I am familiar with heat exchangers in general,but what is the reason for the unit on the passanger side of the block, is it only for the trans? Reason I ask is I am going to install another trans cooler on the 350 dually. The small front unit seems to small to do any good. I have researched most all the postings on the trans coolers and am a little unsure. does fluid leave the trans and go to the cooler then the heat exchanger? this I assume replaces the usual flow thru the radaitor to heat/ cool the fluid? would the extra cooler be the last pass before going back to the trans? Or? I really think the lack of this one not having the factory under bed cooler Is why it runs a little hotter. I was in the desert this weekend it was snowing ,pulling any grade,2 to 6% would cause instant temp rises on the guage. I can really see summer being a problem when pulling the camper and quads. My 93 2wd has the factory superduty and I have seen the question come up by others. IT WORKS like you cant imagine. I hoping to get the same results with a aftermarket cooler and fan set up.
Any input on flow directions? I will be using a big non tube and fin, plate type I guess its called.
Thanks a bunch.

 

Yup, the one on the side of the block is the initial or "primary" oil cooler.

bob.

 

I just bi-passed the one on the block and took off the stock one up front. I went with a very large, tube- style up front. I was told not to re-use any of the factory stuff. Also to stick with larger, tube style coolers, any flat or plate style isn't good for flowand if your working it hard, may plug up quickly and leave you stranded. I intend on adding a second cooler and temp gauge before summer. I noticed the factory one is flat style tubing too.

 

Are you sure on the factory HD being a tube type? I havent looked real close at mine but it looks like a plate type. The front mount on both are the Dodge ones and they are the plate style. I can see your point on some of the aftermarket plate coolers. I stole the one off my cheby for the 4x4 CTD, but after it was out I realized the inlet and outlet tubes are pretty small compared to the factory stuff and would restrict the flow. Unless I can find one with bigger passes I will have to use a tube type it seems.

 

My front cooler appeared to be a continuous, square tube. As far as the inlet sizes on the replacement, don't worry about those. The ports for the inlet and outlet on the tranny are also a lot smaller than the line size and will be restricting flow anyway. Just make sure you flush it out good. The guys that built my tranny said they generally replace stock lines with over the counter brake lines because it's easy to work with and readily available, and again, the tranny ports pretty much make line size irrelevent. These guys also work on the county trucks (which see countless plowing miles). The only tranny they had come back was because the county didn't replace the cooler as advised. I cut my outlet lines where they bend to go to the heat exchanger, then spliced them with rubber hose (until I get the temp gauge) to make a straight line to the front. I haven't been able to get 1/2" rubber tranny line, so I cleaned the factory rubber/steel lines at the front, cut the metal tube off and used the factory 1/2" rubber line with brass nipples to reduce to the 3/8" line to connect the cooler. I was interested in a fan/cooler under the bed, but my flat bed is wood, and I think crud would drop down and fill it up.