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Radiator ID + trans cooler confusion

90 Views 2 Replies 3 Participants Last post by  oldmarine
2004 Dakota Sport Plus Quad Cab AWD 4.7 Auto
Originally equipped with "Heavy Duty Engine Cooling".
According to Dodge it came with 55056518AA, which is discontinued.
Parts guy at dealership couldn't tell me whether this radiator came with internal trans oil cooler or not. He recommended OSC 13337 as equivalent replacement. This does have internal trans cooler.

Current (leaky) radiator does not have internal trans oil cooler. There is an external cooler in front of radiator. The cooler and lines setup looks very original--it doesn't appear to be an aftermarket add-on. I don't know if truck came this way, or if someone modified it (likely with parts from Dakota model that did have external cooler as it looks so "native"). But... this truck had about every option available added (I'll attach build sheet)--wouldn't an external cooler have been considered an upgrade over an internal one?

I can't find a "heavy duty" radiator (ie core thicker than standard 1.25") online that clearly doesn't have an internal cooler--either they indicate they have cooler, or there is no mention of it. Does anyone know of such a beast (thicker than 1.25" core that doesn't have internal cooler)?

To further complicate matters, the current radiator is only 1.25" core. So this beggars the question: do the HD rads (thick core) mount the same as 1.25 core ones? Seems if I'm replacing radiator I might as well get HD one, but if they are only available WITH internal trans cooler should I proceed? Should/can I just ignore the internal cooler and continue using external, or should I do what's necessary to use internal?

Apologies for being so wordy, but I'm likely going to have to order this online so I won't be able to inspect it first, and it will cost a lot to return it, so trying to do as much as I can to choose right part.


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That's interesting; until I read your post I had just pretty much assumed that they all would have had at least a tranny cooler built into the rad & that some would have the external aux cooler on top of that.

Anyway, I am sure I am not telling you about anything that you haven't already looked at, but for yours, Rock shows fittings for cooler lines on ALL of them. It's a bit ambiguous on some of them though; I cannot be sure from a listing conflicting with the data next to the part itself whether a couple of them have fittings for a tranny cooler or engine oil cooler? Or maybe the two are user's option & interchangeable?

Anyway, Rock shows one that is 1 3/4" & one that is 1 5/8". Both have fittings for lines to attch to, but I suppose one could take the fittings out & maybe find plugs the right thread & size to plug them with, or if you didn't ever plan on using them just go ahead & leave them open & hook your existing lines up to your existing external aux cooler?

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I put a new radiator in my '03 manual transmission Dakota about 3 years ago. The one I got from RockAuto had fittings for the trans cooler lines, but they had plastic plugs in the fittings. Since the transmission cooler in the radiator is completely separated from the engine coolant part, I just installed it with the plastic plugs intact. Have had no problems with leaks, etc. If OP transmission cooler lines are connected only to the external/separate cooler, I'd just leave it that way, plug the fittings on the radiator (if they're not already), and install it that way.

I would guess that the external cooler is more efficient than the cooler in the radiator, especially when the vehicle is warmed up. Coolant in the radiator runs at 195° (nominally), depending on what range thermostat is installed, and the transmission coolant tank is located in one of the radiator side tanks. So I'm guessing the heat exchanged is considerably less than if the transmission fluid is flowing through a dedicated cooler with a much larger area of the fins exposed to ambient air temperature, even if it's 90 degrees out. Just my opinion.
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