The green connector is, I believe, the variable valve lift solenoid, and the white connector is the VVL oil pressure sensor for the left side. Certainly looks as if the sensor is leaking. Is there a pool of oil below the sensor, or stains that suggest it's burning off?

There's an identical set of the solenoid and sensor on the right side, but instead of being at the front it's at the back. That will provide a comparison.

Even if this isn't the cause of the loss, it could be contributing to it. But I think you've probably found it.

 

Yes there's a pool of oil all around that area and it drips onto the exhaust choking me out of the car. I'm taking it to Subaru in the morning.

 

Please let us know if that is what it turns out to be.

 

Found out today it's the VVL oil pressure sensor on both heads. Part is not under the powertrain warranty. Although under the powertrain it does say oil seals. Would this be considered an oil seal? Part is only $16 and the tech said it would take about 1.5 hours to install both. That seems high.

 

The oil pressure sensor is, unfortunately, not an oil seal. It's the same type of device as the engine oil pressure sensor, the one that would cause the oil pressure warning light on the dash to come on if the oil pressure is low. Essentially it's an on-off switch that changes with the level of oil pressure in the line it is monitoring. Leaks in these switches are not uncommon.

The ECM changes the lift (opening) of one of the two intake valves in each cylinder depending on the engine speed and load. At higher speeds, the lift is higher, allowing for a more open flow of air/fuel mix into the cylinder. At lower speeds, the lift is lower, causing a particular swirl action of the incoming mix which is supposed to provide smoother and more efficient operation.

The change from low to high is mechanical. There are two cams, a high and a low lift, on the variable valve. The switch from one to the other height is effected by oil pressure. The oil pressure is varied by the VVL solenoid which is controlled by the ECM. The VVL oil pressure sensor monitors the pressure going to the cam-changing mechanism. When the ECM signals the solenoid to change, the pressure should change. If it does, then the ECM assumes all is well. If the pressure in the line doesn't properly correspond to the signal sent to the solenoid, the ECM will trigger a trouble code and the MIL (CEL) warning light comes on. (Note, the pressure sensor can only detect whether or not the pressure in the line is correct. It does not determine if, in fact, mechanically there has been a changeover in the cam and a corresponding change in the valve lift height.)

It's disappointing that the sensor is, supposedly, not part of the power train warranty. In fact, that's strange. It's an essential part of the engine fuel system and of the On Board Diagnostic system, which relates directly to the "all important" issue of emissions. I wonder if it might be worthwhile to verify with Subaru on this.

Part price seems reasonable. According to the service manual, changing the sensor appears relatively simple -- disconnect battery, disconnect sensor, screw out, apply sealer to the new one, install, reconnect. The one on the left front is out in the open and should take very little time. However, the one on the right rear is in a rather awkward spot there might be some other stuff to move out of the way which would add to the time.

This isn't the first time there's been a report of the sensor or the solenoid developiing a leak. But I'm surprised that both of yours are this way.

Let us know the outcome.

p.s. How many km/miles on the car?

 

That's for your reply. I will contact SOC and see what happens. The car has almost 95000kms. I'll be going in for the 96km service 2 weeks from now. I might get the sensors and try it myself.

The tech warned me that if I did do it there was a risk of splitting the head. Is this true?

 

So you're still within the 100k km warranty and the 5 years.

I don't know about the "splitting the head" issue. Perhaps he mean casting, in the vicinity of the sensor, could crack if the sensor is overtightened. (I believe the switch has a form of pipe thread connection.) There's a torque spec for installing the switch -- 12.5 ft-lbs, which isn't much, so overtightening could be a potential problem, but not if appropriate care is taken. A thread sealer (Three Bond 1312 or equivalent) is supposed to be applied to the threads, and that reduces the need to tighten it down too much, while ensuring a good seal.

But do see what SOC has to say. Maybe, even if the switches aren't formally covered, it will do so as a "goodwill" measure, especially if the car has been regularly serviced and is going in for the 96k.

 

I had a look also at the rear one and it doesn't look like it's leaking and also not that hard to get to.

 

That's good. Wonder why the tech said both were leaking. Perhaps only one side needs work, or perhaps they're thinking of a preventative measure.

Here's an earlier thread on the same problem, along with a link to a related one. http://www.subaruoutback.org/forums/74-outback-4-cylinder/23215-oil-blowout.html

Suggestion. Wipe down the switch and the area around it as best you can, and then watch more closely to see where the oil is actually coming out from.

 

A bit late is posting here but I still don't have this done and it's still leaking. I have another question before putting the new ones in.

If it's leaking but still working why do I put another one in? If it's only leaking can't I just remove it...clean the area up and put it back with some sealant to stop it from working?

 

The leak is probably not at the threads where the switch assembly screws into the block. Instead, it's more likely a leak around/through the internal diaphragm seal between the lower, metal base, and the upper plastic part that encloses the electrical switch itself. This cannot be repaired or sealed and, if anything, can get worse.

Any mechanic should be able to change it -- many car engines use similar oil pressure sensor switches (there's one used for the oil pressure warning light on the instrument panel that most cars have) and they are a common replacement part so it's something a mechanic should be familiar with. If only the one switch is leaking, then you don't have to change both.

 

OK...finally good enough weather to change this out today. Went to the dealer to get the thread compound and the tech didn't know what I was talking about. He said they just use Teflon tape and to hand tighten and to be very careful. Man I've never been told so many times to be careful with this install. What's the head made out of cheese.

I'll update in a bit. I'll take pics along the way plus the occasional beer.:gmb:

 

Cleaned area.

Old part...pretty grungy.

New vs old.

Installed! About 15 min including cleaning the area. You need a 15/17" deep socket.

...and the beer.

Checked a few times and no leak.:29:

 

Thanks for the follow-up.

Looks simple enough.

Did you use a torque wrench to install, or how did you otherwise decide when to stop tightening given the warnings?

 

I tell you for something that's supposed to be put on with 12lbs of torque is was a bitch to loosen.

I just tightened it until it looked like it was in the right position height wise and feel. The nipple it screws into is pretty heavy aluminum so I can't see how it can split but I wasn't going to be testing my theory. lol

 

The thread sealant was what made it hard to remove. The cautions about splitting the head were more likely about splitting the head of the sensor which would just cause the same leak again.

 

Awesome thread right here. Good to see everything worked out

 

I had exactly the same problem on my 2007 subaru outback! Thank you for this article. Dare i say - if it wasn't for this article i may have not made it out of this pickle without paying $$$! Here is my story:

Check Engine Light comes on. I don't really notice anything wrong, but i get the code read "P0028" something to do with the 2nd valve bank yada yada..... Absolutely no help whatsoever. I clear the code and drive away from NAPA. within five miles i have smoke coming into my car via the HVAC. I pull off the road and smoke pours out of the engine bay. Luckily i happen to be within .5 miles of the subi dealer. As i pull in with a smoking subi, i ask them to take a look at it. They do and tell me all i need is a new oil pressure switch. Very common apparently. I ask if i can grab one, and they give me this line: "Sorry the register just closed 2 minutes ago" After some fairly descriptive expletives, i go on my way, with my money and business and smokin car to go home. The next day i make it to the next nearest dealer and get the part, install it with a deep 15/16th socket and silicon tape, and voila! Fixed.

 

This is my first Subie but it is good to see that it can be worked on so easily.

 

You guys just saved me from Pulling my engine to check rear seal or separator plate. Stupid leaking Oil Pressure Sensor on the VVL. Replaced and no more leaks!!!!

 

How do you get the VVL oil switching solenoid on and off? I know this thread has talked about the VVL pressure switch but can anyone tell me how to get on and off the solenoid?

 

I just replaced this switch on my fiance's 2006 Impreza 2.5i. I used loctite 271 and was very careful to not overtighten. I checked it the day after and it was not leaking at all. I will check again in a couple days