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2017 Forester 2.5i 6-speed manual
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Discussion Starter · #1 ·
Hello all,

Two questions related to the PCV valve:

1) Should I check/replace it? It is part of the C-check for my Canadian '17 Forester 2.5i, however the service manual says "do not remove unless the PCV valve is broken". I am not aware of a way to know if it is broken without removing it, hence the dilemma.

2) The service manual makes it look easy: just pull off the hose, unscrew the valve, check it, and put it back. However access looks complicated; I cannot fit my hand in there to remove the hose, so I cannot remove the valve! Any tips/videos that could help?

I saw some old posts but not sure they would be applicable to my 2017.

Thanks!
 

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Let me start off by saying I am not a mechanic so use your own good judgment.

The reason it's says not to remove is most likely because they are trying to stop people from venting to atmosphere.
Many people try to vent the emissions to atmosphere so that it reduces carbon buildup on the valves etc.

I personally see no reason not to remove it and inspect it. Be extra sure the area around it is clean so that nothing drops into the opening. I would wipe away any dust/debris. Remove it to inspect. Most people use some Teflon tape on threads when reinstalling. If you do, make sure no Teflon tape is covering the end of the valve, threads only.

If you break the valve loose with a socket and a long extention , you can either pull it out by and or use a pair of grippers/clean telescoping magnet.

I found a short video that shows how to do this on the fb25 engine as well.
 

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2017 Forester 2.5i 6-speed manual
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Discussion Starter · #3 ·
Thanks for your great response! I am concerned about being able to access the valve after re-installing to attach the hose, but I'll give it a shot or find someone with small hands to help.
 

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2016 Forester 2.5 Limited
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51 Posts
I'm considering doing this to my '16 Forester as it states to inspect or replace if necessary (60K service). I don't want to throw away money but being that a new valve is $35 it doesn't seem like much more effort to just replace instead of inspect.
 

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2015 Forester 2.5i Limited CVT
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The PCv valve is a simple check plug. Easy to clean and reinstall. I use a little Teflon tape. I think Subaru specs a liquid gasket seal. One of the FujiBond thread sealants. Some brake cleaner spray should be enough to clean it. I wouldn’t bother unless there’s a problem. I think this can wait.
 

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2012 Forester 4 speed auto
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1,128 Posts
Don't worry.

You would know that a possible PCV failure has happened because the engine would stall, surge, and just run poorly. If any thing goes wrong it is the hose becoming unattached and dumping oil- blow by, in the engine compartment. As long as you change your oil, air filter, oil filter your PCV will be fine.
 

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2017 Forester 2.5i 6-speed manual
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Discussion Starter · #7 ·
Just changed the valve. I was surprised by/observed a few things:

1) the old valve had oil residue on both sides, and the loose piece ("pea" if I use the whistle term) was loose yet clearly surrounded by liquid. Is this normal? I have about 50,000 km / 31,000 miles.

2) only the PCV valve end of the hose needs to be removed for access.

3) 17 ft-lbs is not a lot of torque. The new valve I installed had a lot more threads than the old one, so it is not possible to eyeball whether it is all the way in. I don't have much confidence in the torque applied because I had to use multiple extensions to reach the valve, and also reach it from an angle. Is this a problem?

4) Further to the oil question, I wonder how well the teflon tape I applied will hold up to the hot engine oil it is obviously exposed to?

Overall, if all this is ok/normal, it was a very quick job I would not hesitate to do again next time.
 

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The torque isn't that critical. The teflon tape will hold up.. But next time I would recommend using a liquid sealer because the teflon tape or pieces of it can fall into the motor when you next remove it.
 

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2017 Forester 2.5i 6-speed manual
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Discussion Starter · #9 ·
Hi PearlWhite, good point about the pieces of tape. Is there a particular liquid sealer you could recommend?

The service manual requires Three Bond 1324, but I can't find that for sale anywhere. I found this link which states that Permatex 81160 (Red RTV High-Temp Gasket Maker) can be used instead (among others). I went to buy this stuff, and the salesperson told me that using the RTV would make the PCV very difficult to remove. He suggested using blue thread locker, but while that might prevent the valve from loosening, I did not think it would help create a seal.
 

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The threads are self sealing tapered, AKA NPT national pipe taper. 9 times out of 10 you don't need to apply anything. When an NPT fitting leaks it's normally due to metal on metal galling causing a rough surface at the metal to metal thread interface. For plumbing one would normally use a pipe dope applied to the threads. Pipe dope is basically a grease with suspended copper or teflon particles to lubricate the joint during assembly. Some pipe dopes are pretty gritty so ya might not want them mixing with say your clean motor oil. I would use a small amount of non hardening pipe dope or thread sealant made for this application, like Permetex thread sealent, or a heavy oil or greese for assembly.


Again, the threads are self sealing, just use a lubricant during assembly.
 

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2017 Forester 2.5i CVT
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Let me start off by saying I am not a mechanic so use your own good judgment.

The reason it's says not to remove is most likely because they are trying to stop people from venting to atmosphere.
Many people try to vent the emissions to atmosphere so that it reduces carbon buildup on the valves etc.

I personally see no reason not to remove it and inspect it. Be extra sure the area around it is clean so that nothing drops into the opening. I would wipe away any dust/debris. Remove it to inspect. Most people use some Teflon tape on threads when reinstalling. If you do, make sure no Teflon tape is covering the end of the valve, threads only.

If you break the valve loose with a socket and a long extention , you can either pull it out by and or use a pair of grippers/clean telescoping magnet.

I found a short video that shows how to do this on the fb25 engine as well.
Why does Subaru put it way down there rather than on top of the upper intake manifold? Seems stupid. It requires people to have small hands to get all the way down there. would have been easier to just stick it on the top.
 

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2015 Forester 2.5i Limited CVT
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1,491 Posts
I found that the thread sealant for the 2015 Forester requires Threebond 1217H. A silicone sealant. Grey in color. I don’t know when it was changed from Threebond 1324, which is a high temp, oil resistant thread locker.

My replaced pcv valve had remnants of the grey silicone. I plan on buying the 1217H. I don’t think Teflon tape will hold up well. It’s not made to be oil resistant.
 
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