Throttle body PCV -- lower vacuum hose or bypass valve
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Thread: Throttle body PCV -- lower vacuum hose or bypass valve

  1. #1
    Hi, quick question regarding routing the PCV with check valve onto the throttle body.

    The red pipe is the lower vacuum hose, and the blue pipe is the bypass valve:



    Is it the bypass valve (blue) that is part of the PCV system and routes to the cam-cover?

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  3. #2
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    The blue hose goes to the cam cover and has the check valve and is part of the PCV system as you say. The check valve must allow air from the cam cover towards the throttle body, but not the other way.

    The red hose goes towards the firewall at the back of the engine and via a few other connections it goes to the (turbo) bypass valve at the front of the engine.

    The white (in the drawing), thicker hoses, (also labelled 8!?!) are the throttle body coolant hoses.

  4. #3
    Think I may have confused the red and blue hoses in the above picture. Is the red hose the bypass valve, and the blue hose the lower vacuum hose (it does seem to be lower in the picture)? When replacing the PCV system, the previous check-valve from cam-cover was on the TB at the red hose--so when replacing, went ahead and put the check-valve where the red hose is. Is this correct? Thanks

  5. #4
    Just found a photo on platonoff.com concerning this issue, backing up how you've described this, SuperSwede. In this photo the check-valve is below the coolant lines, and to the left of the coolant lines is the yellow line for the turbo bypass-valve:



    So before I replaced my PCV system, it was already put together incorrectly (i.e., turbo bypass-valve and cam-cover check-valve being criss-crossed)--and in continuation of this, I've had them criss-crossed since replacing the PCV. Guess I'll be heading outside to put it together correctly

  6. #5
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    Here are two pictures from when I changed my PCV system (see here).

    The hose with the 'ECO' writing on it is the red hose from your drawing and goes towards the firewall at the back of the engine. You can just see the lower hose where it connects to the throttle body and then it bends around to the left. The white canister connected in-line is the check valve. It then carries on and connects to the cam cover together with a thick hose (which goes to the oil separator on the back of the engine).


    Here you can see that same hose (marked in red) connected and disappearing towards the back of the engine. Ignore the blue and yellow markings.

  7. #6
    Just took off the bypass-valve that was hooked on below the coolant hoses. It was very oily on the outside, and when setting it down it started dripping oil, lol. Ran it once with the hoses on correctly and it seemed OK.



  8. #7
    Should I be considering taking out the TB for a full once-over? Also, with all the oil in the bypass valve, how about replacing the vacuum line to--where does it go to? A pressure regulator?

  9. #8
    Full throttle
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    Apart from dirt in the throttle body, the main cause of problems is said to be the solder connections on the circuit board.

  10. #9
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    Should I be considering taking out the TB for a full once-over?[/b]
    Probably not a bad idea. I removed my TB and gave it a good going over a while back. Engine felt a better after that. See here for a few pictures.

    A good check/replace of the vacuum hoses wouldn't go amiss either as well as making sure the check valve does what it's supposed to do.

  11. #10
    Took off the TB following your great post, SuperSwede. Did this last night and cleaned it--reinstalled it this morning. There was quite a bit of gunk inside, including a blackish ring below the butterfly (2" or so). Also adjusted the throttle cable, as there was quite a bit of slack in it.

    After putting it back together, started the engine and it idled quite high--2K rpm for awhile--it's usually near 800. Took it for a drive and about 2-3 minutes in the idle had settled back to the normal range. Also put the top of a pen into the top hose of the boost control valve, ha ha.

    Now looking into a sizable oil leak from the belt-side of the engine, and also kind of the back. It's getting onto the belt and spraying everywhere , ha ha!

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