another trans/radiator bypass done

The Gas and Diesel Engines - VQ40De, VK56DE, YD25DDTi, V9X, Transmission, Transfer Case, Oil, Differentials, Axles, Exhaust...

Moderator: volvite

Cruzin1a
Posts: 17
Joined: Sun Sep 08, 2013 3:04 pm

Re: another trans/radiator bypass done

Postby Cruzin1a » Mon Nov 04, 2013 11:19 am

I just did my bypass the other day on our 08 PF SE, roughly 96k miles. I couldn't get the two hoses to join easily. I put another section of hose between the two using two barb connectors. I tried my best to keep the original hoses as close to their natural path as I could because I was afraid if I didn't they may kink. I then loosely zip tied it to what I think is the stabilizer. I can post a picture later. I've kept an eye on it now for about a week and there are no leaks. At this point I'll re-install the skid plate and be sure to remove it at each oil change to verify everything is tight.


doctahjones wrote:finally did mine, on a '08 5.6L, 81k miles. i was going to replace the radiator, but for now i'll just do the bypass. really didn't take too long, probably 10 minutes of actual work, but i did have to go back to the store to get another connector. originally i had gotten the 3/8th double barbed connector, but i couldn't really get it on -all- the way. maybe some of you can but i couldn't. plus the clamps i got were too small. so i had to go back and get the 5/16th double barbed connector


so, parts i used:

-2x 3/8ths rubber cap (get the 5/16ths if you can though, the 3/8ths is a hair too big)
-4x 5/16-? clamps
-1x 5/16 double barbed plastic connector

tools:
-10mm & 12mm sockets (you can use a large phillips head instead of the 10mm)
-pliers to unclamp the factory clamps
-plastic bottle to catch the few drips from the hoses
-big piece of cardboard to put under to catch anything you don't catch with the bottle
-nitrile gloves (optional)

i used some big clamps i have to try to pinch off the hoses going to the radiator. i guess they did their job since i only got maybe 1/4oz of fluid out.
Image


so what i did was pull one hose off the radiator (doesn't matter which one), throw the rubber cap on the radiator side (it might still drip a couple drips without the clamp on yet, but it's really just 1-2 drips, you're not going to flood the floor with fluid) and then drain the little bit of trans fluid in that hose into an empty water bottle, then put the new clamp and connector on that side of the the hose. then do the exact same for the other side. then tighten the clamps. i also then uncapped both sides of the radiator, put a bottle on one side and put an air compressor on the other to blow out anything that was left. there was barely anything in there.

all done:
Image


i didn't zip tie it or anything, doesn't seem like it gets in the way/touches anything.



also, so i've never changed my own oil in the pathfinder (always had awesome deals back in texas just to have it done, $20 for reg and like $70 for mobil1), so when i changed it myself when i did the bypass i noticed this nifty little piece of metal under the oil filter that keeps the dripping (mostly) off the frame and sway bar:
Image


User avatar
akley88
Posts: 449
Joined: Sun Mar 03, 2013 1:45 pm
Location: United States

Postby akley88 » Wed Nov 27, 2013 5:20 am

i just did mine the other day on my 08. except i just replaced the line going on the passenger side that went into the radiator with a longer hose so i would only have 1 connection between the two sides. no issues besides a cooler trans. i also didnt lose more then 1 or 2 oz of fluid cause i did the bypass after the car had sat in my slightly sloped driveway over night.

User avatar
eieio
Sponsored Member
Posts: 1830
Joined: Fri Jul 17, 2009 6:42 am
Location: Prescott, Az.

Postby eieio » Wed Nov 27, 2013 7:08 am

akley88 wrote:no issues besides a cooler trans.
:? how so?

User avatar
akley88
Posts: 449
Joined: Sun Mar 03, 2013 1:45 pm
Location: United States

Postby akley88 » Thu Nov 28, 2013 9:15 am

eieio wrote:
akley88 wrote:no issues besides a cooler trans.
:? how so?
Maybe I should say a cooler running temp cause the temp stays at 147-155 before it would be 165-180

De Maria
Posts: 5
Joined: Tue Dec 15, 2015 9:49 pm

2008 Pathfinder bypass radiator

Postby De Maria » Tue Dec 15, 2015 9:55 pm

It looks like its been a couple of years since the last message on this thread.

I'm getting ready to do the bypass on my 2008 Pathfinder, but the mechanics I've consulted tell me its a bad idea. I can't see anything bad about it. But I was wondering if there was any follow-up info from folks who had done this. Whether there were any unforeseen side effects?

User avatar
disallow
Site Admin
Posts: 2806
Joined: Wed Aug 13, 2008 9:02 am
Location: Winnipeg, Canada

Postby disallow » Tue Dec 15, 2015 9:58 pm

Just the foreseen side effect of no SMOD. :)

I ran bypassed in my 05 for 4 years. Recently replaced my rad so I hooked everything back up, but seriously considered leaving the bypass in place as there was literally no down side.

User avatar
smj999smj
Site Admin
Posts: 5751
Joined: Sun Jan 22, 2012 11:13 pm
Location: Prospect, VA

Postby smj999smj » Wed Dec 16, 2015 1:52 am

Well, the downside is that you do lose some potential cooling it the fluid were to get hot under adverse conditions and you lose the warming affect of the coolant to maintain the ATF in the ideal operating range as well as the ability to quickly warm the ATF up to normal operating temperature, especially in very cold weather.

De Maria
Posts: 5
Joined: Tue Dec 15, 2015 9:49 pm

Postby De Maria » Wed Dec 16, 2015 5:52 pm

disallow wrote:Just the foreseen side effect of no SMOD. :)

I ran bypassed in my 05 for 4 years. Recently replaced my rad so I hooked everything back up, but seriously considered leaving the bypass in place as there was literally no down side.
Thanks for the info. I don't see a down side either. But you never know. Its good to hear from someone who did it. I'll probably do it as soon as I get a few days off.

De Maria
Posts: 5
Joined: Tue Dec 15, 2015 9:49 pm

Postby De Maria » Wed Dec 16, 2015 6:13 pm

smj999smj wrote:Well, the downside is that you do lose some potential cooling it the fluid were to get hot under adverse conditions and you lose the warming affect of the coolant to maintain the ATF in the ideal operating range as well as the ability to quickly warm the ATF up to normal operating temperature, especially in very cold weather.
1. Did you do the bypass?

2. Because here's my theory.

It doesn't make sense to me that the ATF would warm up quicker with the stock system since its going through two cooling systems.

First the ATF runs through the radiator. The radiator is a cooling system. The coolant in the radiator is specifically made so that it sucks up heat. Thus, it will cool off the ATF.

Then it flows through a transmission cooler and is cooled off even more.

Therefore, if I reroute the ATF so that it avoids one of the cooling systems, it should run a bit hotter.

3. Unless your telling me that the radiator heats up the transmission fluid. Which then means that if I'm towing, I really don't want my transmission fluid flowing through the radiator, because it would cause it to heat up even more.

Anyway, that's my thoughts.

User avatar
smj999smj
Site Admin
Posts: 5751
Joined: Sun Jan 22, 2012 11:13 pm
Location: Prospect, VA

Postby smj999smj » Thu Dec 17, 2015 2:30 pm

The first radiator I did was on my 2006 several years ago. On that one, I replaced the radiator. The second one was on my 2008, which I bypassed, initially, but recently went back and replaced the radiator and re-connected the cooler lines. It wasn't so much that I had an issue with the bypass on the 08, but I got a really good deal on a Koyo radiator for $50 and decided to replace it.

You have the order of the trans cooler system incorrect. The ATF goes through the auxiliary cooler first, then routes through the radiator's integral cooler and back to the transmission. The auxiliary cooler is exactly that: a cooler. The radiator's integral cooler is both a cooler and a warmer and is designed to maintain the transmission fluid within a specific range. Automatic transmission fluid should normally run in the 175-200 degree F range in the transmission oil pan and shouldn't run any cooler than 150 degrees F. With just an air-to-air cooler, or coolers, installed, the temperature could fall below that temperature, especially in very cold weather, which is not ideal for the transmission. Using an air-to-water cooler, like the one inside the radiator lower tank, allows the heat of the coolant to get the temperature of the transmission fluid up to the 150+ degree F range more quickly and allows the ATF to be maintained in the 175-200 degree F range, which is optimal for ATF. This is the reason they route the ATF through the auxiliary cooler, first, then the radiator cooler; even if the ATF is over-cooled when it exits the auxiliary cooler, it will be warmed up and exit the radiator cooler at the optimal temperature. This is also why most vehicles use just the air-to-water cooler from the factory rather than just an air-to-air cooler. Now, if the ATF, as it exits the auxiliary cooler, is too hot (which would be a rare case that would likely only occur under extreme towing conditions), the radiator's cooler would then serve as a cooler to the ATF and air-to-water coolers are far more efficient than air-to-air coolers.

If you are interested, here's a good guide for transmission fluid temperatures:

http://www.digi-panel.com/trannyoil.htm

De Maria
Posts: 5
Joined: Tue Dec 15, 2015 9:49 pm

Postby De Maria » Thu Dec 17, 2015 4:03 pm

smj999smj wrote:The first radiator I did was on my 2006 several years ago. On that one, I replaced the radiator. The second one was on my 2008, which I bypassed, initially, but recently went back and replaced the radiator and re-connected the cooler lines. It wasn't so much that I had an issue with the bypass on the 08, but I got a really good deal on a Koyo radiator for $50 and decided to replace it....</b>

THAT is very informative and helpful. Thanks!

But especially the $50 Koyo radiator. If I could get one that price, I would also prefer to keep the designed system.

User avatar
smj999smj
Site Admin
Posts: 5751
Joined: Sun Jan 22, 2012 11:13 pm
Location: Prospect, VA

Postby smj999smj » Thu Dec 17, 2015 11:33 pm

Yeah, a former member on these forums sold his Pathy and had it sitting in the box in the Philly area. I just happened to be making a trip to NJ, so it was just a little side trip out of the way. He had some other stuff I picked up, too. I couldn't argue with the price.
The radiator I purchased three years ago for the 06 was a Chinese-made (most radiators are made in China, these days...even the name brands) Ebay unit I got for $92 (last I check, you can get them for around $75) and it's worked out great, so far (knock on wood).

De Maria
Posts: 5
Joined: Tue Dec 15, 2015 9:49 pm

Postby De Maria » Wed Dec 23, 2015 11:41 am

smj999smj wrote:Yeah, a former member on these forums sold his Pathy and had it sitting in the box in the Philly area. I just happened to be making a trip to NJ, so it was just a little side trip out of the way. He had some other stuff I picked up, too. I couldn't argue with the price.
The radiator I purchased three years ago for the 06 was a Chinese-made (most radiators are made in China, these days...even the name brands) Ebay unit I got for $92 (last I check, you can get them for around $75) and it's worked out great, so far (knock on wood).
Thanks. I'll look into that.

jeff91c2t
Posts: 2
Joined: Tue Dec 12, 2017 9:13 am
Location: central coast

Re: another trans/radiator bypass done

Postby jeff91c2t » Sun Jun 28, 2020 4:06 pm

Thought I'd add a first hand experience regarding the radiator bypass (I've been running this for the past 4 years/30k miles). There is often conversation about trans temps so thought I'd share this story on the hot-extreme side.

Did a big trip this past weekend and on section 2 of the WABDR there was a hard long (20+ minutes) slow (1st gear) climb up a rough gravel section. Outside temp was ~88 degrees. Almost to the top I got the yellow 4x4 warning light and a check engine light (read the code and it was U1000). After the 4x4 light came on a couple of minutes later no forward gears would engage. Give it throttle in drive and the motor would just rev. Nothing...I was sure I just lost the trany and in the middle of friggen nowhere! Interestingly it would still go into reverse.

I let it cool for 5 minutes and cleared the fault and had forward gears again. Since we were only a few minutes from the top we made it with out issues. Trans felt/feels the same after. Check the fluid level, color and smell and no issues. This happen one other time on another tough 2nd gear/hot climb where I got the yellow 4x4 light. That time I picked up the speed and dropped from second to first to get the rpm's up. We could see the top so I had nothing to loose...except the trans of course ;-) Made it over and no more issues on the rest of the 300 miles to get home...

Unfortunately I was not recording trans temp and the U1000 code is useless (need to run the 4x4 check apparently...). My thoughts are ECU went into protect mode with the heat and disengaged the transmission. I hope anyway... This little indecent rattled my cage for sure, I'm putting in a new all aluminum radiator and will get rid of the bypass.

If there's a recommendation for radiators post up!

User avatar
smj999smj
Site Admin
Posts: 5751
Joined: Sun Jan 22, 2012 11:13 pm
Location: Prospect, VA

Re: another trans/radiator bypass done

Postby smj999smj » Sun Jun 28, 2020 7:55 pm

The U1000 is a CAN communication code, so I wonder if the fluid in the pan got so hot that it affected the TCM on the valve body which triggered the code? Just a thought... You really don't "need" an all-aluminum radiator as the plastic-tanked radiators will work fine, however, I understand the want to upgrade; at least you don't have to worry about the plastic tank getting brittle and cracking many years down the road. The issue is that the all-aluminum radiators can get expensive. Stillen, Offroad Gorilla and some others sold the CSF all-aluminum radiator for $350 but later stopped selling it because of problems with them. Griffin is a good choice if you don't mind the high cost:

https://www.griffinrad.com/load_details ... =NIS-70002

Summit Racing sells it for $753 with shipping. It's Griffin P/N: NIS-70002. I know the CSF radiators came with vented-type radiator cap (has the spring on the bottom of it), which is incorrect, so that is one thing to check if you get an all-aluminum radiator.


Return to “R51 Engine, Driveline and Powertrain”

cron