Ken - Thanks. I confirmed that the front port on the tranny goes to the top port on the radiator, so that fits.

Ok, given that I want it to go through the cooler first and radiator second I'll need to revise the plumbing so I come off of the hot/top line and go into the aux cooler, then back into the top port on the radiator. Right?

And, does it make sense to do that? Everything I find, like B&M's installation guide, says to put it after the radiator's tranny cooler. However, I have found a few hits on threads where other guys are thinking like I am - it is possible to over-cool the ATF. In fact, B&M says that the optimum temp is 160 to 200 degrees F, so they seem to say that it at least needs to be up to 160.

My thinking is that the radiator is going to be running at something less than 195 degrees in the winter because that's the 'stat I'm running. However, as I think about it I really don't know how cold a radiator runs in the winter, so I don't know if it'll warm or cool the fluid. But, I'm pretty sure that placing the aux cooler after the radiator's cooler will chill the fluid quite a bit in winter.

On the other hand, placing the aux cooler ahead of the radiator will tend to bring the temp of the fluid up higher in the summer as the radiator can easily get to 220 degrees. And, that's well above the operating temp they recommend for the fluid, which implies placing the cooler behind the radiator.

Too much analysis?

Well, I did learn one thing from this - B&M says to NOT point the outlet tubes down as that tends to trap air in the cooler and inhibit cooling. I would have thought that so much fluid passing through would push any air out of the system.

Help! Thoughts?

 

No, I don't think so.

I thought about that a lot too, especially when I towed with automatics.
Because locally we have mild winters & summers (occasional frost in winter, & not often over 90F in summer), I just stayed with the factory arrangement.

But with greater extremes, I think there would be disadvantages with the trans > rad > aux > trans plumbing.

1. The engine coolant is being subjected to extra heat from the transmission in hot weather/heavy load situations, when it least needs it; but going trans > aux > rad > trans would reduce that........benefiting both the engine & transmission.
2. And as you mentioned, the over-cooling issue in winter especially for the first few miles after start up, & beyond in sub-freezing temps.

But the trans & vehicle manufacturers must be fully aware of all this too, so IDK.

I guess the ultimate would be a thermostat-controlled arrangement, diverting fluid to either the radiator for warming, or a big external cooler, as necessary.

 

For exactly the reason you state, aux cooler goes after radiator. The radiator can get hotter than the recommended temp range for the ATF.

I would put the cooler in with the fluid ports towards the side with the factory cooler lines. In on the bottom and out the top would prevent air from entrapment.

I would rather have the fluid too cool than too hot.

The factory coolers on late models are all after the radiator...

 

The coolant can be up at that temp as it leaves the engine; but exiting the radiator, it (& the trans fluid) should be a lot cooler.

 

Does Rusty have an under frame receiver hitch?

 

Ok, Don has convinced me that the aux cooler should go after the radiator. If the factory is doing it that way then they must have thought through it.

Ken - You are right about the coolant being cooler than the engine - otherwise it wouldn't cool the engine. Duh! What was I thinking?

Bruno - No receiver hitch at the moment, but I have the humongous one I took off of Dad's truck that I've been thinking about bolting on Rusty. That 20' wide trailer I'm using weighs enough that it really should be pulled using a receiver hitch - and I have one so why not?

 

Are you considering putting a new one on Dad's and leaving the humungous one on Rusty? Also, is it the one in the corner of the shop that needs to be powder coated?

 

Hadn't really thought about it. That is the one that needs powder coating. If I found one that hid better than that one I might put it on Dad's truck. But I'll put this one on Rusty for now to tow with.

 

Gary, one other thing that is on my Superduty is a thermostatic/pressure bypass. Cold fluid is harder to pump, so the bypass will send the fluid back to the trans pan instead of the cooler.

And you could always bypass the aux cooler in winter...

 

Speaking of trans coolers. My truck has three. The internal radiator. An factory external and an aftermarket external. I bought it that way. LOL.

 

Thanks. If Dad's truck ever gets an auto I'll consider that. But Rusty had better be happy with this cooler. Back when I rode motorcycles I put a similar cooler on some and that worked well - although later I realized I didn't ride in cold weather.

 

Lots of other things going on today, but got a few things done on Rusty and some things started:

• Transmission: I realized that I had no clue when the tranny's "filter" was last changed. So, with 144K miles on the tranny and no fluid in it I thought it was time to replace the filter and dropped the pan. Wow! That's the cleanest tranny inside I've ever seen - as seen in the first picture. Then I installed a drain plug in the pan as I've vowed to never replace a pan w/o a drain. And after that I powder coated it and reinstalled it - as shown in the blurry second picture, but I think you'll get the picture.
• Exhaust: Well, I think the plan may change on which system to use. I put the single exhaust in place and found that the tail pipe won't clear the rear of the springs - as shown in the third pic. Granted the spring will rotate up when the truck is back on the ground, but I can't bolt it up while on the lift. So, I put the Magnaflow system in place and it just clears, as shown in the last pic. However, that means I have to weld the driver's side exhaust pipe back on since the only way to get it off of Dad's truck was to cut it off just behind the muffler. But, when I mocked it up that pipe comes up about 2" short of the muffler. Did it shrink? Oh well, but it brings up the question, again, of which way to go. I have a piece of pipe that would let me add the 2" to the Magnaflow system or add it to the quiet system that came off of Dad's truck initially. I'm leaning to going with the Magnaflow system, but want your thoughts.
• Tranny Cooler: Got 8' of 3/8" high-temp hose and some split loom today and will soon redo the aux cooler mounting and plumb it up - after the radiator's tranny cooler.

 

That C6 looks as clean as mine did.

 

Hard to believe that a 32 year old transmission with almost 150K miles on it could be that clean. No gum or deposits anywhere, not even in the bottom of the pan. Probably says the aux tranny cooler did its job.

 

Mine has 231,000 as far as I know. My transmission has a sealed power transmission filter with a metal gasket. So I know it's at least had a filter change at some point. The bottom of my pan had just a very light film of deposits at the bottom. My transmission shifted very sluggish for a long time so it may have had some premature clutch wear. bad modulator valve and a broken accumulator valve spring. All fixed now though. I doubt it has ever been rebuilt, due to the horribly worn out rubber molded servo piston. That thing so was hard, and barely sealed.