Oil sensor replace on H6 — 2012 Outback

[craigmcd]

I finally tracked down the oil sensor on our 2012 Outback. On this 6 cylinder engine, it is down low, screwed in just above the oil filter assembly.  If I remove the sensor when the engine is full of oil, will it leak all over me and the floor ? Would it be best to do this as part of an oil change, and pull the sensor after draining the oil?

The sensor comes with some red sealant on the threads, is that all I need when putting the new one in?

Thanks for the input! Craig

[FerGloyale]

t will only leak what's in the oil galleries.

That will happen whether you drain the oil pan or not because the pressure sensor is on the pressure side of the pump, not submerged in the sump.

[craigmcd]

I understand, but how much oil are we talking ?

[Numbchux]

It's well above the level in the pan. Barely a dribble, as I recall.

 

Much easier to access with the oil filter off, though. I had a hell of a time getting the new one started with the filter in place. Also I had an aftermarket one on it which used a different sized socket.

[craigmcd]

Sounds great, I’ll do this little job later today. Thanks for the input. C

[craigmcd]

Hi - there is an unexpected wrinkle in what should have been a very simple repair, hopefully one of you can enlighten me on the best way forward. 

I put the Subaru (2012 Outback, 3600cc empi dohc) on the lift Saturday. I had a hard time fitting a large socket onto the sensor because there is another small bolt in the way, which prevents the socket from sliding on. We tried every kind of socket and wrench and plier, but nothing can get onto the sensor, and if I can grip it, I can’t turn it because of the narrow space. 

The solution seems to be removing the offending bolt, which has an Allen wrench head. I hesitated because I don’t know what that bolt does or what it may be securing in the engine block. It is also pretty hard to reach. See my drawing.

Another factor is that the orig sensor is 24mm, and the new aftermarket sensor is 27mm. I already can not get a socket on it,  so increasing the diameter seems to only make the problem worse. Perhaps the new sensor would hit the other bolt before I could get it screwed in all the way.  I will visit some parts stores and try to get a narrower (orig size) sensor.

Part of the solution is to remove the oil cooler, which should be attached by a single center shaft. This would give me room to remove the Allen bolt, and/or put a wrench on the sensor and be able to turn it. I see that it would need a new gasket, but other than that is there any mechanical reason I shouldn’t just get the oil cooler (and filter) out of the way?

On Saturday I had some extra oil and filter, but I wasn’t ready for a complete oil change. I did not pull the oil filter because that did nothing to solve the problem with the Allen head bolt. The sensor is directly above the oil cooler, with about a 2-3” space between them.

Your thoughts please — and thanks. Craig

[FerGloyale]

use a thin wall, 12pt  socket not an impact socket.  It's possible without removing that allen head bolt.

Use a factory sensor.  They aren't that expensive from Subaru so no reason to buy an inferior aftermarket that will cause more problems.

Removing oil cooler is easy.  Get the O-ring from Subaru to seal it.  Worth doing because it's one of the known leak points that will develop on the EZ motor.

[Numbchux]

I did some looking. That allen bolt is likely one of the upper oil pan bolts to the block. Probably could remove it without an issue, but shouldn't need to.

Yea, make sure you're not using an impact socket.

 

Only downside to removing the oil cooler, is in order to really get any more room, you'll probably have to drain the coolant system and disconnect those 2 hoses (easily flexible enough to replace the cooler oring itself...). And this is new enough to call for the Subaru blue coolant.

[craigmcd]

6 hours ago, Numbchux said:

Only downside to removing the oil cooler, is in order to really get any more room, you'll probably have to drain the coolant system and disconnect those 2 hoses (easily flexible enough to replace the cooler oring itself...). And this is new enough to call for the Subaru blue coolant.

Thanks FerGloyale and Numbchux - great ideas which I will pursue.  We had tried a regular deepwell socket, and it was close. I will buy one special for this.

Just to clarify - I thought that oil ran through the oil cooler, is this an incorrect assumption ?  I have NO IDEA where to add the blue coolant for this particular system. So please tell me what you mean by ‘blue coolant’, and how that works with the oil cooler system. Is the oil cooler really just part of the overall radiator cooling system?

Sorry if this seems basic, but as I do more and more DIY stuff, I run into more difficult questions. I did a transmission valve body, so I am willing to learn.

Thanks, Craig

 

[FerGloyale]

47 minutes ago, craigmcd said:

Just to clarify - I thought that oil ran through the oil cooler, is this an incorrect assumption ?  I have NO IDEA where to add the blue coolant for this particular system. So please tell me what you mean by ‘blue coolant’, and how that works with the oil cooler system. Is the oil cooler really just part of the overall radiator cooling system?

 

 Oil does run through it, but only through the center and the rim that oil filter covers.  The lines on the side are coolant in and out.  It's wafer setup. Coolant runs between the wafers, and oil runs through the holes in the wafer stacks.  Should be described more as a heat exchanger, than a cooler really.

The blue coolant is subaru's (and others) special improved premium quality.  Made by Pentafrost IIRC.  But yeah it's just a bit expensive.

I would just move the cooler to the side a bit, not actually remove it.  Slip the new O-ring carefully up into it's groove before reinstalling.  Should be enough to get to the oil sender.

[craigmcd]

Thanks FerGloyale, once I learned of the blue coolant, what you described for the oil cooler is what I imagined.  It is very similar to how coolant flows through an engine, but never comes in contact with the air or oil or fuel.  I am going to buy the O-ring, but hoping to not remove the cooler at this time. Thanks again.

 

[Numbchux]

11 hours ago, craigmcd said:

Thanks FerGloyale and Numbchux - great ideas which I will pursue.  We had tried a regular deepwell socket, and it was close. I will buy one special for this.

Just to clarify - I thought that oil ran through the oil cooler, is this an incorrect assumption ?  I have NO IDEA where to add the blue coolant for this particular system. So please tell me what you mean by ‘blue coolant’, and how that works with the oil cooler system. Is the oil cooler really just part of the overall radiator cooling system?

Sorry if this seems basic, but as I do more and more DIY stuff, I run into more difficult questions. I did a transmission valve body, so I am willing to learn.

Thanks, Craig

 

That's the entire function of the oil cooler, it exchanges heat between the engine oil and coolant. Oil flows through it to the filter and then back through it to the engine block, and coolant flows through it via a pair of rubber hoses. The hoses are flexible, so you can unbolt the cooler from the block and move it around some (plenty for replacing it's Oring). One of those hoses goes to a steel line that crosses in front of the oil pan, this can be unbolted from the engine to gain even more flexibility without opening the cooling system. I'm not sure if it'll be enough to really be beneficial in accessing the oil switch.

In 2008, Subaru switched coolant types. I've seen newer cars with conventional green in them, but I certainly wouldn't mix them, at which point a gallon of Subaru stuff typically makes more sense then flushing the system to replace with conventional green fluid.

Adding fluid isn't any different. I think that setup still has a conventional radiator cap/overflow bottle.

[craigmcd]

On 6/17/2019 at 3:42 PM, FerGloyale said:

use a thin wall, 12pt  socket not an impact socket.

It took 5 stops, but I finally found the socket you recommended. It is not described specifically as thin wall, but it should be thin enough (as thin as many much smaller sockets). Also got the OEM Subi oil sender, and the gasket for the oil cooler should I need to lower it.  Perhaps Thursday I can get back on the lift. Chow