pre-2012 Sentra M6 CVT Behive operation

[tedthayer]

Nissan M6 Transmission Cooler ("Beehive")
I'm stuck, need some information ...

The pre-2013 Nissan Sentra CVT Transmission has a history of over-heating when climbing hills in the desert southwest in the Summer. There is an after-market kit for post-2012 CVT equipped Sentras that replaces the Beehive with a version that sends the transmission fluid through an add-on external radiator. Apparently, it works, but before I change mine, I need to understand how the Beehive works.

Here's what I know:
Engine water from the radiator is sent through the Beehive to keep the transmission warm ... not cool. Whatever the radiator coolant temperature is, that's what the transmission fluid/oil is warmed up to. In the southwest deserts when it's over 90 degrees or so, the transmission wants to overheat under high-speed loads. If it gets too hot, because the radiator coolant isn't dissipating the added heat, the ECU will put the vehicle in "Limp Mode" in which engine speed may be limited to 2,000 rpm and highway speed to 45 mph or less. It's not a bad feature if you can get to a place where you and the car can chill for a while! Adding an aftermarket "Beehive" CVT Transmission Cooler is probably a good idea ... I'm told that it works! As long as there is no adapter required.

What I don't know:
The Beehive is very tightly bolted to a mounting flange in the transmission with a 3-1/2 inch O-ring holding the surface a tiny fraction of an inch away from the transmission fluid/oil in/out port and filter mechanism. on the Beehive plate are two 1/2 inch hols that allow the fluid to flow into the Beehive separate from the engine coolant. I don't understand what creates the pressure gradient that causes the fluid to detour through the Beehive. Two identical holes on a flat surface has both the incoming and outgoing fluid in essentially the same plane. The only thing impeding the flow is the filter, but its outer surface and the plate containing the Beehive holes are effectively on the same plane, and one would think at roughly equal pressures because the plate is all that secures the filter in its housing..

The challenge:
To mount the after-market Beehive cooler (which has two pipes for engine coolant and two separate pipes for transmission fluid) requires an adapter, which I'll have to fabricate so differing mounting bolt configurations can be accommodated along with an appendage to hold the filter in place. The adapter will be made of strong 1/4-inch steel that will use the same O-ring configuration as the Beehive to seal it to the transmission. The after-market unit will mount the very same way (compressed O-ring) with a slightly different bolt configuration). I'm not confident that an additional quarter-inch of space between the Beehive mounting plate and the transmission will "go with the flow!"

Worst-comes-to-worst, I can modify the after-market Beehive to fit directly ... but THAT would be a BIG deal - and expensive! Is there some sort of internal mechanism in the Beehive that pumps the transmission fluid through it? Or What?
Now you know the rest of the story - or NOT!

[VStar650CL]

You're right that the beehive is a warmer and not a cooler, but you can get "4-port" beehives which allow adding an external radiating cooler or (if your radiator supports it) a heat exchanger. Yours should be the same one that fits the Juke, 21606-1XF0A. Once you install that you have external access to the fluid and can add any kind of cooler you like. If you live in a warm climate an open cooler like a Hayden 512 is appropriate, if you live someplace with four actual seasons then a 697 is a better choice (the 69x series has a 160F bypass).

[tedthayer]

Unfortunately transmission is a 2011 M6 and they don't make an aftermarket unit for that transmission. I'm a good enough engineer that I can make an adapter plate that will work on the available unit. I'm just not sure what an extra .250 inch (instead of the stock .025) will do to the flow in and out of the external cooler. Any Clues?

[VStar650CL]

I'm not sure what you mean by "M6", that generally designates the RS6F94R manual trans and not the CVT. The Sentra CVT's in '11 were RE0F10A's for both the MR20 and QR25 engines. The Jatco model number is JF011E. The version used in the Sentra and Juke differs from the one in the Rogue and Altima in having a "squeezed" final drive to accommodate the narrower engine box, but the aftermarket beehives should fit it just fine. I don't see why an adaptor plate underneath the 2-port wouldn't work fine too, but it's reinventing a $50 wheel.

[VStar650CL]

PS - Diverting the flow with an adaptor plate will pretty much prevent the beehive from warming, but if you live in a warm climate or use a cooler with a bypass valve it should be fine. If you want the beehive to still work I think the adaptor needs to make it into a 5-port, with the 5th port being internal for the return. I dunno if 1/4" will suffice, it probably needs to be thicker.

[tedthayer]

The aftermarket Behive delivered simply doesn't fit on the CVT in my Sentra. I have a drawing of an adapter plate that accommodates it with six screw mounts: two low for the New device, two low for adapter and two upper combined for both the adapter and the new Behive. The question at hand relates to the flow rate through the Behive "warmer" and the external "cooler". The stock mount allows flow through a "pool" of about .019 cu inches; with an adapter plate that "pool" increases to around 2.9 cu inches. It's true that we're dealing with hydraulic pressure (which should remain constant) but splitting the flow to one close by and another at some length could seriously degrade the effectiveness of the combined devices. Any ideas?

[VStar650CL]

Flow from the pump is generally only about 15 psi provided there are no major restrictions. In any case it's low pressure.

[VStar650CL]

Just out of curiosity, is the hive they sent you squared or cylindrical? If it's squared then they shipped you the wrong part.