Adding An External Cooler Can Add Years To Your Transmission

Oil coolers for engines or transmissions come in a myriad of shapes, sizes, and configurations. When it comes to coolers, they’re much like radiators: You really do get what you pay for. But no matter what type of cooler you have for your application, you still need to mount it. Many incorporate some sort of flange used to expedite mounting. Or at least that’s what it seems like from the onset.

However, we’ve all seen examples where some sort of plastic or nylon spear, complete with a big washer through the radiator core, affixes the cooler and you call it a day. Sure those setups work, but we believe there has to be a better solution for oil cooler installation.

In our case, the cooler in question is an Earl’s Temp-A-Cure stacked plate unit. It’s a quality piece, but it’s also an older superseded model (with different part numbers). The cooler is big. It measures 6-1/2 by 13 inches, and we selected a set of mounts to go with it. But those mounts only work for flat surfaces, and only for specific dimensions. The truth of the matter is, some fabrication work is required in order to mount it, and you’ll find that most likely applies to just about any cooler you choose.

oil cooler

We planned to use the optional mounting kit from Earl’s. This provides a surface to mount the cooler. It also provides a certain amount of vibration protection by way of rubber insulators.

Cooler Orientation 

It’s possible to mount the cooler with the ports at the top, on the side, or at the bottom.  But in terms of preference, top mounting is the best, followed by side mounting. With ports situated at the bottom, the cooler can trap air and that tends to be troublesome.

When it comes to coolers, which port is “in” and which port is “out”?  With a side-mounted oil cooler installation, the preference is to orient the “in” port on the bottom.  If you’re using the cooler for an automatic transmission application, which of the cooler line fittings on the transmission is “out”?  For a Turbo or Powerglide, the bottom fluid line on the transmission case is out.  The inlet is the top line.

oil cooler

The best cooler mounting is upright such as this. The cooler is covered in light card stock to protect it while it is positioned in various locations on the rad support. Unfortunately, there’s no room to access the fittings with this vertical layout.

Test Fit The Cooler 

With that out of the way, it’s now possible to dummy up different cooler locations. When selecting a spot for your cooler, you have to keep in mind air must pass through it. As a result, you can’t mount it flat under the car, an inner fender panel, or behind a bumper. Typically, good spots are directly in front of the radiator.  In some cases, it’s possible to block part of the cooler with a bumper or other hardware, but that occurs with radiators too.

In our case, we were working on a Nova and we thought we found a good spot to mount the cooler vertically (ports on top). But, after trying it in several locations across the face of the radiator, it became painfully obvious that it wasn’t possible to access the fittings – they’d end up jammed up underneath the radiator support. This meant the cooler must be side-mounted. As it turns out, one end of the cooler could actually bolt to the rad support, but that leaves the other side hanging in the breeze. The good news is, many vintage Chevys have a hood latch support that is more or less centered in front of the radiator. With careful positioning, it’s possible to use a fabricated “L” shaped bracket to attach the cooler mount to the hood latch support.

oil cooler

The second-best mounting layout for an oil cooler installation is positioned on its side.

Plumbing The Works

Plumbing is another issue with oil cooler installation. We picked Earl’s Perform-O-Flex AN hose for the application. It’s easy enough to use, but there are a couple of things we should point out. The fitting threads on the transmission case (Turbo 400) are NPSM threads. NPSM is similar to a common NPT thread, except NPT threads are tapered. NPSM threads are straight. The 1/4-18 NPSM thread to the -6 AN adapter fitting incorporates a nylon washer for sealing.  ATI Performance Products offers a number of fittings designed to adapt AN fittings to a transmission case. The -6 AN fittings we used are part number 925137.

A piece of aluminum angle makes a good bracket. Drilling holes in the bracket adds to the appearance. On the right is the finished bracket. If you place a sheet of 220 grit sandpaper on a flat surface and draw the bracket over it several times, the finish takes on a pretty neat brushed look.

We won’t show you how to attach hose ends (that’s another story), but when routing cooler lines in a modified Chevy, there aren’t a lot of options. The factory-formed steel transmission lines typically run from the transmission case, under the starter, and alongside the oil pan. They pass under the passenger side motor mount, along the engine side of the mechanical fuel pump, and then forward to the radiator. As it turns out, the very best plumbing path is the original layout. But remember, AN hose is larger in diameter when compared to factory-formed steel lines. With a modified application, headers take up room as well (in some cases, a lot of room). Take that into consideration when routing the cooler lines. You really don’t want to excessively bake the fluid as it is returning from the cooler.

oil cooler

Here’s the bracket attached to the Earl’s cooler mount as well as to the hood latch support. Why not mount the top bolts further apart? Simple. There is nothing to drill through because the hood latch support slopes away from perpendicular

When figuring out the routing of the lines, the first thing to do is dummy up the hoses and fittings required for the application.  Keep in mind, bent tube AN fittings aren’t the smallest items in the world. Neither is the bend radius mandated by straight hose end/hose combinations, particularly in larger sizes. Nonetheless, either use a partial hose/hose end combination installed on each of the cooler inlet and outlet ports when you simulate the installation. In this situation, we determined how to snake the cooler lines into place, then we marked the ends for fitting installation. Locations for clamping/supporting hoses are important too. It takes a bit of time to determine the hose routing and to figure out the required length.

ATI adapter fittings install on the transmission case and a Made 4 You clamp affixes the hoses to the subframe cradle.

While installing an oil cooler does take some time and planning, it isn’t difficult. if you want a clean setup, book yourself for more than a few hours of garage time. You’ll find that thinking time will likely equal or surpass the time it actually takes to fab hardware and hook up components.

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About the author

wayne scraba

Wayne’s byline began with Super Stock & Drag Illustrated and since then, he has toiled as the Editor of many years within 33-years in the automotive journalism field. Wayne has written 6 automotive books.
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