HAZE

last week i took my truck to the shop for the 4wd issue, apparently i fixed that. so i figured while i'm there i'll get the trans and rear end fluid changed. ended up getting a high capacity hy-tech pan, figured it'll drop my temp. they suggested a after market cooler. i started looking at mine, figured that it was big enough. my temp is more stable but has'nt dropped much, so i start looking at the position and following the lines. is it my imagination or does my trans cooler line go into my radiator tank ? is that how they "cool" the trans on truck w/o the external cooler ? this setup seems really stupid. are they just being cheap and lazy ? it does'nt make any sense to me to route trans fluid, something you want as cool as possible into that hot environment. is this making any sense to anyone ? if so has anyone routed the lines differently so it only goes to the cooler ? i figure i can just pull those lines, plug the holes and connect the cooler straight to the trans. any reason not to do this ?

Hit Man X

Yes think in terms of heat transfer (perhaps fluid dynamics) and you'll understand the radiator can remove more heat than a cooler alone can. The rad pulls most of the heat out...then goes to the aux cooler for more heat dissipation.

The coolant absorbs the heat from the ATF and disperses it through the engine coolant. Also, KEEP THE LINES TO THE RAD.

Chingon

iTrader: (1)

I hooked my cooler in a series with the stock heat exchanger. So the hot fluid goes from the tranny to the cooler, out the cooler to the stock heat exchanger (what you pointed out), then back to the tranny.

HAZE

so what your saying is, the coolant goes from the trans into the heat exchanger then to the external cooler. in order for that to be effective the trans fluid going in would have to be significantly hotter than the coolant or no heat tranfer would take place. does anyone know off hand where the trans temp is measured ? i ask because my trans temp reads around 155-160, while my coolant temp is generally 175-185. it must be read as it's going back in to the trans, if not the routing is heating the fluid. so has it been tried ? just wondering. e

Hit Man X

From tranny to rad. Rad to aux cooler. Aux cooler to tranny.

I'm not sure but... I do believe radiator coolant is going to be considerably less than the rest once it's passed through also...just like the ATF. I think that coolant is measured somewhere in the block. Coolant absorbs heat. So like since the heat exchanger is in the rad with much cooler coolant (passed through the rad) it'd be at a lower temp than the ATF right?

I'd think the best place to measure ATF temp would be in pan sump. In any event, do not bypass the ATF going through the rad.

HAZE

ok, ok ,i won't bypass it. i'm asking because i don't know. i'm just taking pieces of the puzzle and trying to build a theory. here's the pieces, and yes i know there is alot of room for error here. my vsc is set as low as it will go, when logging they consistantly come on between 175-185 [measured wherever the ect sensor is] my assumption was that this was the temp, since the probe is in the radiator. i realize that without actually measuring the coolant at the radiator i can't be sure. my trans temp is somewhere between 155-165 on average. i was told that the trans would last longer if i could run it in the 140 range. so unless my coolant is on average 140 or less , no matter how many trans coolers i have, it will be countering my attempt. i understand what your saying, if the fluid is coming out of the trans at say 200 degrees and the heat exchanger is dropping it to say 180, then yes it is helping. does anyone have any actual info on trans temp before it hits the exchanger ? i wonder if i could hook up some sort of in line temp guage to test this. do you think it would be very accurate to shoot an infrared thermo at the line right before it goes in the rad ? . e

HAZE

this has me curious now, i've talked to three different guys. one at a speed shop, a friend who's a mech/pit guy for an off road race team and another guy i know who races sportsman class. they pretty much all had similar views, i know these guys are running fairly short distances under extreme conditions. they all said when they ran i pretty much bone stock classes with auto trans they ran multiple trans coolers w/o the heat exchangers. the truck guy said they ran a huge trans cooler with a dedicated fan. i think im going to try it, see what happens. can always go back. i need skid [splash] plate anyway, thinking of drilling many small holes mounting a cooler to it with a small fan. found one at the auto parts store thats 10 1/2 ". what the hell, i'll let you know what happens. e

marc_w

The engine-coolant part of the tranny cooler system is needed in very very cold weather.

Supposedly ATF can gel in something like -20*F, and basically clog the cooler and cause all kinds of problems inside the tranny - the engine coolant helps get the ATF up in temp so that doesn't happen.

-20*F may sound insane to some, but even here in MA it got as cold as -12 this past winter.

Chingon

iTrader: (1)

We live in southern California. We don't have that problem

HAZE

i wondered about cold, but like chingon said, it does'nt get that cold. even when i go to mammoth, it rarely drops below zero. but thanks for the input. was thinking maybe i'll run the other cooler inline after the factory unit and see where my temp goes. also need to get a better guage/sending unit for the trans and coolant. was logging yesterday and watching the gauge and the reading in efi live, the fans seem to kick in at 175 [on efi live] as soon as they kick in i can see the temp drop. but on my dash gauge i read 185-195 and it does'nt react just sits there, then it will drop very fast. pos. wonder what trans temp i'm really running ? actually efi live is reading off the same sending unit, maybe just a gauge. e