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Discussion Starter #1
I always see this mod on the old NA muscle cars and the breathers are usually cheap. I'm just not sure what the mod accomplishes and if it would be worthwhile on our near-stock saabs (or highly modified for that matter). It seems there is already the hole there, but it's got a line off of it. Any input/ warnings?
 

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The only problems you will run into is an oil smell in the engine compartment as you would be venting the oil filled air instead of recirculating it bakc to the intake and your breather filter would eventually get very oily and potentially reduce the amount of breathing of the crankcase.
 

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I have had a crankcase breather on my car (99 9-3) for a while now and I'm not getting any oil coming out-I still have the other hose with the check valve in it connected to the throttle body and the end that used to go to pre compressor has the filter on it.I remember looking at ERP's and he was losing oil through his so I don't know why mine would be different bu tI have had no problems with it.
 

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On some cars with turbocharged engines, oil in the intake sort-of does the same thing as lower octane gas. The ecu compensates by changing the timing, and/or reducing the boost (a tiny amount). I think T5 does that, not sure about T7. Does not matter much if running stock boost levels, it is a tiny effect. Some people notice when running boosted up (mbc etc) or chipped cars. Usually on a gear change, or boost being up and then down a bit within seconds. Like heat soak, but sooner. You have to have a lot of oil though, whether from the crank case or from the compressor seal to notice, or measure it on a dynamometer.
 

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it's not just having oil in the intake...

mixing oil with gas DOES lower the octane rating.
if you have enough oil that you're sucking it into the motor, you should do something about it. most people put an inline Filter between the PVC and return line.

if you had enough extra hose, you can Do the Same.
 

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Works on Cossies with lots of blow-by. This is my catch tank on Saab.
 

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Kept it. This bit goes between the rocker breather outlet and the vent to the turbo intake pipe.

Also got some nice braided hoses now I know that PVC goes squidgy when hot :D Slippery when wet? Something like that.
 

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SPATL said:
The only problems you will run into is an oil smell in the engine compartment as you would be venting the oil filled air instead of recirculating it bakc to the intake and your breather filter would eventually get very oily and potentially reduce the amount of breathing of the crankcase.
That's not the only con of not having the breather.

Pros of not running PCV into the intake: 1) Higher effective octane, 2) Less plumbing in the engine bay

Cons of not running PVC into the intake: 1) Valve stems tend to not seat as well and you burn more oil. 2) If you have an emissions inspection where they check under the hood, you will fail.

I generally regard having PCV as a good thing, but if you don't have a catch can you should get one. It will keep most of the oil from going into your intake, and it's emissions legal to instal a catch can as long as you still route PCV fumes to the intake.

There is another solution which some Subaru people have tried. That solution is to use a smog air-pump to pump to generate the vacuum to seat the valves. Usually you route it to a catch can first, then the smog pump, then just to a filter into the engine bay. That way you don't get effectively lower octane by putting oil into the intake and you still seat the valves. :)

Adrian~
 

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Discussion Starter #10
So, correct me if I misunderstood, but there is some nasty oil/vapor coming out of the hole. Stock: it is recirculating into the intake. With Breather filter: It is going into atmoshpere, maybe even spilling out through the filter (perhaps being counter-productive if you don't keep an eye on it). Run some plumbing to a reserve tank: which you would only have to drain occasionally. Sounds like an affordable mod, only engine mods I have are MBC and some intake/intercooler upgrades. Thanks for the advice.
 

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95turbo said:
So, correct me if I misunderstood, but there is some nasty oil/vapor coming out of the hole. Stock: it is recirculating into the intake. With Breather filter: It is going into atmoshpere, maybe even spilling out through the filter (perhaps being counter-productive if you don't keep an eye on it). Run some plumbing to a reserve tank: which you would only have to drain occasionally. Sounds like an affordable mod, only engine mods I have are MBC and some intake/intercooler upgrades. Thanks for the advice.
A catch-can is not a "reserve tank"; it drains any oil particles back to your oil-pan through a hose at the bottom rather than just storing them, and the vapors continue on to your intake and get burnt. Better than just a reserve canister. :)

It doesn't completely solve the problem of lower octane from PCV fumes, but it helps a lot by keeping most of the oil-droplets from making it back into the intake system!
 

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hunt.dogshome said:
Kept it. This bit goes between the rocker breather outlet and the vent to the turbo intake pipe.

Also got some nice braided hoses now I know that PVC goes squidgy when hot :D Slippery when wet? Something like that.
Yeah, noticed that <chuckle>. I think squidgy is the correct rechnical term... I am using 4.8 mm fuel line, reinforced. Has worked ok for two years.

I wonder if you could go from the valve cover to the catch can, then two lines from there, one to the intake, one to the throttle body through a check valve (?)
 

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PMI said:
I wonder if you could go from the valve cover to the catch can, then two lines from there, one to the intake, one to the throttle body through a check valve (?)
I wouldn't bother with the two lines from there. I'd leave the TB to check valve to Nipple in place and go from the larger side of the nipple to the catch can and then catch can to hardpipe.
 

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I was considering using a PCV setup for turbos I read about that uses two check valves. The line that goes to the manifold is unchanged and a second check valve is added to the larger bypass line before it vented. This is the line that goes to the turbo intake on the standard configuration. Using this new setup, the crankcase only vents to atmosphere when the turbo is on boost. The rest of the time it still goes to through the smaller line to the intake manifold.

I decided not to use the above setup to be legal and friendlier to the environment. I ran the lines for my catch can from the valve cover to the can and then back to the nipple (which is now removed). Its a nice setup that is closed so I don't get any oily smell. Oil loss through the PCV is supposed to be prevented by a baffle near the exit hole of the valve cover. I expected to see both oil and water in the catch can but it mostly water. Isn't water in the intake supposed to be a good thing anyway?
 

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GaryG said:
I expected to see both oil and water in the catch can but it mostly water. Isn't water in the intake supposed to be a good thing anyway?
I think it just means there is condensation in the catch can, same reason why there is water condensing in the exhaust.

It is not a great system, the 9-5 models have a lot of problems with oil consumption, even after trying to reduce it with oil catch cans draining into the sump. Fixes have been tried drilling out the hole sizes etc.

Part of the trouble is that when there is vacuum in the throttle body, there is a small open line to the nipple, and from there a bigger open line to the intake. So you really can't tell where the vacuum is sucking air from, depending on relative pressure before the turbo, the valve cover, etc.

A second check valve would seem to fix that, but might screw up something else. I don't know how you could figure it out w/o multiple pressure gauges (the industrial kind, not the boost gauge type). And the pressure in the crank case changes with wear on the engine, too.

Not sure about the baffle... If the baffle is at the valve cover, where is the small line?
 

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Thought about 2 check valves, thus removing the permanent vacuum leak - ish. I guess the intake to the turbo has some vacuum as well. Gauges.....

But then what happens when the engine is stopped and cooling? Air can't get in either check valve to replace that which is cooling and causing vacuum. Perhaps it would suck the crankshaft seals in or something equally nasty (maybe not, but...)

Car has got very low oil consumption, but there is oily gunge in the hard pipe to the turbo.

Gearbox is preventing further testing of the catch can at the moment. Got company diesel Peugeot. Groan. Getting blown away by Mercedes Sprinter vans and ASDA lorries is no fun: "I'm going as fast as I can, I'll get in the inside lane as soon as I've got round this 18 wheeler ALRIGHT!!!"
 

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hunt.dogshome said:
But then what happens when the engine is stopped and cooling? Air can't get in either check valve to replace that which is cooling and causing vacuum. Perhaps it would suck the crankshaft seals in or something equally nasty (maybe not, but...)
Funny... stopped, meaning ignition off? I would think something is always open to the intake or the exhaust... not ALL the valves can be closed tight at one time, or are you thinking of something else?

Makes you wonder why the 9-5 has all those oil consumption and related problems, the engine is similar... some people are starting to blame the oil pump, but that seems like a stretch.

I would like to hear from someone who measured the oil collected in a closed catch can over a few hundred miles. And I mean oil, not condensed water. Part of the problem with the open drain cans is obviously the condensation, which does not belong into the sump any more than oil belongs into the intake... can't be the only issue though <shrug>
 

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Discussion Starter #18
The oil catch can seems like it's a great idea for a full time mod, no matter how you do it. But could there be much harm in just replacing the line that goes from the crank case to the TB with a filter for just a night at the track? or perhaps both lines with the filter?
 

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95turbo said:
The oil catch can seems like it's a great idea for a full time mod, no matter how you do it. But could there be much harm in just replacing the line that goes from the crank case to the TB with a filter for just a night at the track? or perhaps both lines with the filter?
No harm. Some people drive with a broken hose for months and do not know it. The open lines have to be capped, otherwise there is a vacuum leak and/or an unfiltered line into the intake.

You could unplug the connector to the purge valve while you are at it, and plug it back in later. I am sure that does not do you much good on the track, either.
 
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