Engine bay plumbing/inlet manifold HELP!
#1
Engine bay plumbing/inlet manifold HELP!
I'm about to rig up an oil catch tank system and I've followed the blurb on one of the other threads ('Catch tanks and PCV systems' which ran to 6 pages) but I'm getting to the stage now where I just need to SEE what's actually going on rather than talking about it. The theory I'm fine with, now I cannot take in any more until I can actually picture what I'm supposed to be doing.
Now it strikes me that there's one thing that's really hindering my understanding of where all the breather hoses, vacuum pipes and the connections off the induction pipe go...the inlet manifold! It's right in the way and I can't be sure of what's going on under there. I want to see how this PCV valve plumbs in under the throttle body, and I can't get at it. Where the o/s rocker cover breather goes I just cannot work out, although the n/s one seems obvious. I think I can see the crankcase breather but I'm not sure if I'm looking at the right thing.
I know the obvious thing is to take the inlet manifold off to have a look, and if it was the height of summer without a cloud in the sky and an empty weekend stretching ahead of me, I'd do just that. But firstly I've never taken an Impreza manifold off and don't know whether there'd be loads of gaskets I'd have to change etc, and secondly it seems a hell of a lot of trouble just to look at the routing of a handful of oil breather pipes.
Anyone got a clear picture of an engine bay minus inlet manifold but with oil breathers still in place so I can see where they go to and from? Or even better a pictorial 'walk-through' showing step by step how to remove the manifold? I've got a 98 WRX wagon btw if that makes a difference.
All help or advice appreciated!
Now it strikes me that there's one thing that's really hindering my understanding of where all the breather hoses, vacuum pipes and the connections off the induction pipe go...the inlet manifold! It's right in the way and I can't be sure of what's going on under there. I want to see how this PCV valve plumbs in under the throttle body, and I can't get at it. Where the o/s rocker cover breather goes I just cannot work out, although the n/s one seems obvious. I think I can see the crankcase breather but I'm not sure if I'm looking at the right thing.
I know the obvious thing is to take the inlet manifold off to have a look, and if it was the height of summer without a cloud in the sky and an empty weekend stretching ahead of me, I'd do just that. But firstly I've never taken an Impreza manifold off and don't know whether there'd be loads of gaskets I'd have to change etc, and secondly it seems a hell of a lot of trouble just to look at the routing of a handful of oil breather pipes.
Anyone got a clear picture of an engine bay minus inlet manifold but with oil breathers still in place so I can see where they go to and from? Or even better a pictorial 'walk-through' showing step by step how to remove the manifold? I've got a 98 WRX wagon btw if that makes a difference.
All help or advice appreciated!
#3
Nick, my engine bay is stripped enough to show the hoses etc.
Seeing as it is you, i will pic everything i think you need to get you there, home and dry.
Will post here about tea time today, sat.
Graham.
Seeing as it is you, i will pic everything i think you need to get you there, home and dry.
Will post here about tea time today, sat.
Graham.
#6
PCV you can see under the throttle body above the big metal pipe...
IIRC a hose fits between the PCV and one of the crankcase breather connections..
IIRC the smaller diameter metal pipe links the breathers from the cylinder heads to a T section where it then runs a hose onto the inlet pipe.
IIRC a hose fits between the PCV and one of the crankcase breather connections..
IIRC the smaller diameter metal pipe links the breathers from the cylinder heads to a T section where it then runs a hose onto the inlet pipe.
Last edited by AlanG; 26 November 2005 at 04:46 PM.
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#9
Brilliant! Many many thanks to both of you. I'm gonna have a good look at it again tomorrow morning then.
Maybe I'm missing something but cannot the existing metal part of the breather (the bit that goes all the way across with a T-piece in it) still be used?
There are a few bits that don't quite make sense yet to me, but no doubt when I look at my own engine bay it'll be easier to compare.
What I seem to have at the moment is this:
n/s rocker vent is connected via a shortish rubber hose to a metal pipe under the manifold. This turns back into a rubber hose again on the opposite side and connects straight into the side of the inlet pipe.
o/s rocker vent goes over the top of the inlet pipe in rubber hose, then just seems to disappear off somewhere under the throttle body/ manifold. Doesn't appear to plumb back into the inlet pipe at all.
Can see the crankcase vent that you've pointed out but not sure if I remember it having two take-offs? Will check. Presumably you leave one going straight to the PCV valve so I don't have to muck about with that at all?
Last thing, and sorry if this was mentioned on the other thread - I got confused LOL:
If the rocker cover vents serve two purposes - i.e. as a source of clean air to replace contaminated air being drawn out of the crankcase vent, AND actually serving to vent out to the inlet pipe themselves at times, how does this work once you lose the inlet pipe connections?
And the very last thing - I do want to be green, seriously. I recently put in a 'sports cat' downpipe rather than a decat. How does the system work if I want to feed the vapour-free gas back into the engine? Could I use a tank simply as a remote interception system rather than an open catch tank?
Maybe I'm missing something but cannot the existing metal part of the breather (the bit that goes all the way across with a T-piece in it) still be used?
There are a few bits that don't quite make sense yet to me, but no doubt when I look at my own engine bay it'll be easier to compare.
What I seem to have at the moment is this:
n/s rocker vent is connected via a shortish rubber hose to a metal pipe under the manifold. This turns back into a rubber hose again on the opposite side and connects straight into the side of the inlet pipe.
o/s rocker vent goes over the top of the inlet pipe in rubber hose, then just seems to disappear off somewhere under the throttle body/ manifold. Doesn't appear to plumb back into the inlet pipe at all.
Can see the crankcase vent that you've pointed out but not sure if I remember it having two take-offs? Will check. Presumably you leave one going straight to the PCV valve so I don't have to muck about with that at all?
Last thing, and sorry if this was mentioned on the other thread - I got confused LOL:
If the rocker cover vents serve two purposes - i.e. as a source of clean air to replace contaminated air being drawn out of the crankcase vent, AND actually serving to vent out to the inlet pipe themselves at times, how does this work once you lose the inlet pipe connections?
And the very last thing - I do want to be green, seriously. I recently put in a 'sports cat' downpipe rather than a decat. How does the system work if I want to feed the vapour-free gas back into the engine? Could I use a tank simply as a remote interception system rather than an open catch tank?
#10
Nick:
Firstly, I did all my mods after the inlet was put back onto my car, thus my 'circuit' is based on access as much as trying to use the original plumbing.
If you look/try you will be able to use quite a bit of the original (the parallel fuel mod is the same) if the inlet is off the engine.
My engine is the Sti V3 my 1997 facelift, and I bet some engines are different in detail, ie UK turbo v Sti V3.
The second engine take-off is adjacent to the pipe to the inlet valve and esy to get at with the TMIC off and the inlet in place.
You are correct; leave the pipe to the valve completely alone.
Green!?
Yesterday I put my old sports cat back on!
Also, this mod has been on my car now for 4000 miles or so. There is NO oil in the catch tank or the TMIC. This must mean that there is no air borne oil mist in the 'air' vented from the engine to the system.
I have not thought about recycling the air back to the engine so won't comment.
I have never looked at the Impreza as a green machine, but it should be as clean as it can be.
Graham.
Firstly, I did all my mods after the inlet was put back onto my car, thus my 'circuit' is based on access as much as trying to use the original plumbing.
If you look/try you will be able to use quite a bit of the original (the parallel fuel mod is the same) if the inlet is off the engine.
My engine is the Sti V3 my 1997 facelift, and I bet some engines are different in detail, ie UK turbo v Sti V3.
The second engine take-off is adjacent to the pipe to the inlet valve and esy to get at with the TMIC off and the inlet in place.
You are correct; leave the pipe to the valve completely alone.
Green!?
Yesterday I put my old sports cat back on!
Also, this mod has been on my car now for 4000 miles or so. There is NO oil in the catch tank or the TMIC. This must mean that there is no air borne oil mist in the 'air' vented from the engine to the system.
I have not thought about recycling the air back to the engine so won't comment.
I have never looked at the Impreza as a green machine, but it should be as clean as it can be.
Graham.
#11
Nick
About being green..As you can see in Grahams drawing, even in the standard system, the gasses ultimately vent to atmosphere.
You might want to read this comment on Andy Forrest's site where he makes this comment on breather systems.
"The return of gasses from the catch can is also the subject of some debate. If the gasses are reintroduced to the intake system then you are asking the engine to burn an oxygen free mix ! ie you are reducing slightly the amount of oxygen fed into the engine, this can only mean less power. I personally prefer to vent to atmosphere and block off the return to the intake system. There are concerns that this is not very 'green' however the vented gasses are just of the same constitution as your exhaust gasses (assuming you have a decat exhaust)"
About being green..As you can see in Grahams drawing, even in the standard system, the gasses ultimately vent to atmosphere.
You might want to read this comment on Andy Forrest's site where he makes this comment on breather systems.
"The return of gasses from the catch can is also the subject of some debate. If the gasses are reintroduced to the intake system then you are asking the engine to burn an oxygen free mix ! ie you are reducing slightly the amount of oxygen fed into the engine, this can only mean less power. I personally prefer to vent to atmosphere and block off the return to the intake system. There are concerns that this is not very 'green' however the vented gasses are just of the same constitution as your exhaust gasses (assuming you have a decat exhaust)"
#12
Yes well as Graham said, an Impreza is never going to be a green way of getting about, but I feel it's my duty to at least do my bit to keep my emissions down. Maybe it's my penance for years of running decatted motors that popped and flamed on every gearchange LOL. I've had my fun.
I've seen Andy's comment but he is working on the principle of a decatted exhaust system which I do not have. As I've gone to the effort (not to mention expense!) of a sports cat system, I want to plumb the oil free gas back in to the inlet even if it does mean a slight loss in power. I can handle that.
Thanks to everyone's drawings, pictures and explanations, I can finally see where everything needs to go. I'm planning to to run the crankcase vent pipe (that normally runs to the inlet pipe) across the engine bay in 1/2" hose to an unvented catch tank with steel wool in it. This will have an outlet for 1/2" hose to run back across to the inlet pipe. I'm leaving the two rocker cover pipes connected to the metal T-pipe under the manifold. The only dilemma is whether to:
a) Insert another PCV valve into this line to prevent any venting of rocker cover vapours into the inlet but still allowing fresh air to be drawn into the rocker covers?
b) Run the rocker cover breather system through the catch tank as well?
Opinions?
I've seen Andy's comment but he is working on the principle of a decatted exhaust system which I do not have. As I've gone to the effort (not to mention expense!) of a sports cat system, I want to plumb the oil free gas back in to the inlet even if it does mean a slight loss in power. I can handle that.
Thanks to everyone's drawings, pictures and explanations, I can finally see where everything needs to go. I'm planning to to run the crankcase vent pipe (that normally runs to the inlet pipe) across the engine bay in 1/2" hose to an unvented catch tank with steel wool in it. This will have an outlet for 1/2" hose to run back across to the inlet pipe. I'm leaving the two rocker cover pipes connected to the metal T-pipe under the manifold. The only dilemma is whether to:
a) Insert another PCV valve into this line to prevent any venting of rocker cover vapours into the inlet but still allowing fresh air to be drawn into the rocker covers?
b) Run the rocker cover breather system through the catch tank as well?
Opinions?
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