View Full Version : crankcase breather options

03-19-2007, 04:41 PM
this pro street 57 has issues with excessive crankcase pressure....resulting in oil leaks from the front seal(so far) its running a breather in each valve cover, with no pcv...as ther is no source of vacuum that doesnt directly affect the IAC. anybody got any ideas short of running an evac system into the exhaust?

03-19-2007, 05:38 PM
I'm having the same issues with my 540 thinking of a electric vacum pump
but what I would really like is a morroso vacum pump but do not know if I can make it work with my March pully system maybe someone on here has?

03-19-2007, 05:50 PM
this pro street 57 has issues with excessive crankcase pressure....resulting in oil leaks from the front seal(so far) its running a breather in each valve cover, with no pcv...as ther is no source of vacuum that doesnt directly affect the IAC. anybody got any ideas short of running an evac system into the exhaust?

I'd try a pair of remote breather tanks like the Mule and Malitude have. Basically they can be mounted hidden or in the open, look like overflow tanks with a breather on top. One #10/12 line from each cover to the remote tanks. They make aluminum ones or the plastic tanks from Jaz, etc.

If it still has too much pressure in the crankcase there's an engine issue at that point.


03-19-2007, 08:14 PM
If it still has too much pressure in the crankcase there's an engine issue at that point.

this wouldnt suprize me at this point, but i will look for the breathers.

03-20-2007, 12:23 PM
Had the EXACT same problem with my newly built, supercharged 388. I went to a Stef's evac. tank on the firewall with one -12 line coming out the top of the valve cover.


problem fixed!!!

03-27-2007, 12:52 AM
Is stuff coming out of the breathers? If not, it sounds to me like you've got something plugged between the top and bottom end of the engine.

03-27-2007, 07:21 AM
Run an evac set up. I had a similar problem on an old nitrous motor combo, was blowing oil out all over the place. At first I thought I just had lots of leaks but realized it was being pushed or forced out. Weld tubes to your headers near the collectors and run lines from the breathers. This does pull a vacuum and will help pull crankcase pressure out. Just be carefull to check that its not pulling alot of oil out or you will have a mess. I put a catch can between the header tube and the valve cover breather tube to collect oil with no breather so it didnt lose the vacuum at the first breather or atmosphere source.


03-28-2007, 09:40 PM
I am going with 2 syclone/typhoon pcv valves. Inline I'm using Jegs oil seporators and one way check valves. One valve is plummed to the stock area under the carb. The other is going into the intake pipe for the Procharger. The Syclones use the exact setup, without the check vavles or seperators. The setup from GM works O.K. except for oil consumption. Hopefully when I get my carb and get it running it'll work good.

03-31-2007, 12:43 AM
i got a couple remote mount breather tanks from jegs, if the problem doesnt go away, then the next step will be evac the breather tanks into the x pipe right behind the collectors(hpc coated headers are harder to "touch up" than the stainless exhaust)

05-20-2007, 03:38 AM
ok, another 200 miles after installing the remote breathers and it seems to have cured the problem.

the deal was kinda strange, throw a new set of breathers on and everything was fine, but after a couple days of driving the breathers became oil saturated(sp) and no longer "breathed". my "theory" is the remote breathers (mounted about 4' away) gives the atomized oil a chance to re-solidify before ever making it to the breather tanks. i did drain the tanks just to see if there was any oil accumulation, but found nothing more than a lil condisation moisture.... which seems "normal".

so there ya have it, so far so good, thanks for the input/suggestions.

05-26-2007, 03:47 PM
I was thinking of making my own breather tank, (7"x4") and running both lines to one tank. Will this be good enough? It would have one breather filter on it. I was also thinking of making the bottom drain back into one of my turbo return lines. Anyone have any thoughts on this??

Also, does anyone make something to convert a regular breather hole, on the valve cover, to accept a -12 hose? I have some really nice billet valve covers from Speed Inc., and dont want to weld on them.

Thanks - Ron

06-10-2007, 02:55 PM


06-10-2007, 03:45 PM
does anyone ever wonder why there is so much preasure? this seems to indicate 2 problems. 1 being ring seal (ie) blow-by. And second . with proper baffling there shouildn't be much oil getting in the breathers . if there is that much oil i would start to wonder why it isn't draining back, or is there just too much oil getting up top. i can see some preasure biulding up under extreme situations such as turbo or nos motors. but even then it's stiil a cylinder sealing issue. under normal driving conditions crankcase preasure should be minimal. i'm not trying to be a wise guy ,but i would try to solve the problem rather than put a band-aid on it.

06-16-2007, 09:24 AM
From my understanding, when forced induction is used, there will be some blow by. Im not trying to cover up a problem, Im trying to advoid one. I havent built the motor yet. Im in the mock up stages. I just dont want to have oil vapor/oil on my valve covers. I would rather have something to catch the oil (if there is any) and return it to the engine, instead of having to clean oil off my billet valve covers every week.


06-17-2007, 01:56 AM
I think your breather design would work, but it seems like overkill. If you put proper baffles on your valve covers, the only think coming out of the covers will be a little vapor. If you condense this, you'd only get a few drops. Is this a race type setup that doesn't allow ordinary breathers? That's what I run and there is no condensation at all on my covers, and no visible vapor at all.

06-17-2007, 08:17 AM
This is a street set-up. I have seen people with open filters that drip oil after running it hard. I dont like the idea of oil on my valve covers or smoking because it driped on my headers. Right now I have Billet "closed" type breathers. Im not sure they will vent as well as I need. I like the "race" type look that the custom beather tank will provide. Will one "open" breather be good enouhg to vent all the gases ok? Also I thouhgt it would be nice to have the tank drain back to the oil pan. I was going to put a "T" between the oil pan and the turbo oil return line. Will I need a one way valve in the line between the breather tank and tee? Also, what can I use in the vave covers to run the lines to the tank? I dont want to weld on my valve covers, so I want something that will either bolt to them (in the original holes) or push in the rubber gromet.

Thanks - Ron

06-17-2007, 11:53 PM
What are closed type breathers? Isn't that an oxymoron? :)

Is the turbo return line an unpressurized gravity line? If so, you could probably tee into it. One breather should be plenty. If the turbo line is pressurized, teeing into it might cause oil to fill up into your vapor tank. You'd need a check valve in the tank line in this case.

Do you have baffles under the covers to prevent direct splashing of oil onto the bottom of the breathers? Here's a picture of mine. With this setup, there is no dripping of oil, no matter how long you drive.

If you still want a catch tank, using a rubber grommet, you can run a setup something like this. No need to weld on the covers. Use an PCV valve connector to fit into the rubber grommet, and connect it to your tubing. I know this guy has a breather setup, but you can see the right angle connectors from the valve covers as an example.