Hi guys,

I was changing the rear rocker cover gasket today and noticed that the plenum, throttle body and intake manifold are covered in carbon deposits.

Does this seem like too much? Car has 181K km
Would there be a benefit to clean them? And if so, how would I do it (ie, just some of that seafoam stuff?)

Here are pics:

http://i26.photobucket.com/albums/c104/spetz83/IMG_0657_zps4656f6ac.jpg

http://i26.photobucket.com/albums/c104/spetz83/IMG_0651_zpsa916d0c4.jpg

http://i26.photobucket.com/albums/c104/spetz83/IMG_0648_zpscdc5a0c1.jpg

http://i26.photobucket.com/albums/c104/spetz83/IMG_0656_zpsb00ede6c.jpg

http://i26.photobucket.com/albums/c104/spetz83/IMG_0659_zps71da3231.jpg

If you are an OCD type of person, give it all a good scrub. Then again, it would be all over the inlet valve stems and piston crowns too. So where do you stop?
Personally, I'd just clean out the throttle body. Supposedly gives a smoother idle. How to clean? No idea myself, something like brake cleaner or seafoam may work.

The most likely source of this carbon build up is the crankcase ventilation, the hose that joins the air ducting just before the throttle body. May be worth while cleaning this hose out, or making up a longer version from fuel line, and installing a filter of some sort in it. A clear one would let you see what grot it collects, and how fast.

Looks pretty normal to me.
Just check the throttle body for any buildup. Don't think you have too much to worry about.

Usually caused by PCV blow-by. Oil vapour is vented off the heads by means of the PCV valves. This is dumped back into the system for emissions purposes.

Side effect is a build up of gunk. I reccommend cleaning it up as this can have numerous minor side effects such as a sticky TB. You may also see a small improvement in performance and economy after cleaning.

Use a carb cleaner to rid the nasty stuff and use a specific AFM cleaner to clean the AFM itself as this is likely to be dirty too.

Check that the PCV valves themselves are working. You should be able to blow through one end but not the other

Looks pretty normal to me.
Just check the throttle body for any buildup. Don't think you have too much to worry about.

Yes, meant to say it looks ok for the Km the engine has done.
(Engine workshops have a huge vat of hot circulating caustic liquid that is used to clean up this sort of thing, so it is quite common. Goes all nice and shiny and new looking.)

Thanks guys.

Where is the second PCV valve? I only saw the one on the front bank.

The AFM looked clean.

Would the engine stay clean if I installed an oil catch can?

to clean it use a can of carby/tb cleaner as mentioned.i uses for mine SUBARU Upper Engine Cleaner which is powerful stuff

As said above, the throttle body would definitely need a clean. This amount of gunge would likely be causing a rough idle too. Check out Madmagna's TB cleaning tutorial here (http://www.madmagna.com/) under Tech Tips, this goes through the TB cleaning process in nice detail. I did this myself a couple of weeks back and the TJ is idling better than it ever has since I've had it... just wish I'd found this years ago! There's only one PCV valve at the left side of the front bank, circulation runs from the air cleaner to the rear bank, from the rear bank to the front bank via a hose to the right of the engine, and from the front bank to the manifold via the PCV valve. It's worth checking that these three hoses are all clear, mine were chock full of evil so I replaced them all. If the transfer pipe is blocked then your fumes will be running back up the intake pipe and through your TB, there will always be a little bit of this particularly if your rings are a bit worn so cleaning the TB should be a semi-regular thing (annually maybe?). Definitely worth it for an hour or two's work, you'll notice a big difference. I'd also tidy up the plenum but maybe I'm a bit OCD!

A smoother surface technically allows for better air flow. I took my intake off my old car, separated the two parts and cleaned it good and proper. I can tell you I noticed absolutely no difference, but there is bound to be "something" in it.
Good luck!

It's not so much the crap you can see, it's the crap in your idle air bypass channels. If your bore looks like this it's a safe bet your ISM, vac outlets and idle speed set screw channels are at least partially blocked.

They get cleaned in a TB clean don't they?
I have been planning on doing them when I service the car next.

Probably just get some Subaru upper engine cleaner for the res