything, it just supports my point that if you are exposing your 160 - 170 degree ATF to engine coolant, it isn't actually cooling it!

 

[h2odrx]

that stuff was from...... Cooling System Basics for Spark Ignition Engines
SuperFlow Advanced Engine Technology Conference, December 7, 1992

 

[sle2115]

that stuff was from...... Cooling System Basics for Spark Ignition Engines
SuperFlow Advanced Engine Technology Conference, December 7, 1992

Does it matter what it was from? I was only using the inlet and outlet temps, 10 degrees difference. So what is your point?

To think a bottom tank would be much more than that is ridiculous. If you don't believe me, do what I suggested, touch it after a couple hours running. The radiator does not drop the temp that much, which was my whole point, doesn't matter what or when (gas/diesel or 1992 or 2002) the temp in and out hasn't changed that much, and if it has, it has only gone up, which supports my point, the radiator is often not cooler than the ATF, so how can it cool it?

If you have newer data showing something different, then post the link, I would love to see it. If not, then go with what you feel is right as will I.

 

[jtate]

trans cooler

i have a question on this subject. the previous owner that owned my truck must have changed the radiator, and the radiator that he put in was from a standard trans with no inline cooler in it. he added a aftermarket cooler and thats all i have, do you think this is bad for my trans?

 

[sle2115]

i have a question on this subject. the previous owner that owned my truck must have changed the radiator, and the radiator that he put in was from a standard trans with no inline cooler in it. he added a aftermarket cooler and thats all i have, do you think this is bad for my trans?

Personally, I would put as big of tranny cooler as you can fit as well as a temp gauge and see what it says. If it stays under 200 degrees, you will be fine. 160 to 170 will give you very good longevity in my experience, but I wouldn't worry about it, especially if you can monitor temp. As I said, I ran a 383 in my chevy with a TH350 and a high stall converter, read excessive heat, and I cooled it quite well with just a large trans cooler but kept an eye on it. If I really ran the crap out of it, I could get it to 175, but it would drop right back down in the 160's very quickly. The type of driving will influence trans temp as well, if you do a lot of low speed pulling, where airflow is limited, you will see higher temps. If you are moving 35 MPH or more, you will see them come down quickly if you have good flow to the cooler (no major obstructions).

I even pulled a tandem trailer with a car on it a couple of times, it would get in the high 170's and maybe even in the low 180's, but it never got over that and that was with a high stall converter slipping pretty much constantly!

 

[Mr_Roboto]

Like Sle says, get a trans gauge and see how it runs. Cheaper than a new radiator (or new trans if it doesn't stay cool enough).

We could debate all day long about whether it will be OK or not, but a gauge won't lie.

 

[96_Bear]

Hey guys why is it that when you use reverse a lot no matter how big the cooler(s) are that these E4OD's still like to get hot. When plowing snow with my dual coolers I can be cold (right after startup glow plugs cycle off)go 300ft to the neighbors driveway and back up his 250ft (slight hill) driveway twice and can make the trans go to 180 or better in like 5 min? A guy that builds pulling truck trans said that it was because they bypass the cooler when in reverse is this true... and can it be made to still cool?

 

[Mont91]

If I remember, tomorrow when I go get fire wood I will tape an indoor/outdoor sensor to the radiator outlet and see if it gets above 199. Temp is supposed to be 30 tomorrow so it will not be a good test.

I have never seen a tranny cooler in the inlet tank, who did this? Chevy put their Engine oil coolers in the inlet tank and engine oil starts to break down at about 230 ddegrees so these engines must not have been running above this. Why is a cross flow radiator better than a down flow? I know some of the chevy cars ran at 240 degrees on hot days and the max operating temp on the IDI is 245. My '91 runs 240 on hot days with a big load. The temp guage reads 3 degreas less then thermostat housing temp.

BTW most if not all autos have a thermostat that bypasses the cooler until the tranny reaches operating temp.

 

[Mike]

 

[sle2115]

I have never seen a tranny cooler in the inlet tank, who did this?

No one that I know of.

Chevy put their Engine oil coolers in the inlet tank and engine oil starts to break down at about 230 ddegrees so these engines must not have been running above this.

I think you are a little low. If coolant temp is 230, the metal temp of the engine will be higher. Most oils will handle 230 coolant temps with no problems. Not to mention, in vehicles where I have run a oil temp gauge, the oil was ALWAYS 20 or so degrees hotter than the coolant.

Quoted from http://www.carjunky.com/news/motor_oil/mom2.shtml

The flash point can be an indicator of the quality of the base stock used. The higher the flash point the better. 400 degrees F is the absolute MINIMUM to prevent possible high consumption.

Today's engines are expected to put out more power from a smaller size and with less oil than engines of the past. Therefore, the engines run much hotter than they used to. That puts an increased burden on the oil.

Even the best petroleum oils will have flash points only as high as 390 and 440 degrees F. Some actually have flashpoints as low as 350 degrees. For today's hot running engines, this is not nearly enough protection. Just about any synthetic you come across will have a flashpoint over 440 degrees. Premium synthetics can have flashpoints over 450 degrees with some even reaching as high as 500 degrees.

Why is a cross flow radiator better than a down flow?

Longer tube length/more surface area as well as longer coolant in tube time, often wider tubes etc. Cooling ability is controlled by surface area and contact time of the coolant with cooling fins.

One of the most efficient transmission coolers I have used is the one Mel suggested, the B&M one. It has very wide, flat crossflow tubes, is small in general size but has more surface area than the bigger ones, and in my experience, the largest one will have no problems cooling a normally operating transmission. If you pull a lot, you might want to run two. The one I had on my last truck was about 8 x 11 inches, and about 1 1/2 to 2 inches thick, so you should have no problem finding room for 2 of them. Here is a link to one at Summit Racing.