[gdneely72]

Hey guys, wondering if someone can answer a few questions to help those of us that are considering an aux transmission cooler. I wanted to thank everyone for all of the info in this thread as well.

First, what cooler options have been used and do we expect that any of them would be sufficient if the stock cooler was bypassed?

Options I have seen in this thread include:
1. Derale 13503/33503 Plate and Fin
2. Derale 13750 with elect fan (good for low speed towing or if not mounting in front)
3. CXRacing OC-KIT-CANYON28D-STOCK or BIG (assuming capacity similar, just sized diff)

@DieselDrax is your stacked plate cooler item 1 or something else?

I see a mix of 6 and 8AN sizes. I assume 6AN would be sufficient since the stock lines are 3/8"?

Early in this post, a benefit (maybe the only one) of the stock setup was heating the trans fluid with engine coolant. I wonder how this compares to the thermostat that mounts directly to the transmission (would the trans fluid heat faster internally without help of coolant?).

The thought of bypassing the stock cooler was brought up due to an alleged failure, but I only saw something about Nissan owners experiencing this. Or was I mistaken and this has happened on a 2.8?

Thanks in advance!

 

[gdneely72]

I think I'm the only person on these forums to have the exact issue I did with the cooling system... haven't seen many posts about issues with the diesel trans cooling system, aside from someone's buddy making an error above.

You're not losing much if you entirely bypass the stock cooler. I'm team Derale after getting a pinhole cooler from CX Racing and seeing that my experience is by far not unusual with a quick google. I'd still pressure test any brand you get, but I'd encourage you to go Derale 13750 with the fan. You can always not use the fan but if you live somewhere hot, or mountainous, or find yourself towing... would be nice to have. The thermistor makes it so it will automatically turn on, or it can be wired to be push button if you want. With a couple clever connectors, it can even be automatically turned on when enabled via push button, or manually controlled with that push button. I can make you a diagram if you need but it's nothing crazy.

Re:warmup - I don't think the coolant warms it up that fast. The IR thermostats only allow a small amount (~10% or so I think they say on the website) to circulate past the thermostat while it is closed. IE if you have the thermostat, it will allow ~10% to cycle through the lines + radiator+ aux cooler before fully opening at 165*. If you deleted the factory cooling, it would just cycle that 10% through the lines + aux cooler and return it.

You can see what the stock cooler looks like in post #8:
View attachment 484107

For ease of installation, if your stock setup is in good shape (isn't corroded, leaking, or giving you problems), I'd say you might as well include it. It's not difficult. If you ran in to an issue on the trail, it would be quite easy to bypass it with some form of coupling (whatever makes sense for your setup, could be a male to male AN6, or a barb to barb... or whatever). I always carried a few feet of 3/8" fuel line on the trail with some hose clamps and barbs... I added a couple AN6 couplers to that same bag.

Thanks for the reply guys. I live in South Texas so it does get hot, but stock setup is in good shape since we don't use salt on the roads during winter. I installed a PML deep pan last year so think that has helped reduce peak temps a little, but I am monitoring trans temp to decide if aux cooler is needed. I haul a ~4000 lb boat to the coast occasionally so will see how the peak temp looks in a few weeks, but if I remember correctly, I didn't see over 200 deg during a trip last July which was hot. It seems that if you are under 200, you shouldn't be hurting the fluid. Please correct me if I'm wrong.

My extended warranty is almost up so am planning on getting the GDE tune. I understand that may change shift points some, but I don't think that should impact trans fluid operating temps much (@DieselDrax can you confirm?).