Trans cooler - Bypassing the radiator?

[Billy V]

I just purchased an auxiliary trans cooler kit from the chevrolet. GM part #12546251
The kit came with rubber hoses and an 8"x11" Cooler made by Long mfg.

I don't like the idea of rubber hoses, so I went to an Aamco dealer to ask if they would install it with metal lines......
They said they would only use rubber and wanted to Bypass the radiator tank????
He also suggested a larger cooler 12"x12" True Cool Brand.

Is it ok to Bypass the radiator?
Even if I go with my 8"x11"?
Should I use the larger cooler like they suggest?

[HowieE]

I have bypassed the radiator on my last 4 towing vehicles.
I use a fan cooled cooler on the output side of the trams mounted on the frame just under the drivers seat with a thermostat set at 165 degrees. That in turn goes to the stock cooler mounted forward of the radiator. My trans runs at 150 degrees in summer while towing as long as the convertor is locked.
I have taken this approach because the radiator can only add heat above the temperature I would like the trans to run at because the trans coil in the radiator is subject to temperatures above my desired running temperature.
In the past i have covered the factory cooler during winter mounths. I have not covered this one on my 97 just because it is quite a mess to get to it. The trans has been running at 100 degrees so far this winter. Yes I would like to cover it.

[JoeyD]

Howie, Did you just run new lines from the trans to the new cooler under the seat?
I want to remove my trans and engine oil cooler from the grill to under the truck to make room for my intercooler. Thanks for the info.

[DmaxMaverick]

Billy

There are two sides to this argument.

As Howie points out, the radiator can add heat to the ATF under certain circumstances. More than likely, it will not add heat above safe levels, though it may not be able to remove enough heat under high demand (heavy towing, grades, etc). The core for the tranny is on the cold side of the radiator. If your engine temp is at 200

[6.2L Driver]

the tranny cooler in the rad is on the hot side of the rad, where the coolent is getting dumped on it right out of the block at 195 degrees. The engine oil cooler is on the cold side. with just the rad tranny cooler with coolent at 200 degrees on it your tranny temp will run at 230 degrees all the time. having put in 10 trannys in my 82 6.2 i made a few changes. one was an exteranl cooler that has droped my temp to about 130 degrees in the tranny. I also had to shorten the linkage that goes from the IP to the TV cable. With a pressure gauge on my tranny I could see that i was not getting a oil pressure rise in my tranny when the throttle was opening.

[LanduytG]

I have run my trans both ways and I recommend leaving the rad inline. When the torque converter is unlocked for long periods of time I have found it to run cooler with the rad inline.

Greg

[rjwest]

Tried to bypass radiator on my 96, RAN TO HOT WHEN
IN TRAFFIC, to slow to get air through front cooler,
NEED FAN for slow speed.

[jjgmc96]

this time of year my trans temp gauge never moves on my ride to work. 20mi. i was thinking about the bypass set-up i saw in summit to bypass both coolers until the temp gets to 160, any thoughts?

[computer monkey]

Hi Billy V
FYI Long makes B&M coolers. I am running two coolers on my Suburban. One if front and one underneath the bumper (with 12inch fan). I experimented with leaving out the radiator without good succes. The radiator will take out the biggest bulk of heat when slow pulling or while at a stop. With the other coolers, they will lower the temperature to a more respectable leveler.

Ralph

[HowieE]

Joey D
Yes I had to cut into the trans line and run rubber hose, came with the fan/cooler, back to the mounting location.
Yes as several have mentioned above the trans does run very cold in the winter if I have not covered the OEM cooler. The fan/cooler will come on in the dead of winter if in stop and go traffic or towing and hold the trans at 150 degrees or a little less while the convertor is locked.
An observation. I beleave the net trans temperature, in the summer months, while the convertor is locked in my setup is a function of the air flow coming back off the engine and not internally generated heat. I say this because if I start off towing with a cold engine and trans and reach road speed and convertor lock in the first shift sequence it will take a very long time for the trans temperature to reach 150 degrees.
As far as locating all cooling behind the radiator or under the truck I would consider the above and the increased air temperature you would be working with as your cooling source. At the least I would increase the size of the coolers your only location was behind the radiator.