# 2010 Pathfinder Transmission Cooler: Bypass or Replace



## dustinlocke (Nov 20, 2015)

Hey all,

This thing has obviously been covered extensively -- and I think I've almost read it all -- so much that I think my next post will be a comprehensive list of all the best guides and stuff. But a lot of it happened in 2010-2012 and hasn't been updated. Here's my deal:

I just bought a 2010 SE 4x4 with 60k miles. Runs like a dream. No strawberry milkshake and I'd like to keep it that way. I spend quite a bit of time in cold (5-10 degrees at the coldest) places where I worry about cold fluid in the morning. I also intend to tow a rather heavy boat every now and again. My gut reaction when I read about the ATC problem was to just replace the radiator.

However, I've since read that even the aftermarket radiators are susceptible to the leak so replacing the radiator isn't a reliable fix and you have to bypass entirely. A lot of people have said this, but I haven't heard of it actually happening.

As for bypassing and adding an auxiliary cooler, this just sounds beyond my ability (which is essentially zero) and like it might not solve the warming issue.

Does replacing the radiator work? Any radiator replacement horror stories out there? Any recommendations on aftermarket radiators? Is there such thing as just buying the radiator from the 2011-2012 that didn't have any issues?

If not, is running colder fluid in the mornings going to damage my transmission?

TL;DR: I'd rather just replace my radiator, but I'm paranoid that won't fix the problem.


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## smj999smj (Jan 1, 2006)

I'm a former Nissan Master Tech and an owner of two R51 Pathfinders, an 06 LE and an 08 SE. I'm also a moderator at TheNissanPath.com, so I've read a great deal about other people's experiences. In my 06, I replaced the radiator with a $92 Ebay unit and it has worked great for 4 years. In the 08, I originally bypassed it last year and without issues, but have since purchased a Koyo brand radiator and will be installing it in the very near future.
Any radiator that has an internal cooler has the "potential" to fail, but, for the most part, it is usually a very reliable design that has been used in automatic transmission cars for decades (my '65 Mustang has an integral trans cooler in the radiator and some GM vehicles have transmission and engine oil coolers inside the radiator tanks). The factory radiators in the 05-10 Nissan Pathfinders/Xterras/Frontiers were made by Calsonic, which Nissan bought out around 2005. Calsonic has been an OEM supplier of radiators, exhausts and many other parts to Nissan for years. The issue with the Calsonic radiators during those years is a seal in the cooler that leaks inside the lower radiator tank, causing the cross-contamination. Nissan has since updated the radiator and has available the full-priced, genuine Nissan part, as well as a Value Line radiator that has a lower cost. Both are on the expensive side, though. Aftermarket radiators are much more wallet-friendly and I've yet to hear of any cooler issues from them. My friend did install a Denso radiator from Rockauto for $99 in his Xterra that did develop a small crack that leaked on the bottom tank. This surprised me as Denso is owned by Toyota and I have had good success with all of their aftermarket parts. Another at the other forum purchased the new, all-aluminum radiator from Stillen Motorsports for $350 but had some issues with the neck leaking, I believe.
For the environment that you'll be driving it, I wouldn't hesitate to replace the radiator with a new, aftermarket unit. If you want a name brand, Spectra Premium is a very popular choice. For me, it was cheap insurance compared to the idea of ruining a $5000 transmission! If you have blue coolant, I would highly recommend you get the genuine Nissan Blue coolant. It's pricey, but comes pre-mixed and good for 150,000 miles.


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## Chasexx007 (Jan 30, 2019)

smj999smj- I have a Pathfinder 2010 LE that i just purchased and would like to temporally bypass the radiator until i decide on permanent solution. The problem is that although there are many post & video on the internet none are specific to my 2010. Looking at my truck the hoses are not in the same places as earlier models. They don't look like they've been moved either everything looks factory. I'm pretty sure i have located the hoses that need to be moved but I'd like to confirm before bypassing my rad. Do you have or know where i can find a post / illustrations for a Pathfinder 2010 radiator bypass procedure? Thank you in advance for sharing your knowledge.


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## smj999smj (Jan 1, 2006)

They moved the auxiliary transmission cooler from the right side to the left side in 2008, so it is a little different. You'll need to get about 2' of 8MM (5/16") transmission cooler hose and some hose clamps for it and two 8MM (or, 5/16" caps). Remove the skid plate. Looking up from the bottom, behind the radiator, there will be a cooler hose that runs down the left side of the radiator. There will be a union in that hose, with pinch clamps. That hose will continue to the left side cooler fitting on the radiator. Remove that cooler hose between the left fitting and the union and the cooler hose from the right side cooler fitting on the radiator to the metal cooler line. I usually use Kooler Kleaner or brake cleaner to flush the transmission fluid out of the radiator. Use the 8MM caps and clamps to cap off the fittings on the radiator. Take the new cooler hose you purchased and install it on the hose union on the left side of the radiator and clamp it. Run the new cooler hose to the metal cooler line, cut to size and clamp it. Make sure you leave a little slack in the new hose. I usually install a plastic tie strap to secure it somewhere on the bottom of the lower fan shroud to keep it from just slapping around. Start the engine and top off the ATF (usually you won't need to add any) and check for leaks. If all is good, reinstall the skid plate.


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## garry19 (Apr 24, 2019)

smj999smj said:


> They moved the auxiliary transmission cooler from the right side to the left side in 2008, so it is a little different. You'll need to get about 2' of 8MM (5/16") transmission cooler hose and some hose clamps for it and two 8MM (or, 5/16" caps). Remove the skid plate. Looking up from the bottom, behind the radiator, there will be a cooler hose that runs down the left side of the radiator. There will be a union in that hose, with pinch clamps. That hose will continue to the left side cooler fitting on the radiator. Remove that cooler hose between the left fitting and the union and the cooler hose from the right side cooler fitting on the radiator to the metal cooler line. I usually use Kooler Kleaner or brake cleaner to flush the transmission fluid out of the radiator. Use the 8MM caps and clamps to cap off the fittings on the radiator. Take the new cooler hose you purchased and install it on the hose union on the left side of the radiator and clamp it. Run the new cooler hose to the metal cooler line, cut to size and clamp it. Make sure you leave a little slack in the new hose. I usually install a plastic tie strap to secure it somewhere on the bottom of the lower fan shroud to keep it from just slapping around. Start the engine and top off the ATF (usually you won't need to add any) and check for leaks. If all is good, reinstall the skid plate.


hello
I have 2012 pathfinder with 4.0 L engine. do you recommend doing this bypass and adding second cooler. what brand cooler should I use if you recommend it. I live in Dallas so temp. is very high in summer. if I only do bypass I think ATF temp. will be higher than normal, that why I was think of adding a second cooler but not sure what size or brand should I use.


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