How to: factory auxiliary trans cooler upgrade

[BeXtreme]

I should get a log with my 2011 Suburban. stock 5.3/mild built 6l80 w/billet converter, tru-cool 40k routed through the radiator cooler.

I see about 30-60 degrees above ambient year round when unloaded. Towing a 6k lb travel trailer I see no higher than 100 above ambient. I only see that when it is full throttle, up a steep grade, converter unlocked and in 3rd or 4th gear, for extended periods of time. Once I top out and it shifts back to 5th and locks the converter back up, it will usually cruise about 170 on the highway in 100 degree temps. No temp spikes when coming to a stop, in fact it usually drops temps fairly quickly when stopped.

I have taken temp readings with an IR gun when the engine is fully warmed up. Reads 210 on the gauge. Reads ~190 at the thermostat, ~170 at the inlet side of the radiator, ~130 at the outlet side of the radiator(where the trans cooler is).

So, if you are pumping 178 degree trans fluid(that's temp IN THE PAN, before it goes through the pump and converter) through the pump and converter, it's probably well over 200 degrees by the time it makes it to the trans cooler in the radiator. The in-radiator cooler is then going to try to pull that down to ~130 to match the engine coolant on that side. Then it goes into the front mount cooler where the ~100 degree air does it's best to cool it down more. You are likely getting a much better heat dissipation from the liquid/liquid interaction with a ~70 degree temp difference than you are from the air/liquid interaction with only 30-70 degree temp difference.

 

[L31MaxExpress]

I should get a log with my 2011 Suburban. stock 5.3/mild built 6l80 w/billet converter, tru-cool 40k routed through the radiator cooler.

I see about 30-60 degrees above ambient year round when unloaded. Towing a 6k lb travel trailer I see no higher than 100 above ambient. I only see that when it is full throttle, up a steep grade, converter unlocked and in 3rd or 4th gear, for extended periods of time. Once I top out and it shifts back to 5th and locks the converter back up, it will usually cruise about 170 on the highway in 100 degree temps. No temp spikes when coming to a stop, in fact it usually drops temps fairly quickly when stopped.

I have taken temp readings with an IR gun when the engine is fully warmed up. Reads 210 on the gauge. Reads ~190 at the thermostat, ~170 at the inlet side of the radiator, ~130 at the outlet side of the radiator(where the trans cooler is).

So, if you are pumping 178 degree trans fluid(that's temp IN THE PAN, before it goes through the pump and converter) through the pump and converter, it's probably well over 200 degrees by the time it makes it to the trans cooler in the radiator. The in-radiator cooler is then going to try to pull that down to ~130 to match the engine coolant on that side. Then it goes into the front mount cooler where the ~100 degree air does it's best to cool it down more. You are likely getting a much better heat dissipation from the liquid/liquid interaction with a ~70 degree temp difference than you are from the air/liquid interaction with only 30-70 degree temp difference.

Funny you mention that, I have some readings of just that. I was not loading the transmission, so it was not at full temp, but the readings are similar to what you see. It was also not quite as hot when I took these. The radiator cooler was doing a great job cooling the fluid to near the same temperature as the return cool side tank and the auxiliary cooler was doing a good job bringing the fluid down close to ambient. The added pan capacity helps stabilize the fluid temp when I run it hard as it takes longer to fully heat up more fluid.

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[L31MaxExpress]

Also interesting that your coolant runs a very similar temperature. My gauge runs just shy of 210F using the cylinder head mounted temp sensor. The PCM shows ~194-203F at the intake manifold. The thermostat around 185F. The inlet to the radiator shows 167F and the cold side tank in the 140F range.

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[BeXtreme]

Thermodynamics and heat transfer at work!

 

[pgutier1]

I actually did this with my 700r4 since I blew up the transmission that was in the truck after I rebuilt the engine and added some power. I was also strongly urged by my transmission rebuilder to use Dexron 6 after he fixed it. 12,000 miles later, still working great

I have a '92 k1500 suburban 350 4x4 also with a 700r4. How did you do this?

 

[pgutier1]

Lower tube on the radiator should be the cooler supply.

Upper tube on the radiator should be the return back to the trans.


Around here, it's probably better to have the hottest fluid go through the aftermarket cooler, then go through the radiator cooler, then back to the trans.

In a warmer climate, I might do things differently. Or maybe not. There's at least three ways to plumb the second cooler--ahead of the radiator cooler, after the radiator cooler, or in parallel with the radiator cooler. They all have advantages and disadvantages.


You're looking for power-steering return hose. I get mine at NAPA; but any decent parts store will have it.

Ideally, you'd use clamps that DON'T emboss a million diagonal ridges into the hose, like in the fuel system photo below. Those clamps will be harder to find since the PS return hose has a pretty hefty wall thickness.
Photo 1. ****** clamps vs. "Fuel Injection" clamps on a fuel system.
http://hbassociates.us/Fuel_Pump_9.jpg

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So you are saying the fluid is going up the radiator and not gravity fed from the top?? Sorry for the stupid question, just wanting clarification...

 

[L31MaxExpress]

So you are saying the fluid is going up the radiator and not gravity fed from the top?? Sorry for the stupid question, just wanting clarification...

Apparantly that varies by model. The older G-vans, my 97 Express and my 99 Tahoe all flowed down with gravity. I have not had one that flows up, but I believe Shurkey in his claim that his flows up. Running the cooler reversed will make the fluid run a bit hotter though as the coolant is coolest at the radiators outlet.

You would need to trace the fluid flow to find out on your truck. On a 700r4/4L60E cooler ports on the transmission, the bottom cooler port is out to the coolers and the upper is the return. On my 4L85E the front port is out to the cooler and the rear port is the return. On the older 4L80Es the outlet port is in the same spot, but return port is the lower port that is further forward. On my 97 van the front port connected to a line to the top of the radiator, then a short line connected the lower radiator port to the passenger side of the auxiliary cooler, then the outlet of the auxiliary cooler on the driverside returned to the rear of the transmission.

GMs plumbing of the auxiliary cooler is also puzzling. I have seen some applications (my 93 Fleetwood I had) where it is plumbed in before the radiator cooler and yet others like my Express and Tahoe where it was plumbed in after.

 

[vince72]

I have this upgrade on my list of things to do, since my truck does not have this will I have to replace the lines or can they be make to work with my existing lines?

 

[evilunclegrimace]

I have this upgrade on my list of things to do, since my truck does not have this will I have to replace the lines or can they be make to work with my existing lines?

You will have to replace the line that goes from the trans to the top of the rad with a line that goes from the rad to the cooler and install a line that goes from the cooler to the top of the rad.

 

[vince72]

So the transmission fluid will go thru both radiator and tran scooler?