I suspect there's something wrong with the installation.

VStar650CL wrote: ↑

Sat Jul 16, 2022 5:31 am

Steep hills and heat combined will definitely do it. The CVT heat exchangers work great as long as the engine cooling system isn't working too hard, but when it is, the radiator outlet tank temperature rises and the CVT loses its best friend. That's when an add-on radiating cooler will save your tranny's life. The only time the one on our Altie ever kicks in is climbing Mount Petit Jean or Mount Nebo in the heat of summer, but I can watch the H-valve open like clockwork about 3/4 of the way up. The roads up the Sierras are way longer than those climbs.

VStar650CL wrote: ↑

Wed Jul 20, 2022 4:39 pm

Taking the heat exchanger out of the loop and just using aftermarket is no big deal, if that's what you're asking. That's basically what Nissan did with the gen1 Rogues and early Altimas/Sentras that had no cooling at all. However, that was basically a stopgap, so you should be aware of a couple things. First, one advantage of the heat exchanger over a radiating cooler is that it works even when the car isn't moving, whereas a radiating cooler is entirely dependent on the fan when you're stopped in traffic. The ECM isn't looking at CVT temperature when it decides how fast the fan should run, so that can put the two systems in conflict. Second, if you do dump the heat exchanger, dump the H-valve too and simply install a big radiating unit. I think that's probably fine for you in a hot climate with mostly highway driving, and going oversize on the cooler will counteract the fan-dependency problem to some degree. Anyway, to do that simply requires disconnecting the heat exchanger and routing the two nipples on the beehive directly to the radiating cooler.

I've actually been putting some thought and experiment into this (we're having routine 100F's here in Arkansas lately too), and I think I may know why your Quest in the Sierras is heating up so much worse than my wife's Altie on Mount Nebo. I think it's an airflow problem arising from the very front-to-back-compressed engine compartment on Quests. The cooling loop for the trans won't be directly affected, but the indirect affect on the outlet tank of the radiator seems to be very large. On 100F+ afternoon today, I IR-checked the outlet temp on an R52 Pathy (also very crowded front-to back) versus a Maxima (somewhat more stretched) versus a gen5 Altima (very uncrowded 4-cyl) after running each several times up a steep incline at WOT. I found an enormous difference between the three, with the Pathy's outlet tank running a full 15F warmer than the Max, but the Max running only about 5F hotter than the Altie. With all the hardware crammed-in over the top of the tranny, that can't be good for dumping excess heat into the passing air, either. Now I'm wondering if "engine squish" isn't responsible for D1Dad's Rogue running hot on a long trip too. So I think I'm about to change my advice for coolers on heavily-squashed CVT vehicles like yours, or any SUV or cross. Unless you live in a cold climate, skip the H-valve. The over-cooling in winter will be far less destructive than the overheating in summer.