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Replacing factory GM oil/Tranny coolers with external units

scottishdave

scottishdave

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My 96' Tahoe, Vortec 350/4l60E and Has the factory Engine Oil/AT Fluid cooler built into the radiator.


Is it at all common or beneficial to replace this set up with a standard radiator and two separate coolers for the Tranny and Engine. I would really like a better performing AT cooler w/ gauge as the heat and hills here are hard on Auto Tranny's.
 
I wouldn't dink with the oil cooler setup just 'cuz it's more work. If it ain't broke, don't fix it.

Tranny cooler is absolutely common, and very wise, to keep the tranny happy. The only point of contention is whether to use ONLY the external cooler, or both the factory one first and then the external one. In my case I left the circuit in the radiator, and then added an external cooler. I find my truck is happier as the tranny heats up to operating temperature quicker that way; I mostly drive it around town short distances. I haven't had enough hardcore use on it yet to get a good feel for lengthy use.

The general consensus is the stacked plate design is more efficient than the tube-and-fin type. I like the B&M brand, but there's also Derale, etc. B&M has handy kits of the cooler with hardware and hose. Get the biggest cooler you can fit (physically largest, or highest GVWR rating.) B&M and and Autometer both sell gauge kits with the sender.

The kits come with these plastic ziptie things into your radiator which are begging to saw through it, bad juju. I chuck those first thing and mount the cooler behind the grille somewhere to the metal. I donno about new trucks (funny to call '96 new!) but on mine, I just used some angle aluminum, drilled some holes, cut it with a hacksaw or the Dremel as required. No welding or anything exotic.

Do read the instructions on mounting it, as I seem to recall that it's best to put the ports on the side, not the bottom.

-- A
 
Thanks...Much less worried about the Oil, and mainly the tranny.

If I used a nice external cooler and forgo the OEM one altogether, Could I maintain a factory style radiator and just leave the AT fluid inlet/outlet on the radiator open? Or would I need a radiator without the AT cooler?
 
scottishdave said:
Thanks...Much less worried about the Oil, and mainly the tranny.

If I used a nice external cooler and forgo the OEM one altogether, Could I maintain a factory style radiator and just leave the AT fluid inlet/outlet on the radiator open? Or would I need a radiator without the AT cooler?
Click to expand...

Oh no, no need to swap radiators. You can just leave that circuit open, or if you're really worried, plug the lines. (They're 5/16" inverted flare fittings, as I recall, which means 1/2"-20 threads.) Then just plumb the cooler to the factory fittings and off you go.

-- A
 
As was said above, lots of people run both trans coolers (in rad, and seperate)

If you bypass the trans cooler in the radiator all together, the trans will have a hard time warming up.
 
I was able to do mine without modifiying my stock lines, so when i have to remove my trans cooler, or something breaks, i can revert back to stock easily.

I listed parts in my build thread.

I ran my external in line between the rad and the top cooler line. Forget if that is feed
or return, but i thought through it when i did it.

Start reading here, lots of good info. You are on a newer truck, but i think the trans lines are hte same size.
http://coloradok5.com/forums/showthread.php?t=260975&page=2
 
dhcomp said:
I was able to do mine without modifiying my stock lines, so when i have to remove my trans cooler, or something breaks, i can revert back to stock easily.

I listed parts in my build thread.

I ran my external in line between the rad and the top cooler line. Forget if that is feed
or return, but i thought through it when i did it.

Start reading here, lots of good info. You are on a newer truck, but i think the trans lines are hte same size.
http://coloradok5.com/forums/showthread.php?t=260975&page=2
Click to expand...


:thumb:

Thanks....I knew I missed this place ha ha.

Selling the Blazer has made me think more about this Tahoe, and wanting to use it to take advantage of the miles of mild exploring trails here in CA and camping. Sort of a family, mild overland wheeling trip kinda truck.
 
evolve991 said:
Not to hijack the thread but has anyone used the inline type coolers to avoid too many in front of the radiator?
Click to expand...

I donno if they're efficient enough for tranny coolers. I know they're popular for power steering coolers, I use one for that.

-- A
 
sweetk30 said:
good info and ideas in here . http://coloradok5.com/forums/showthread.php?t=292058&highlight=tranny

if me I would do ext cooler and thermal valve for the cooler only when it needs it to be used . like the one I have linked in above thread link . but here ya go . http://www.summitracing.com/parts/DER-13011/
Click to expand...


:thumb:

Great info thanks.


Think I will run a nice B&M cooler, plumbed after the factory one like DHCOMP did. Will probably spring for braided A/N fittings for the lines. Then have a t-stat in the Pan and gauge somewhere in the cab obviously.
 
I like my temp sender for gauge inline of the hot out from tranny to show how hard I am working it .

I have it this way on my plow truck with th400 tranny .

most I have had is a few spikes up in the 210-220 range .

and my plow truck is a 1ton with 4.10 and 35 tires with HUGE fisher 8ft commercial plow.
 
Thanks SweetK that covered alot of questions, I'm surprised I never saw that thread before with all my 700 issues.
 
dremu said:
I donno if they're efficient enough for tranny coolers. I know they're popular for power steering coolers, I use one for that.

-- A
Click to expand...

I was thinking more of using one in addition to a good stacked type. Trans to radiator to front mounted cooler to inline and back to tranny. Overkill? Yes. But I'm tired of 700 problems.
 
So the point of maintaining the factory cooler is to allow the fluid to warm up to the desired operating temp.

If I were to NOT use the factory cooler and only use an external cooler with an inline thermostat switch set to open when the fluid warms, would that not do the same thing and allow me to keep things a bit more simple.
 
scottishdave said:
So the point of maintaining the factory cooler is to allow the fluid to warm up to the desired operating temp.

If I were to NOT use the factory cooler and only use an external cooler with an inline thermostat switch set to open when the fluid warms, would that not do the same thing and allow me to keep things a bit more simple.
Click to expand...
There's a couple different things at play here, both are important:

1) It's best to retain the in-rad heat exchanger no matter what. This is because it warms up your transmission quickly to operating range, but more importantly because it's a liquid-to-liquid heat exchanger. You can dump heat 4 times the rate from the trans into the antifreeze/water than you could from the trans fluid to air. That's due to the differences in heat capacity between water (4.18 J/°C g) and air (1.01 J/°C g).

2) Adding an aftermarket cooler after the rad can drop the trans fluid temp another several degrees after the basic required heat dumping is already done. Think of it as gravy on top.
 
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