CVT and Off-Road - Subaru Outback - Subaru Outback Forums
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post #1 of 19 (permalink) Old 12-21-2016, 12:29 PM Thread Starter
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CVT and Off-Road

Hello, this will be my first post on the forum. I have tried researching an answer to this question through google and searches on here, but I couldn't find a straight up answer to my question. I apologize if this has been covered in other threads.

Short version of question:
Does off-roading impact the life expectancy of the transmission valve body?

Long version of question:
I have a stock 2011 Outback (2.5i Premium) and recently had to get the transmissions valve body replaced (still at the dealer waiting on the part to arrive). The subi has just north of 90k miles on it, this week we were going to bring it in for the 90k maintenance. My question is, could off-roading have been the cause for the valve body failure? My wife and I make pretty frequent trips to Big Bend National Park and pretty much keep it in the dirt the whole time. We found that with some technical driving you can bring it pretty much anywhere in the park (yes even Black Gap Road/Old Ore Road/Christmas Mountain). On the way home from our last trip the the lights came on for the AT Oil Temp along with all of the usual lights that come on with the check engine light. This was after a few hundred miles on the highway and not on the trail. This trip wasn't any different than our trips in the past, so it wasn't any more/less rugged than others. From what I've read there are really only two reasons for the valve body to break, defective part or low trans fluid levels. Looking at other valve body failures online the defective body generally fails before 60k miles and I asked about the level when they started looking at it yesterday and they said it was fine. I don't fully understand it's role in the transmission so I'm wondering if the strain from off-roading or excessive dust could have caused the issue. The dealer said every time he has seen one fail it was due to not maintaining it, I assume not changing the fluid at 30k mile intervals. Since we got the car we just put 30k miles on it coming back from our last trip. So the maintenance issue would have been from the previous owner. It's a pretty expensive fix so I want to avoid it happening again, so if laying off the trails will prevent it I'm hoping to find that out. However I would hate for that to happen since it does so well. This is coming from someone who had a Jeep with 5+ inches lift, 35" tires, lockers, etc. My only complaint with it off-road is the limited approach/depart angles with the stock bumpers.

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post #2 of 19 (permalink) Old 12-21-2016, 06:43 PM
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Do you run a transmission cooler? To me doing that kind of driving without one would be suicidal for a trans.

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post #3 of 19 (permalink) Old 12-22-2016, 09:16 AM Thread Starter
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No trans cooler, so that could be it. Generally when there is any kind of obstacle or it's slow going I keep it in "manual" to stop the transmission from shifting when I don't want it to and to hopefully keep it from working harder than it needs. However the second part of that might be the equivalent of sacrificing chickens to make it rain.
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post #4 of 19 (permalink) Old 12-22-2016, 11:03 AM
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Off road in BBNP is pretty mild insofar as off roading goes. There is not much elevation, no bouldering, hardly any water crossings to speak of (it's in the Chihuahan desert!) . There are some challenging spots but overall it is nothing like Colorado or Utah. I'd almost think driving on I-10 in west Texas at 80+mph might be harder on the CVT than slow crawling in BBNP. High speed driving makes lots of heat.

That said, your modis operandi of putting the selector in manual certainly helps by alleviating the CVT from searching for the best ratio as conditions change.
As for the valve body failure, I would venture that it did not "break" since the valve body itself is but a hunk of metal that hold spool valves, springs, check valves, check balls and solenoids. It does not have much if any structural loads upon it. 30 years ago, The VB was made of cast iron or steel but I would imagine these days they are aluminum alloy to save weight.
Failure of the valve body could be a spring failure, solenoid failure, leaking spool valve, stuck check ball or valve. Even a gasket leak could cause major problems. Given the way Subaru treats the CVT, I could see the service center simply replacing the entire VB rather than making a surgical repair.

What could have happened in your situation is the internal filter/screen got clogged by sediment that normally sits in the bottom of the pan but was agitated by the off road bouncing and jostling. That's a theory.
I don't think dust could have worked its way inside the CVT. Although there is a vent tube, dust would clog the tube before enough of it migrated into the transmission to cause problems. The vent tube is bent and curved to make a torturous path for anything trying to work its way in.

Sorry you had to deal with this failure. I do plan to get my OB out to BBNP sometime, so I am glad to see you have been able to negotiate any of the trails out there.

As an ironic anecdote, my closest dealer did not seem interested in doing a CVT fluid change when I asked about it. I will most likely end up doing it myself.
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post #5 of 19 (permalink) Old 12-22-2016, 11:31 AM
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My 2013 OB is my first experience with CVT. No off-road, just city/highway, but I use the trans severe service maintenance schedule because it does a lot of shifting in that use. I understand differing opinions on whether my practice is insurance or paranoia, but the dealer had no objection to adding CVT fluid to the 30K service.
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post #6 of 19 (permalink) Old 12-22-2016, 12:15 PM
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Earlier this year I asked around about installing a cooler on mine. The consensus seemed to be "couldn't hurt" but there were a lot of people saying it's unnecessary. Maybe for them but I do things like this more often than I should:


Think a cooler got bumped up the list as far as things to do to the car. Never going to get around to that dash can.
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post #7 of 19 (permalink) Old 12-22-2016, 11:43 PM
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My car has a very different powertrain, but what does impact ATF temps, whether off-pavement or when towing a small trailer on the interstate, is hill climbing, specifically the combination of length, grade, speed, and load. The more one or more of these four components increases, the more at least one of the others needs to decrease.
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post #8 of 19 (permalink) Old 12-24-2016, 05:34 AM
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georgeXcore,



I can't contribute much, but I get excited whenever I see the words Big Bend. One of my favorite places on earth.

I've had my 2013 2.5 CVT (with 16" BFG AT KOs) out to Big Bend, and Black Gap WMA, 4 times so far. Been over many of the more civilized back country roads, but I chickened out on the Old Ore Road after a mile, at the entrance on the main Park road, coming west from Rio Grande Village. I also chickened out on the Paint Gap road north of campsite #3 after about 1/4 mile so looks like I'm a lightweight off-roader by comparison to some of you all. My hat is off to you guys.

More that I felt I was beating the car up than worried about making it. I guess that's what makes me a lightweight.


All my Big Bend time has been Nov-Feb, during the cooler months.

I've also spent quite a bit of time on Padre Island National Seashore, down to around mile 22. Probably made that trip 25+ times in my 2013.

The second I leave the pavement until the time I get back on it I'm CVT "manual"-VDC "off".

I like keeping my rpms higher on the power curve than the CVT would like to have us at, for a quicker burst of oompah when necessary, and the better engine braking on descents.

With just 62k miles on my Outback I guess time will tell. But the joy the CVT ability gives back country makes it worth the "risk" for me. Why have the Outback otherwise?

Sorry for your situation, and hope it comes out well.

This is from Feb 2014, before the BFG AT KOs. (Excuse the darned rotation, its upright when attached)
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post #9 of 19 (permalink) Old 12-24-2016, 07:29 AM
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Has the CVT fluid been changed since 90k. I think 30k changes are good
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post #10 of 19 (permalink) Old 12-24-2016, 02:49 PM Thread Starter
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Thanks for the replies and it makes me feel a bit better about what I've been doing with it. As someone mentioned the roads at BBNP aren't bad, but for some reason people think you need 4 wheel drive (AWD apparently doesn't count) and a lift to get through some of the roads. I've gotten the "a car like that has no business back there, you need a 4 wheel drive SUV/Truck with at least a few inches of lift and way bigger tires" a couple times. If anyone goes out there, don't believe that fear mongering. The roads don't any big hill climbs but the kicker is the silt piles, wash outs and step ups. The obstacle might only be knee to chest high, but how steep the incline is makes for some technical driving to make sure you leave with both bumpers. The AWD on the subie is way better than the 4 wheel drive on my old wrangler (well.. before the lockers ). There are lots of times where 1 or 2 wheels are in the air and the thing still pulls up and over like it's nothing. After the first trip taking the 4x4 only roads I picked up as much armor for under the car as possible, I did touch the center a few times on the roads. Then after 2 flat tires from other trips out there I went from passengers to Geolander A/T's, but really if you want to live on the edge you really don't need anything extra. That park is still on top of our list for favorites and I don't know if it's because of being able to drive there or the fact that there are so few people there every time we go. Almost every trip we split between camping and staying at the lodge. Our favorite camp site so far is Twisted Shoe, but it's back in there. It takes just about two hours on a dirt road (categorized as primitive) to get to/from it, but it's worth it. Second favorite campsite is a random location near Mariscal Canyon (on River Road park at some turn I can't remember and just walk two hours into the dessert). Like I said thanks for the suggestions, even if it's overkill I might throw on a trans cooler. They are a pretty inexpensive add-on to keep the transmission a bit more comfortable.

Also we just turned over the 90k mile mark on the way home from that trip. We got the car with right on 60k miles. So this would be the first transmission maintenance interval we hit while owning the car and I don't know if the previous owners did it like they were supposed to. The dealer said it looks like it has never been changed, like in ever. However I don't how they were coming up with that.

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