Crankcase Ventilation

[greenXpress]

New problem. I am getting condensation collecting in my valve covers. I did not plumb in a pcv valve and would rather not have one. I drive the truck almost every day, but it does not have time to get very warm. Some of the drivers are less than 2 miles. Not sure if a header evacuation system will work on the street. The problem just shows up during cold weather, but I don't really want the truck to be a "fair weather" ride only. Any ideas?

[Bamfster]

Why no on the PCV valve?

[TheSilverBuick]

Why no on the PCV valve?

That'd be my question too.

[AFFORDILLAC]

I would never want to introduce hot crankcase air to the intake ever again... jus add breathers.

[quick 52]

Are you using synthetic oil they pick up moisture if not run up to temp

[greenXpress]

Are you using synthetic oil they pick up moisture if not run up to temp

I have two 3" X 4" can type breathers that have a shield half way around. I do not really want to run crankcase air back through the intake. I run 15-40 Rotella in everything I have. Not the synthetic type.

[squirrel]

I'd rather run the yucky crankcase air into the intake, then leave it in the crankcase where it will really screw things up.

[greenXpress]

I'd rather run the yucky crankcase air into the intake, then leave it in the crankcase where it will really screw things up.

Are you guys running pcv valves? I guess that is what I should have asked. And do you have a daily driver?

[Bamfster]

I've always run one, plumbed into the back of the carb base. No moisture in the crankcase, no icky oil mist on the covers .... no problems what-so-ever.

[TheSilverBuick]

I run them on all my cars, including the Skylark.

[dave storlien]

Lets look at how a PCV works and you decide what you want. Ok a PCV system works off of engine vac. and at idle with high vac.and no load or under low rpm load the cylinder pressure is low and so is the blow bye. So when you don,t have blow bye it works , at full throttle under full load with high blow bye when the engine has little vac. when you need breather the PCV does not work. It will evacuate the crankcase when the engine has high vac. as it comes back to low load and low blow bye. In your case with short trips it will help . But it does mess with carb tuning because you have a Vac leak. GM does make a electric Vac. pump. I have used them and work very well. Good luck

[CDMBill]

Cool, Dave Storlien in the BS House. There is a bit of bright line between street setups which should have a PCV system with the associated tuning and oil contamination issues and more serious race motors on the street e.g. Drag Week engines where tuning is a bit on the edge as pump gas meets higher than conventionally acceptable static compression ratios and therefore requiremtight control over AFR at all operating conditions. My solution is a Peterson external oil pump with two scavenge stages that create around 5" of crankcase vacuum at cruise rpm's and loads and they exhale through two Jazz breather tanks.

I use a Star Machine adjustable vacuum break to limit crankcase vacuum to 12" max under WOT to avoid drying out the wristpins. The crankcase vacuum allows me to run a slightly narrower ring package with highly effective sealing and oil control.

PCV's cicuits are tunable by using different spec OEM valves and paying attention to the line size and fitting sizes so that you get exactly what you want for crankcase/valvecover effective pressure without excessive combustion chamber contamination.

[MR P-BODY]

A header e-vac can work on the street BUT there are a couple of things to keep in mind...
first is the fact that it will only pull about 5"hg... but thats at revs... next is the exhaust
back pressure... if the exhaust has greater than 5"hg of back pressure it will start backing
up the pressure to the point that it burns out the check valve and starts to pressurize the
crank case.... even if you dont have 5"hg of back pressure you will get very little help from
the e-vac due to the lack of flow going across the tube(in the collector)... they tend to work
fine when its a WOT... myself I would either set up a GM elec vac system or use the PCV or
both and run the elec one at the track and use the PCV on the road.... but you really need
to warm that engine up .... way longer than 2 miles(with all the condensation you build up
in the entire engine and exhaust you are killing it without even knowing it)
EDIT
Also.. for every inch of back pressure you decrease the vac that the e-vac
will pull.... max vac is 5" so if you have 3" of back pressure you only have
2"hg of vac

[CDMBill]

I ran a header evac, vac-u-pan set up years ago with a Dodge truck breather with a welded on GM PCV and at a GM anti-backfire value on the tube at the collector which worked pretty well, but it needed a very free flowing down stream exhaust. That consisted of straight pipes to mufflers and turndowns at the axles. LOUD.

[squirrel]

Are you guys running pcv valves? I guess that is what I should have asked. And do you have a daily driver?

Now you're asking the right questions

I have what you might consider a daily driver....sort of....over 100k miles on the motor in a bit over 20 years. Just a PCV valve on one side, and a crappy chrome breather on the other. But it's just a mild 700 hp blown big block