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Mishimoto CVT Cooler

10K views 19 replies 6 participants last post by  Boxerfxt 
#1 ·
One of the main concerns troubling the Lineartronic CVT (or any Autotragic Transmission for that matter) is heat. Heat is the enemy of these poor rubber band drivetrains. So what to do?

A few of you may remember that a while ago, I was having a real big issue with my tranny overheating. It ended up being a combination of the stock cooler being caked in mud, and the CVT Fluid being past its service life.

That process taught me many things. First off, I called a dozen different Subaru dealerships, and NOBODY could tell me either the temp that turns the light on (too hot) OR, the normal operating temp. So I bought a ScanGauge and programmed the CVT Temp. Thought that, I learned that the light illuminates at 265f degrees. I also learned that at 248/249f degrees, the computer begins limiting the engine speed to a max of around 4000rpm in an attempt to keep the tranny from overheating.

After getting it all taken care of and returning back to normal, I learned that the reason nobody could tell me the normal operating temp is because it fluctuates widely. Slower (55-65mph) flat roads can be as low as 190* on a cold day, to getting up into the 240's* on faster (and/or steeper) inclines on a hot day. And it's all perfectly acceptable, kind of...

I have personally noticed that my efficiency and acceleration both suffer with temps about 220. So what to do?

Well, an extensive google search revealed that Mishimoto makes a CVT cooler for 2015+ WRX's for $350. Hmmmm. I phone a friend that works at a Subaru Performance shop, and ask him. He contacts Mishimoto, and they confirm that it fits. Shweet.

Now here's where I ran into a couple issues that you most likely won't.
1). I'm a cheap bastard.
2). I like fabricating things.
3). The Mishimoto mounting brackets place the cooler behind the grille, which is an area occupied by horns mounted on a Paranoid Fabrications mount, as well as emergency flashers. (Supposedly, the Mishimoto mounts have provisions for mounting horns, but that didn't solve my flasher issue.)

So I begin researching what exact components make up the kit from Mishimoto?
- x1 19 Row Oil Cooler (P/N MMOC-19)
- x1 3/8" high pressure hose (6ft I believe, but I ended up using closer to 8ft)
- x2 -10AN Female to 3/8" Barbed Hose fitting (45* angle)
- x1 Mounting Bracket Set

So, referencing point #1 above, I total it up.
- Cooler $157 Amazon
- Hose $~3.50/ft ($28)
- Fittings $5/ea ($10)
- Metal for brackets, I have a ton of spare steel in my garage.

So for about $200, I can have the kit, minus the brackets? Yes please.

One little oversight was that finding the hose fittings was a total PITA. Took me HOURS of scouring the interwebz to find them, but finally found them for like $4.97/ea at Summit Racing.

Okay, next I had to figure out where to mount it. Found a sweet little spot in the lower grille area. And offsetting it allowed it to line up with an existing hole in the lower radiator support. #win

When I finally began mounting, I had originally planned on drilling a couple holes in the crash bar to mount to, but once I took it off to mark the holes, I noticed that it seemed to line up quite nice with the mounting bolt for the hood latch. So that's the route I went. It's mounted on three points:
- Aforementioned hole in the lower radiator support
- Second hole drilled into the lower radiator support
- simple L bracket leading up to mounting bolt for hood latch

Then you just need to run the hoses under the passenger headlight and back towards the stock cooler and trans, replace one of the cooler hoses with your fancy new hoses going to your cooler, tighten down the hose clamps, and fill her up with fluid.

This was the first modification that I've done in a LONG time that had me a little spooked. It was daunting to think about doing this. But it was actually really, really easy. I mounted the cooler yesterday before work, and routed the hoses and filled it up today before work. All in all, probably could be done in 2 hours, and most of that time will be spent trying to remove the hose clamp from the cooler hose on the tranny side. That little bastard was rough.

Picture Time!!












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#2 ·
RESULTS!!
(Numbers are approximate, and remember I am modified, including two size up tires, 2" lift, and big roof rack creating resistance)

Before CVT Cooler:

Ambient Temp - 75f
Idle Temp - 200
Cruising at 60mph - 210
Cruising at 80mph - 226
Smashing up a hill - 239

After CVT Cooler:

Ambient Temp - 85f
Idle Temp - 185
Cruising at 60mph - 200
Cruising at 80mph - 212
Smashing up same hill - 224


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#5 ·
Thank you for doing this. I ordered my scan gaugeII today and my blend mount also.. I'll get on and buy my cooler now. I'm not sure how much fluid is needed to add. Someone said almost a quart ? I'm going to read mine as my car is stock with 2800 miles on it. We can compare your bigger tires and high drag coefficient and see the difference.

Thanks again mike
 
#7 ·
I ended up adding about 2/3qt. About 1/2qt goes into the cooler. The install instructions from Mishimoto said to fill cooler, then lift vehicle on flat ground and fill until it dribbles out the fill hole, just like you'd fill it normally. I felt this did not account for the hose capacity, which are higher than the fill plug. So I added a little extra fluid through the hoses to account for the added volume.



Just get some flat bar from the depot for the brackets? What did you end up using?

Yup. 1"X36"x1/8" bar



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#9 ·
Nope. The gold is beautiful. I would have gone with it, but mine is exposed and I didn't need any unwanted attention. It's too secure to steal, but I cringe to think of the damage caused to it and/or my condenser from someone trying.


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#12 ·
So over the past couple days, I had to drive from SoCal, to Vegas, down to Phoenix, and then back home to SoCal. While staying in Vegas, I decided to drive down to the Christmas Tree Pass between Searchlight and Laughlin. It ended up just being basically a dirt road. A few ruts, but nothing to test the cooler. But I did get some cool pics.







She did awesome on this round trip. Highest temp I saw was 228. And that was yesterday between Tonopah, AZ and Palm Desert, CA, ambient temp between 87-92 the whole way. Speed limit is 75 most of the way, and I was driving straight into 45mph winds with gusts over 65mph. Maintaining 75mph was a struggle with my high resistance factor. Engine was turning at 4000-5500 most of the way, and never dropped below 3500 except a couple times when slowing down to let a big rig over. Gas mileage was horrendous, but the tranny stayed cool.


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#18 ·
My car is 100 percent stock. It was bought may 4th 2016 and just turned 3100 miles
It did pretty well I was surprised most of the time I never know the car trailer was there. Except when the blind spot monitors would go off in gradual turns. I think the trailer being wired than the car it thought someone was right along side of us? But it did fine on the hills i even managed to pass some people in the passing areas of us50?
 
#19 ·
The highest I would let the engine spin was 4200 I left it in drive for the climbs and would use the paddle to hold a gear or two down hill. It's nice it holds a downshift even when you hit the brake the only time it will go back to drive is if you touch the accelerator
 
#20 · (Edited)
So rallyebourne have you been watching your temps? And at what temperature does it limit engine rpm? Also what temp would the max you let the transmission get? 250? 260? Before the fluid does damage to the cvt? My experience is even when you hold the gear in manual mode the temp seems to climb more than if you let the cvt pick the ratio?
 
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