About to have new radiator installed... bypass still advisable?

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BuddyC
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Car: 2008 Nissan Pathfinder LE

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I have a 2008 V6 PF that I performed the tranny cooler bypass on years ago. My radiator just went bad so I am getting it replaced in a couple days. I ordered the Denso brand one off Rock Auto. Does this radiator still have a tranny cooler attached to it? If it does, is it supposed to have a design that absolutely prevents the SMOD and therefore I can undo the bypass and reattach the transmission lines to the radiator like factory? If this is true, what is it about the design of newer radiators for the PF that prevents this? I am not doing any towing, so if there is still an eventual chance of the cooler on the Denso failing and causing the SMOD, would I be better off leaving it bypassed? Or will I gain enough benefit from the tranny cooling to justify undoing the bypass(assuming the Denso is fail proof form SMOD)?

Also, I have never had any cooling problems prior to this... I will likely have the upper and lower hoses replaced since everything is exposed anyway, but is it advisable to replace the thermostat or leave it alone? And would you replace the belt eve if it looks good? Hoping the shop won't add a lot of cost for some other easy tasks since things are easy to get to with the shroud removed... anything else that I should seriously have then do since things will be exposed?


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AZhitman
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I'd keep the external trans cooler in place (if you have one)... I'm not a fan of simply deleting a cooling function because someone had a bad experience.

Nissan's plastic radiators aren't supposed to last beyond the warranty, but somehow people think they're a lifetime part. I wouldn't keep one past 60k miles, and I've replaced a LOT of Nissan radiators with aluminum ones.

An aluminum radiator should be plumbed to handle the ATF cooling duties, as they're not as prone to hidden failure as a Nissan one.

Mike W.
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You might want to think about a water pump and maybe fan clutch if you're in that far. Depending on their age/mileage of course.

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VStar650CL
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2004 Nissan Altima 2.5 S

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AZhitman wrote:
Tue Aug 30, 2022 6:15 pm
Nissan's plastic radiators aren't supposed to last beyond the warranty, but somehow people think they're a lifetime part. I wouldn't keep one past 60k miles, and I've replaced a LOT of Nissan radiators with aluminum ones.
You must just have a lot of bad luck with plastic. The radiator in my '04 and '13 Alties are both original and never had an issue, and we don't see many failures in quality aftermarket ones either (TYC, Four Seasons, etc). The tank failures we do see are largely from people dinging the radiator supports in fender-benders and not realizing the radiator is being twisted ka-ka.

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AZhitman
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Joined: Mon Apr 29, 2002 2:04 am
Car: 58 L210, 63 Bluebird RHD, 64 NL320, 65 SPL310, 66 411 RHD, 67 WRL411, 68 510 SR20, 75 280Z RB25, 77 620 SR20, 79 B310, 90 S13, 92 SE-R, 92 Silvia Qs, 98 S14.
Location: Surprise, Arizona
Contact:

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We get the telltale "black-to-brown" or "black-to-green" tank discoloration (which you're familiar with) here in AZ quite quickly. My Titan did it at 60k, and our Frontier did it at 70k.

I suspect it's heat-related, considering underhood temps can exceed 200F and temp differentials at street level can be less than 50* (ambient air vs coolant).


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