Please learn me oill/atf coolers and plumbing.

So on the V8 Bravada, I've decided I want to split up the cooling system a bit. Currently it has one of those radiators with built in oil and transmission coolers. My guesstimation is that right now this arrangement is just causing everything to heat up everything else. And I don't think this radiator is going to be enough for this V8 in a cramped space under the hood of a heavy AWD mini SUV anyway.

Now for my questions:

Is there a general rule of thumb on how big these need to be?

Should I look into braided lines with AN fittings or are rubber and worm gear clamps adequate? (hard lines?)

Any recommendations are where to look for a radiator?

My goal is over build the cooling system to make it as reliable as possible and maybe future proof it for if(when) I decide 250ish horsepower isn't enough anymore.

the 4.3 radiator is plenty for the v8 swap in an s-series with a properly shrouded fan.

So revert back to plan A, which was don't change it if I don't have to?

this kinda ties into a question I have. What is the consensus on using an external A/T cooler as an engine oil cooler?

Chadeux wrote: My guesstimation is that right now this arrangement is just causing everything to heat up everything else.

That's true, but it's also intentional/beneficial, running oil/atf too cold isn't good.

I added a big one to my truck, but left it running through the radiator after the cooler. Used rubber hose.

Do NOT use the zip tie things they give you for mounting IMO.

If your going to be beating on a auto trans, any cooling is going to be beneficial.

For what it's worth I was told to do the same as Java for the same reason. They guys who were maintaining my car trailer mentioned it when I noted I was going to add a trans cooler. Too cold is in fact as bad as too warm. Rubber hose and clamps work fine. No need for AN there.

mad_machine wrote: this kinda ties into a question I have. What is the consensus on using an external A/T cooler as an engine oil cooler?

Main issue is a trans cooler probably won't flow enough for engine oil, best to use an engine oil cooler. For example, my Suburban has 5/16" trans cooler lines while the engine cooler lines are 5/8".

Chadeaux, if everything is in good working order, the stock cooling system will do the job, even with a V8. I would consider a good dual electric fan setup, that will help out and will give you more room for the 350.

IMHO, for an oil cooler you want a Mocal cooler, AN fittings and braided lines.

I think auto tranny cooler usually run significantly less pressure and rubber lines with clamps is probably OK there.

Another competitor in offroad rally ran a trans cooler as an oil cooler with rubber hoses and clamped lines. Worked OK for a while and made me think maybe I wasted money with AN fittings etc. on the Corolla. Then a hose blew off. Decision reaffirmed.

My take on it is this: If your oil temps aren't excessive, don't change it. Oil likes to be hot, drivers think it should be cool. The correct temperature is over 220 (at least somewhere in its circulation) but not over 250-ish for conventional. It needs to be hot enough to cook out stuff that shouldn't be there (especially condensates), but not so hot that it cooks the oil and additives.

Trans fluid works best at around 180-225. Lower temps protect clutches, but no clutch will be happy if its not getting hot enough to boil off any condensation. If you do a transmission cooler, run it through the external cooler first. The radiator not only acts as a cooler, but a warmer. It helps get the tranny fluid up to temp faster where its happy performing its hydraulic duties. Putting the external cooler first means that when the transmission is too hot, it can shed the bulk of its heat first before dumping massive heat into the coolant. This method accomplishes several things: 1) reduces load on the engine coolant, 2) prevents the tranny fluid from being too cool, and 3) still aids in faster fluid warmup.

Putting the tranny cooler after the radiator means 1) you're dumping the majority of the heat in the coolant, 2) you're shedding any warm-up heat benefit, and 3) possibly over-cooling the fluid.

As far as worm clamps, go for it. Most auto transmissions' cooling circuit only ever sees 30-40 psi, and that's only if there is a restriction. Since its free-flow, its unlikely you'll see more than 8 psi.

I put an external tranny cooler that was 10x18" with a 10" fan in a 78 chevy truck with a TH400 (so no lockup converter). It was a 4-pass cooler with big 1/2" tubes that had the twizzler-looking fins inside the tubes to increase surface area. Really did it right... hooked it up to a 215-degree sender to activate the fan and put an LED light in the cab so I could tell when the fan was on (and let me know that my transmission was heating up). I recall the light coming on once while towing 10,000 lbs up a mountain and it went off before I got to the top.