External transmission radiator

[BRRC]

I'm thinking of installing an external transmission radiator . Has anybody done it before , any inputs , ideas ???

[VStar650CL]

You're talking about a radiating type transmission cooler, as opposed to the heat exchanger type embedded in the radiator (which your '11 Versa should already have). I'd recommend the same cooler installed on my wife's '13 Altima, a Hayden 697. It has a built-in 160F bypass valve (appropriate for both A/T's and CVT's) and doesn't care about flow direction, making for easy hookup. I also recommend leaving the heat exchanger in the loop unless you live in a tropical climate. Cold fluid causes excessive mechanical wear, and part of the heat exchanger's job is helping the fluid warm up in cold weather. However, if it's an A/T and not a CVT, you probably want to back-flush the heat exchanger while installing the cooler, to make sure it hasn't become clogged with clutch material.

[BRRC]

Thanks ,but how do you hookup the external with the one already at the bottom of the radiator ?

[VStar650CL]

You put them in series. The bypass valve will stop flow through the cooler when the fluid is below 160F but will still let it circulate through the exchanger and back to the transmission (that's why it's called a bypass). Once the fluid reaches 160F the bypass opens and fluid circulates through both the cooler and the exchanger. On most Nissans, because of the way the lines are arranged, it's easiest to route the existing pressure hose to the cooler inlet, then install a new hose from the cooler outlet to the exchanger inlet, than leave the return hose from the exchanger outlet to the transmission alone.