I'm thinking of adding a second factory plate style trans oil cooler above the intercooler on my '93 RAM 250 Club Cab to improve the cooling for the A518. Would I be better off running 2 coolers in parallel by installing Y-fittings in the lines or should I run the 2 coolers in series, with the output of the first going to the input of the second one?

I have two extra factory plate style coolers that I picked up from PickNPull. I thinking of using the extra one for an engine oil cooler. Do these trucks even need auxiliary engine oil coolers?

 

I have an oil temp sensor installed above the filter, just because I had a gauge and was curious. It rarely goes above 200 and then only briefly when under a load.

Do you do a lot of towing?

 

Not a lot but when I do it's heavy loads (8000+ lbs trailer and load) and it's up the foothills of the Sierra's, so a few steep grades. Coolant temp will get past the 2nd to last mark on the gauge briefly.

As for transmission cooling, even running around town would benefit from cooler fluid. It never gets very cold here.

 

I would do it in series...cool the fluid through one, then cool it again through the second.

 

I agree...Routing through two "tee" fittings just increases the chance of a leak too......Ben

 

The only reason I could possibly see for running them in parallel is to minimize flow reduction in the cooler circuit. By running them in series you're lengthening the cooler circuit even more, and theoretically increasing resistance and reducing the flow rate. That said, any flow rate reduction may be minimal to the point of being irrelevant--this isn't something anyone has ever measured as far as I know, so all we can do is talk theory. Not trying to dissuade you from running them in series, just wanted to point out something, however minimal the issue might be.

Also, people talk a lot about how the Cummins doesn't need any additional engine oil cooling--that the existing cooler is perfectly adequate. However, as we add bigger injectors and tweak the pump and perform other mods which significantly increase power beyond what Dodge imagined with the existing cooling system, the discussion of adding additional engine oil cooling becomes perfectly valid.

All that said, I'd probably put both coolers on the transmission. Unless you see regular subzero temps in your area, you literally *cannot* cool transmission fluid too much. I would also run them in parallel. The issue of that creating more potential for leaks is simply an issue of not half-assing it when doing the plumbing. Do the plumbing right and you won't have an issue.

 

Good point Midnite. When I was researching adding a cooler the main thing was orifice size and not to restrict flow.

I've got a double deep pan but not had a chance to put it on yet to see what effect it has.

 

I’m sure I can plumb it up so it doesn't leak, so parallel it shall be. That, plus the deep B&M cast aluminum pan should help keep my transmission frosty!