The Nissan Path

OK, I live in a cold climate, Manitoba. My tranny guys wants me to install a new aftermarket Rad instead of bypassing the existing and mounting a separate cooler. He says that during the winter I may have issues with the transmission oil being to cold and that will result in other issues. Thoughts?

I agree with him. The trans cooler in the radiator is not only designed to cool the fluid, but also to warm it and help maintain proper operating temperature. Ideally, ATF should operate around 175 degrees F. In a cold climate such as yours, I can completely understand his concerns. Most R51's come with an auxilary cooler, anyway; you should be able to open your hood, look down in front of the AC condensor and see it mounted on the passenger side if you have one. Personally, I purchased a new, aftermarket radiator for $92 US on Ebay with a lifetime warranty. Yeah, it was made in China, but fit perfectly and is working fine.

I'm near Niverville, and run my 05 bypassed, and don't have any extra cooling installed.

The first couple shifts in -35C are a little more pronounced, but I don't see it as a major issue.

My truck has 200k kms on it, and is still going strong. As you can see in my avatar, I also regularly tow a humungous camper with it.

In my opinion, I'd just do the bypass. If you need the extra peace of mind, get another cooler installed. Better yet, get a tranny temp gauge installed, so you know if you are actually overheating.

t

I had a very good technical discussion with the service guys at the dealer this morning. Their opinion was that is is NOT advisable to bypass the rad. The external cooler is first in the circuit, then the rad loop. The rad actually does the bulk of the cooling because it is far more efficient at doing so.

In addition, it serves to warm the trans fluid if it is cold, preventing both uncomfortable operation and potential damage.

The goal is to stabilize the trans fluid within a fairly tight temperature range, which the rad system does very well.

If you are concerned with the rad failure and you are within the extended warranty period, they suggest that you have inspections done frequently as you approach the warranty limit, and resolve the rad failure while under warranty should it appear.

If you are past the warranty limit, they suggest installing an aftermarket rad (the Koyo one seems to be the fav). That is not terribly difficult, and let's be honest - in a month you probably drink and smoke more $ than it would cost!

I am 11000 km over the extended warranty, and we are discussing with Nissan Canada whether they will approve a warranty fix.

Sorry you are having problems. Note that if you had been bypassed, you wouldn't be facing the transmission problems you are having now.

I do not agree with the Nissan Techs at all. I work for a heavy vehicle manufacturer, and am involved in many technical aspects of cooling package design, testing and sourcing.

Although your statement is correct in regards to the efficiency of water/oil vs air/oil, you also have to think of the deltas:

Water = 180F to 200F vs Oil ~ 250F

OR

Air = -40F to 120F vs Oil ~ 250F

The temperature delta of Air/Oil is greater than that of the Water/Oil. There may be something to the 'heating up' effect you mention, but I'd put forward that when its -40, your rad is stone cold too. I think the transmission would heat up a whole lot faster than the radiator when driving. Maybe the transmission helps heat up the engine?

We have also had several members install transmission temp gauges to monitor the different conditions between standard setup, bypassed radiator, and bypassed radiator with external fan. In most operating conditions, the bypass did not seem to really affect trans fluid temps. I have a temp gauge sitting in my shop, just haven't had a chance to get it installed yet.

Ultimately, I will probably change my radiator. But until then, I will run bypassed. Have been doing so for 3 years now, put on over 110k kms, tow a humungous camper regularly, and have had no issues at all. Proof is in the pudding!

t

U P D A T E:

Nissan is replacing the rad and the trans under warranty. I am a very happy dude.

Thank you to all the posters here who informed my discussions with Nissan!

Sorry to hijack this thread but Disallow, what's the specs on that beastly trailer you tow? Looks simply huge.

We should bet on the size, I guess 26ft.

RacerZX wrote:Sorry to hijack this thread bot Disallow, what's the specs on that beastly trailer you tow? Looks simply huge.

Its a 28 footer. Keystone Passport 280BH.

4600lbs dry, ~5500lb loaded.

Dang, would have lost the bet.

Hunh, I would have thought it was heavier from the size, cool thanks.

Here is a link to the specs:

http://www.rvguide.com/specs/keystone/t ... 280bh.html

Trailer manufacturers are notorious for understating the dry weight of their vehicles. However, in the reading I've done, it seems Keystone usually does a good job.

Areas to watch are if the appliances or add-ons are included in the UVW or not. AC units, 3-way refrigerators, stoves, ovens, propane tanks, spare tires, etc etc.

The Max GVW on this unit is 6050lbs. So it actually has a pretty limited payload of 1470lbs. But it does keep the overall weight down.

I find the biggest challenge is the wind. If there is a really strong wind, the trailer is so long that it actually does the whole 'tail wagging the dog' thing and can make for a pretty white-knuckled experience...

t

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I just bought a new to me 2007 Pathfinder and have read to the problems that could be caused by the radiator.

I want to make sure my happy little Path stays that way.

I do have a suspect part on my truck, so I know it has to go or be bypassed. The bypass takes about $15 in parts, but I can also replace the rad for about $100 - $540 depending on where I source the part from.

Does anyone know what the best/most recommned replacement rad is or if their are certain aftermarket rads I should avoid if I choose to go that route. All of the after market rads I have found also have plastic tanks and I would guess could experience the same failure or maybe even made by Calsonic and just rebadged.

Any info would be great. I would like to keep my tranny happy and coolant free for another 85000 miles.

Thanks,

Chris
2007 Nissan Pathfinder SE

Sorry double and triple post

I'll just say thanks for any help in advance