2009 Pathfinder Radiator Bypass hose routing question?

Discussion topics related to the radiator and transmission failures in all Nissan trucks, education of the public on this issue, and attempts to force Nissan to start a recall.

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Martin
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Joined: Thu Sep 12, 2019 9:00 pm

2009 Pathfinder Radiator Bypass hose routing question?

Postby Martin » Thu Sep 12, 2019 9:25 pm

Hello,

I have just bought my first proper 4x4, a 2009 Pathfinder.

New to the forum and just came here to get a feel for what I need to know and as it turns out I really needed to know about the radiator issue so thank you!

However, I have taken the skid plate off to get access and I don't seem to be able to join the hoses as easily as others on the forum. I wanted to post a few photos and make sure I have understood the fix correctly.

Photo 1: My car with showing the smaller transmission cooler on the drivers side and normal radiator behind.

Photo 2: Drivers side view, the hose going from the Radiator to the oil cooler circled in red

Photo 3: In this photo I have circled in red the output hose from the transmission to the shared radiator in red and in yellow I have marked the return hose from the transmission oil cooler.

My question is that to bypass the radiator I have to get new hose as the current one does not reach, nobody else seems to have done this, have I miss understood?

Have I correctly understood the flow of transmission coolant?

Secondly, where do I check to make sure nobody has replaced this radiator and it is one of the problem ones.

Any insight fellow members can offer would be amazing. Really cant afford a dead transmission!!

Thank you so much.

Martin


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smj999smj
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Postby smj999smj » Thu Sep 12, 2019 11:24 pm

The first thing you need to know is that the procedure for 2005 through 2007 is different, and simpler, than that for 2008-2012 because the moved the location of the auxiliary trans cooler from the right side to the left (like on yours).

On 2008 and later, you'll need about 2' of 5/16" (or 8mm) transmission cooler hose, two 5/16" caps and some miniature hose clamps. Some also gets some Kooler Kleaner or brake cleaner to clear out the ATF in the cooler line before they install the 5/16" caps (with clamps) on the radiator's cooler line fittings.

In your #3 pic, the hoses are mislabeled. The hose circled in red is actually the return hose from the radiator to the transmission...and this hose is eliminated and the fitting is capped off. The hose you have circled in yellow is actually the hose going from the transmission to the auxiliary cooler...and this hose is left alone.

In your #2 pic, the hose you have circled in red is the cooler hose going from the auxiliary cooler to the radiator. If you follow the hose up a little, you can see a couple of clamps where there is a union in the hose. So, this hose is disconnected from the radiator fitting (which is capped off) and disconnected from the union. This hose is eliminated.

Now, the brand new cooler hose is connected and clamped to the union fitting, which is on the radiator's left side. The new cooler hose is now routed to the trans cooler metal line remaining on the right side of the vehicle, trimmed to the proper length and clamped. You can use a plastic tie strap or two to secure the hose in position, as needed.

Now, all you have to do is clean up the mess, start the engine and check the trans fluid level (top off, as needed...but, in most cases you won't) and then re-install the skid plate after confirming there are no leaks. Done.

So, to help you understand the flow path as it came from the factory, the ATF exits the transmission and goes to the auxiliary cooler. The ATF passes through the auxiliary cooler and goes to the left side of the vehicle where it follows a hose along the side of the radiator which connects to the left cooler fitting on the radiator. The ATF then flows through the integral trans cooler inside the bottom tank of the radiator and exits via the cooler line fitting on the right side of the radiator. It then goes back to the transmission where the ATF is dumped back into the trans pan.

As far as determining if your radiator has been replaced, the factory-installed, Calsonic radiators have a sticker with a part number at the very top of the radiator's top tank, on the left (or driver's side) of the radiator cap. There will be a 10-digit part number on the sticker, starting with "21460-." On the 2008's, you'll likely see part numbers 21460-EA265 or EA215 or 21460-9CA2E (if it was an early replacement). "NISSAN" will also be molded in the right side of the top radiator tank, although you have to look for it because it doesn't stand out. If you have a radiator with no sticker on the top tank, it is most likely an aftermarket replacement. If it has a Calsonic sticker with another number on it, it is likely a replacement, but it may or may not be a radiator that has been affected by the issue, which depends when it was installed. In that case, post the part number and I can help you further. If it is an aftermarket replacement or a Nissan "Value Line" replacement part, you should be in good shape as they have not been affected by the cooler failure issue.

Personally, my preference is to replace the radiator rather than bypass, but each method has its pros and cons.

Martin
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Joined: Thu Sep 12, 2019 9:00 pm

Postby Martin » Fri Sep 13, 2019 2:17 pm

Thank you SMJ for a detailed response, really appreciate it.

I checked the radiator and it matched the ones you mention below with the issues so bypass it is for now!

Typical, as soon as I clamped the old hose so I could do the bypass it split so I ended up replacing both the hose from the Transmission cooler back to the transmission.

I have linked a couple of photos for reference.
Photo A shows the hose changes from the drivers side of the car. Old hose disconnected and hanging there, new one routed across the car.

Photo B Shows the other end of the new hose coming from the drivers side and back into the transmission. You can also see the nipple from the shared radiator on its own.

The final thing I did to complete the job for now was to place radiator hose between the input and output of the shared radiator that was bypassed. This is because the shop this morning had no caps and I can get back in at a later date to flush fluid through it as for now it just drained.

I understand that unless I tow I do not have to worry about overheating. I do live in Canada though so in the winter I assume I just need to be very gentle with acceleration until the fluid has heated up, maybe ten minutes behind the water temperature gauge reaching normal?

Finally there is nothing in my owners manual about correct checking of the transmission fluid. I have read conflicting methods with both the engine running and off. Do you have a preferred method?

Thank you again for your help. I literally read the radiator issue over dinner last night and went straight down to the car to start this job!

Cheers,

Martin

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smj999smj
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Postby smj999smj » Fri Sep 13, 2019 6:25 pm

As far as driving it easy in the winter until the engine temperature has heated up, it doesn't make any difference (as far as the engine temperature) because the bypass eliminates the transmission fluid path being warmed-up by the engine coolant. So, the transmission fluid will heat up only due to the actual "goings on" inside of the transmission, while still being cooled via the auxiliary trans cooler.

Automatic transmission fluid should be at normal operating temperature when checking, so it's not a bad idea to do at least some driving before checking it. When checking the ATF, the engine should be running, on a level surface and with the transmission in "park" or "neutral."

Limey
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Re: 2009 Pathfinder Radiator Bypass hose routing question?

Postby Limey » Thu Jul 07, 2022 10:13 am

My 06/2009 build date PF has the 21460-ZL11A am I safe?

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VStar650CL
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Re: 2009 Pathfinder Radiator Bypass hose routing question?

Postby VStar650CL » Thu Jul 07, 2022 11:38 am

Limey wrote:
Thu Jul 07, 2022 10:13 am
My 06/2009 build date PF has the 21460-ZL11A am I safe?
Your ZL11A was the very last iteration before Nissan issued the 9CA0E, which was the "final solution" for the cooler problem. The vast majority of failures were in the '05~'06 models, but a few (very few, really) failures were still reported with the ZL11A's on the '09~'10's. So the answer is, you're probably okay, but not definitively.

Limey
Posts: 116
Joined: Fri Jun 17, 2022 5:17 am

Re: 2009 Pathfinder Radiator Bypass hose routing question?

Postby Limey » Wed Jul 13, 2022 6:15 am

VStar650CL wrote:
Thu Jul 07, 2022 11:38 am
Limey wrote:
Thu Jul 07, 2022 10:13 am
My 06/2009 build date PF has the 21460-ZL11A am I safe?
Your ZL11A was the very last iteration before Nissan issued the 9CA0E, which was the "final solution" for the cooler problem. The vast majority of failures were in the '05~'06 models, but a few (very few, really) failures were still reported with the ZL11A's on the '09~'10's. So the answer is, you're probably okay, but not definitively.
Thanks. That’ll always play in the back of my mind.


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