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RE4R01A transmission advice requested (reinstall old transmission or replace with remanufactured)

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So I'm doing the RMS repair and I'm in the process of pulling the transmission. Not wanting to do this again, I'm now debating whether to put the old transmission that is working back in, or go ahead and get a remanufactured transmission instead. It's a 2002 Pathfinder SE 2WD (RE4R01A 4eX79) with about 170k miles on it. Most of those miles were normal around town miles, so it hasn't had a hard life.

 

I've had bad experience with non-OEM Chinese made parts that I'm hesitant to put in a remanufactured transmission that is remanufactured with Chinese crap.

 

Anyone have wisdom to share on what you'd do, who would you buy a remanufactured transmission from, etc.?

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Describe everything you notice about how your transmission shifts and performs. For example, it shifts from 1st to 2nd with a quick bump and a quick bump down in RPM but 2nd to 3rd is slower and the RPMs float down, also it sometimes doesnt want to shift out of 4th gear on the interstate especially after a long incline, and most of the time it takes an abnormally long time to shift into reverse.

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On 8/18/2019 at 10:40 AM, onespiritbrain said:

Describe everything you notice about how your transmission shifts and performs. For example, it shifts from 1st to 2nd with a quick bump and a quick bump down in RPM but 2nd to 3rd is slower and the RPMs float down, also it sometimes doesnt want to shift out of 4th gear on the interstate especially after a long incline, and most of the time it takes an abnormally long time to shift into reverse.

Actually, it's really not having any problems, I just was curious if I should bite the bullet while it is out and replace it. I think I'm going to put a new filter strainer, put fresh fluid and use a transmission cooler bypassing the radiator but using a thermostat bypass.

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Bypassing the radiator is a good thing. You should definitely move forward with doing that. What’s this thermostat bypass you speak of?

My suggestion is to leave well enough alone in regard to rebuilding the trans. If you have a solid 4R01 and it’s being kept cool then you are golden. These transmissions get some flak, and some of it is rightful, but they are beefy and the good ones often go the distance.

I believe Nissans weak radiator cooler kills most of them. And honestly the cooler isn’t sized incorrectly or anything but as the radiator scales and becomes less and less efficient then the trans suffers foremost and is only rivaled by the cylinder heads.

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12 minutes ago, onespiritbrain said:

i believe Nissans weak radiator cooler kills most of them. And honestly the cooler isn’t sized incorrectly or anything but as the radiator scales and becomes less and less efficient then the trans suffers foremost and is only rivaled by the cylinder heads.


So, if one were to replace the radiator for whatever reason, it would make sense to bypass transmission lines then, or even go with a separate cooler at that point? I don't have any leaks on mine currently, but there are some suspect looking spots on the fins from a previous accident. I was thinking about replacing it at some point before it became a problem.

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If you bypass the radiator you must have something else in place for sure. If you’re replacing the radiator then you’ll have the trans lines off and it would indeed be a good time to install an aftermarket cooler in place of using the one integrated into the radiator.

 

 

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21 hours ago, onespiritbrain said:

Bypassing the radiator is a good thing. You should definitely move forward with doing that. What’s this thermostat bypass you speak of?

https://derale.com/product-footer/fluid-coolers/thermostats-1/fluid-control-thermostats

 

Video https://www.youtube.com/watch?v=yEJD9fR_skw

 

Of course I'd go with the 3/8 with 3/8 tube barbs.

 

Trying to figure out what size external cooler and how I'd mount it. I don't want to put it in front of the AC condenser.

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