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Discussion Starter · #1 · (Edited)
I've been stalking corral.net for years, and always been able to find great info on whatever was getting me stumped- thanks everyone. Haven't signed up until today.

Here's my issue... I have a 2003 Mach 1 with a D1SC and a slow rear main leak that's been bothering me for a couple years. Just fed up with it and want to stop leaking for good. My evac system has gone through a few phases since the S/C install:

1) Both valve covers vented to atmosphere --> oil was sprayed everywhere underboost.
2) Passanger side valve cover vented; driver side hooked up to intake pipe before S/C with an air/oil seperator inline --> reduction in crankcase fumes, but did not draw a vacuum.
3) Current setup/untested: Passanger side valve cover hooked up to intake pipe before S/C; driver side hooked up to exhaust by way of EGR pipe (EGR is deleted) with a check valve inline.

I haven't driven the car, only idled in the driveway with the current setup. Seems to run smoother and not leak- but i have some concerns.... will my o2 sensor become contaminated over time because of the crankcase being evacuated through the egr pipe (which is about 8 inches before the o2)? Will my A/F ratio be thrown off because of the crankcase fumes traveling over the same o2? Will my MAF become contaminated over time because of the crankcase being evacuated through the intake?

Sorry for the long post, just wanted to make sure everything was as clear as possible. Thanks in advance for any input you might be inclined to give me.
 

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personally i think it'd be best to vent both sides to the exhaust, and after the o2. maybe shut the rear ones off in the tune and route some braided lines from the pcv boss to the rear o2 bungs.
 

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Discussion Starter · #3 ·
I like that idea- dont have to worry about contamination at all ...my rear o2 sensors are in fact shut off, so it would be as simple as routing some braided hose and fab a few fittings.

Do you think the exhaust system will draw a large enough vacuum that far back in the exhaust system? I though they were most effective near the header collector...

With the current setup the vacuum is good (albeit contamination prone), so I would need this setup to produce at least the same amount of suction. What do you guys think of this new idea?
 

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There have been a lot of posts about this on different forums. I'm running basically stock setup but I added a check valve between the manifold and PCV valve to keep boost out of the crankcase, and a JLT oil separator on the PCV side. I don't have any oil to speak of in the blower or manifold. Passenger side: PCV to check valve to intake manifold. Driver side: intake tube AFTER the MAF before the blower. I'm using an Eaton, but this is the same setup a Vortech uses.

You need some vaccuum to help the rings seal (thus a PCV valve or something to draw vaccuum). You also don't want unmetered air coming in after the MAF (like an open breather with a PCV valve). That will make your engine run lean. Make sure the driver side vent is AFTER the MAF. If oil hits the MAF it will read wrong and your motor will probably go boom. You probably also want the vent as far from the MAF as possible (close to the blower). I'm assuming you're using a draw-through MAF. With a blow-through MAF you want the vent tube after the MAF. Lots of opinions but mine works for me.
 

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Discussion Starter · #7 · (Edited)
Thanks for the replies. I think i have read just about every pcv type thread out there, but was still in doubt, hence the posting here. Any more opinions on the exhaust evac going through the rear o2 bungs? Enough vacuum?

65DOHCStang: I have a blow through setup running 18 lbs. Original setup on the car used the stock pcv hooked up to my manifold and the first time i went into boost, the pcv cracked. Similar to your setup... are you suggesting this with a high pressure check valve would work correctly in my situation? Where would the other VC hook into? Post MAF for me is under boost...

tireburner163: I though about your idea before, and although it would not create a mess in the engine bay, it also wouldn't provide me with any vacuum in the crankcase- which i need to stop the rear main leak. Thank you for your input, though.
 

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65DOHCStang: I have a blow through setup running 18 lbs. Original setup on the car used the stock pcv hooked up to my manifold and the first time i went into boost, the pcv cracked. Similar to your setup... are you suggesting this with a high pressure check valve would work correctly in my situation? Where would the other VC hook into? Post MAF for me is under boost...
With a blow-through setup you probably can't vent the intake side from the intake tube since you'll have boost after the MAF or pull oil into the MAF if you put it before the blower. Don't have any suggestions for that. Maybe vaccuum from the exhaust is the only option for blow-through. On another forum some guys were talking about an electric vaccuum pump some OEMs used with turbo systems.

I have a check valve between the intake manifold and the PCV that blocks pressure from getting to the PCV, since most PCVs will leak some pressure into the crankcase.
 

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Discussion Starter · #9 ·
If I run your VC --> PCV --> check valve --> manifold method alone, and cap the other valve cover, would this provide a suitable vacuum during all driving conditions? From my understanding: that setup alone will provide me with tons of vacuum at idle, some at partial throttle, and absolutely nothing at moderate or WOT when i need evacuation the most. This is why i was thinking to have the other VC hooked up pre S/C where vacuum would increase with rpm (possible with an air/oil separator)- that way idle/part throttle would be covered your way and moderate/WOT would be covered the other way.

Thoughts?
 

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tireburner163: I though about your idea before, and although it would not create a mess in the engine bay, it also wouldn't provide me with any vacuum in the crankcase- which i need to stop the rear main leak. Thank you for your input, though.

The rear-main seal leak is most likely being caused by excessive crankcase pressure due to the supercharger pressurizing the crankcase.


Did the rear-main leak with open breathers?
 

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If I run your VC --> PCV --> check valve --> manifold method alone, and cap the other valve cover, would this provide a suitable vacuum during all driving conditions? From my understanding: that setup alone will provide me with tons of vacuum at idle, some at partial throttle, and absolutely nothing at moderate or WOT when i need evacuation the most. This is why i was thinking to have the other VC hooked up pre S/C where vacuum would increase with rpm (possible with an air/oil separator)- that way idle/part throttle would be covered your way and moderate/WOT would be covered the other way.

Thoughts?
Yes, what you're saying is correct. Capping the other valve cover wouldn't provide any incoming air, so it would always be under vacuum, except at WOT. And with no inlet vent it might have too much vacuum. But at least you wouldn't be pulling unmetered air into the engine.

Putting the incoming air (vent) side before the blower will create a slight vacuum at WOT. The problem is with blow-through you will probably get some oily mist now and then which could contaminate your MAF and make it read wrong, and that could be disastrous. (Sean Hyland says he lost an engine with an early Vortech when a seal leaked and contaminated the MAF.) I don't know how to do this safely on a blow-through setup.
 

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Discussion Starter · #12 ·
Did the rear-main leak with open breathers?
Yes.

65DOHCStang: Thanks for the input, you've got my gears turning. I like the modified PCV setup for my driver's side. I think that will work nicely for everything but those WOT moments.

All: What are some ideas for evac at WOT? Exhaust evac like 'Guido in Da Cobra' suggested? I'm worried that will my full exhaust the vacuum at WOT would be negligible.
 

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Discussion Starter · #13 ·
Have been doing some more research and read some others having success with: PCV --> check valve --> catch can --> manifold; with the other VC vented to atmosphere.

This is essentially 65DOHCStang's set up sans the catch can (which i like). What has me confused is that this intentionally introduces unmetered air into the manifold by way of the VC filter. Can this be so slight that it doesn't make a difference? Is this well within the O2 sensor's range of adjustment? Would hate to make another trip to the dyno just for a minimal change in idle/part throttle.
 

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the exhaust is said to have enough vacuum as long as there isn't a chambered muffler in place. they sell exhaust pcv setup's which have a check valve in them that you attach to your exhaust pipes. supposedly old hot rods used to sometimes run these things, but nobody does it these days.

also do not leave one side connected to the intake and the other side plugged. i had this set up on my car and driveability suffered greatly. there would also be enough vacuum in the crankcase to force air through various grommets/gaskets and cause a belt slip sounding squeal at all times.
 

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Discussion Starter · #15 · (Edited)
Thanks for everyone's input and ideas... used that to tinkering with some different routing and setups last night and came to the conclusion in my head that the best evac method for me will be as follows:

Driver side VC --> stock PCV --> 30psi check valve --> lower intake manifold

Passanger side VC --> oil catch can --> power pipe before S/C

Idle, part throttle: The PCV system works normally.
Moderate throttle, WOT, boost: The check valve closes the driver side flow, passanger side is evac'd through catch can and into S/C.

This should cover all driving situations, although I realize the pre S/C vacuum will not be as significant and the manifold vacuum (but only place to still draw some vac during boosted conditions). I also realize this introduces a small amount of unmetered air into the manifold, but I should be able to tune around this.

Only other option to improve evac for my blow through set up would be a electric/mechanical pump- and I'm not going that route. Also chose against the exhaust evac because of my cats and muffler restrictions. Do you all agree with the above info and what I've come up with?

Thanks again for everyone's contributions.
 

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If you have the inlet on the power pipe before the SC you're still getting umetered air (a vacuum leak) and risking contaminating the MAF. You'd be just as well of with an open breather on that side, and not risking MAF contamination. It's the blowthrough setup that is creating the complications. Can you switch to a pull-through MAF before the SC?
 

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Discussion Starter · #17 · (Edited)
Not without quite a bit of fabrication and a re-tune.

I think at this point I'm less concerned with the unmetered air (which hopefully I can tune around) than the fact that I would like to have an active evac while I'm in boost.

Here's a thought. What if I ran the passenger side VC to atmosphere like 65DOHCStang posted, but kept the driver side VC set up as described above? This would give me good evac and fresh (yet unmetered) air in all conditions except heavy throttle/WOT. But, because the passenger side is now vented, wouldn't the excess pressure just push out the breather once the check valve on the other side closes? In other words, the crank case vapor wouldn't be under vacuum at WOT, but it wouldn't be trapped either.

I hope all that made sense... I don't think this is ideal, but is it an acceptable method given the car's setup? Will it alleviate my original blow-by issue?
 

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Discussion Starter · #19 ·
Just signed up and browsed through a few of the posts. Found a thread with a similar type problem of running a functional PCV system with a blow through MAF. The solution is outline in detail; the link is below for anyone curious. Thanks for everyone's help... especially 65DOHCStang.

click here
 

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Discussion Starter · #20 ·
Update: Got everything installed, set the crankcase vacuum to 10 hg inches. Have only let the car idle in the driveway with small throttle blips, but no sign of any more rear mean leakage. With throttle, the vacuum naturally dips down, but seems like it should maintain at least 4-5 inches under part throttle. Not sure about boost... by design should just be atmopheric pressure, hoping it won't go into the positive PSI.

Question, is running 10 hg inches at idle so much as to not allow the engine to oil properly? Should i raise the vacuum or decrease it or keep it where it is? It's doing its job keeping the rear main seated, but what about the long term effects of running that amount of vac on the crankcase? Thanks in advance.
 
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