CVT temp went way high...

[phmichel]

From our Rogue Forum a couple days ago:

VStar650CL post_id=6849586 time=1690942496 user_id=299034]


I'm going to take the cooler I removed from the Rogue and install it on our 2017 Quest since it doesn't have the bypass valve (the Quest runs pretty hot). I intend to cut the fluid return line from the radiator and route it through a cooler mounted to the front of the AC condenser, then back to the beehive return. Can you help me with 2 questions per the diagram below?
1. Which hose is the return line - 21631 or 21631+B?
2. Which side is the primary fan?
Sorry to extend this Vstar and I am grateful for your help.

Admin - Please move this to the Quest forum if needed...

Vstar (or anyone concerned)- before I could get a chance to install the external cooler on the Quest, we took it on a 200 mile road trip over the Cascades in Oregon. It actually did OK on the mountain - hit 194F for about 5 mins climbing a 6% grade for 5 miles once, then ran between 165 and 180 mostly.
- BUT -
On the way back we were unexpectedly stuck in a crawl due to a wreck. Ambient temp 85F. Had no way off the freeway and after about 30mins at idle and crawl, the CVT hit 225F and went to limp mode. I heard a "clunk" and it shut the engine off. Sat for 10 secs, restarted and it was not in limp mode anymore but CVT was 226F and the engine was at 214F (both in red in CVTz50). Pulled off the road, opened the hood and sat for about 25 mins and watched it cool down to about 198F. Traffic was moving then so drove the 50 miles home normally and it cooled back down to 180 at hwy speeds. When I got home there were no CVT or Engine codes recorded. Should I be concerned?

[VStar650CL]

It's not good for it, but it probably didn't do any real damage at low speed and sitting in traffic. Under those circumstances most of the excess heat is being generated in the torque converter and there isn't much load to damage the belt. I'd get a fluid change right away, because I'm sure it did damage the fluid quality. Other than that, you're probably okay.

The real problem is Nissan's design of the cooling system controls. The ECM only runs the fan according to engine temperature and doesn't consider the temperature of the CVT. So in stop-and-go or prolonged idling, you can end up with the fan running at speeds that keep the engine happy but allow the waste heat from the TC and engine block to cook the transmission. Even a cooler does limited good, because the real problem is lack of airflow. I don't know of any good work-around, because the way Nissan multiplexes relays in their 3-speed fans makes overriding the IPDM impractical. Fooling the ECM by artificially raising the temperature reading won't work either, because unless it's very precise it will cause overheat codes. I've actually been trying to come up with something, because one of my CVTsaver customers (also with a Quest) had his temperatures hit the 190's while idling at an airport and was concerned that the CVTsaver wasn't working right. I had to explain that is was, but there are circumstances where the fan controls are problematic. The only thing I can suggest right now is giving the transmission its own pusher fan mounted to the trans cooler, tripped by a temperature switch embedded in the beehive outlet line. That isn't rocket science, but getting it fitted up could be a bit of a project.

[phmichel]

UPDATE:
Installed a Hayden 678 cooler. Attached to condenser. Hose routing was a real challenge but found a hole just big enough to run both of 11/32 hoses through. Wrapped with old heater hose where needed. Man, space is tight in that engine bay.

Ran it for 40 mins at 90F ambient. Didn't go past 155F. Idled in Drive for 10 mins and CVT temp did not rise at all (AC on and fans running). I'll do a D&F soon as I can but I hope this gives me another 100k out of this thing. Thanks for your help VStar...



That middle red arrow is the factory CVT fluid return from the radiator to the beehive, I just removed that connection, routed it to the cooler in, then brought the cooler out hose back to the factory return hose through a 5/16 brass coupler

[macgiver]

Supposedly the fluids are to "push-up from the BOTTOM , & out the TOP ?? (air....bubbles ya know ? Also fluid settles DOWN during lengthy shutdowns and keeps a better 'prime' ?) , great looking work , routing et all . Also , they don't come out of the box looking like that ? , I mean I would def. opt for a used or JY part - very simple part ya . The better price vs 'brand new' ....way worth it.
What took my eye to , was the lower Rt. half oil-stained , unless fluid simply spilled there during your FINE installation

[phmichel]

Supposedly the fluids are to "push-up from the BOTTOM , & out the TOP ?? (air....bubbles ya know ? Also fluid settles DOWN and keeps a better 'prime' ?) , great looking work , routing et all . Also , they don't come out of the box looking like that? , I mean I would def. opt for a used or JY part - very simple part ya . The better price vs 'brand new' ....way worth it.
What took my eye to , was the lower Rt. half oil-stained , unless fluid simply spilled there during your FINE installation

Hey Mike. I'm learning about the bottom-up flow issue. I may change it it but I had to get this thing back on the road. The cooler came out of my Gen 1 Rogue after about 40k miles. I swapped the cooler in the Rogue for a Hayden unit with a thermostatic valve so it will run warmer in winter. Works great. I should have cleaned it off. I'm such a pig. I did not want to use a t-stat unit on the Quest because the beehive routes it through the radiator for winter warm up and a t-stat unit would cutoff the flow entirely during the warmup cycle. Thanks for your keen eye... :Paul

[macgiver]

Ah , you know , I was thinking - imagine you just flip it upside dowm , as connected !

BUT your flange will no longer be 'flush' w/condenser (radiator?) fins , a need'n some standoffs , mentioned IN CASE you don't want again to literally "mess" / messy fluid undoing the both clamps and all ?
So hoses will cross .....so what ,right ? Cut plastic / rubber hose etc. or grab your 'junk-box and make standoff BECAUSE it would be better to have MORE space, an 'air-gap' , between condenser and your new cooler necessetating 1 1/2" standoff ? Better cooling due to better flow between them ?? The air is'nt so much ALL forced to go through that condenser - air move out & around sides utilizing the gap spacing I talk about.
Liitle tricks 'o the trade here ......little tricks

[VStar650CL]

Yah, Mac is right about the routing. If it isn't too inconvenient, at some point you should swap the pressure and return hose locations so pressure enters from the bottom.

[macgiver]

Ya , I was trying to pop-in EARLY before he started so much re-installation as to increase difficulty of what would normally be a minor "re-work" .

[phmichel]

First off I hear you guys and it will be easy to swap the hoses on the cooler...
- BUT -
This cooler works TOO good on the Quest. We just finished a 250 mile trip (85F ambient) with some in heavy traffic and hills and ran around 150F. It hit 160F tops. That's great, but it took about 20 mins just to hit 122F which is the low-side threshold. This was at 85F so I would imagine this thing would never warm up at 35F.
So my secondary question is: Would it be ok to install a Hayden cooler with the thermostatic valve? The one in my Rogue works great but that is a parallel cooling circuit. The Quest is a series circuit that (I think) routes the fluid through the radiator for warming in winter. If I leave this as is, the CVT would never get warm in the winter, but I don't know if it would be ok to basically turn off the entire circuit until (or if) the cooler tstat opens the cooler? Your thoughts?

[VStar650CL]

The new type in the Rogue is still a bypass from what I can see. It doesn't block the flow of fluid through the system, just through the cooler fins. The reed valves simply make it bi-directional, they divert the flow and don't block it. So I don't see any reason it can't be used in series like any standard H-valve cooler.