Thread: crankcase venting

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Here's a question. Is it bad to not be running a pcv valve? Right now I just have one breather on each valve cover. Just simple push in breathers. No hoses... Does this harm anything? Is a pcv valve a must? I don't think it is unless you're trying to pass a smog test but who knows??!

This is a common question from younger folks who dont remember the "road draft tube" engines before the Positive Crankcase Venelation arrived. There is an amount of vapor created in the crankcase.....older engines with worn rings and cylinder walls have more blowby. In the old days, the oily vapor was simply routed out of the engine by a tube. This road draft tube usually hung down under the car so the vapors would get blown away as the car ran down the road. The tube had some mesh in it so that the oil would condense and maybe go back into the engine. Those cars didnt rust underneath since they had a nice coating of oil on their underside.

Your engine without PCV is the same.....no matter how tight it is there will be vapor escaping and the valve covers will have a nice oily film on them......if you dont care, the system will work.

However, it is so easy to install a PCV, a clean engine compartment is simple.

Hmmmmm, now that you mention it.......Yeah, there is a small oily film on the valve covers. Thanks! Makes sense....

what if your running valve covers with no breathers.....possible probems??????

Originally posted by 47fordCOE
what if your running valve covers with no breathers.....possible probems??????

you got to have some kind of a breather. 2 push-ins well work, people use them all the time on round tracks at over 6000 rpms. to do it right you need to install a pcv system.


http://www.clubhotrod.com/forums/att...&postid=100112

I'm running a 327 chevy (64) with the old breather in it. It1s10 is right ya gotta run some kind of breathing system. I saw a pic of someone who ran a pipe between valve covers with one big breather right over the water neck ! ! Whatever works ! !

Originally posted by 47fordCOE
what if your running valve covers with no breathers.....possible probems??????

I had a '57 Ford custom after coming back from overseas in 66. To pass emissions in So. Cal. they plugged the 292 up in an attempt to instal a pvc system. One night it built up so much pressure it blew the dipstick out, put a dent in the hood and covered the passenger side of the windshield with oil. Shortly thereafter the bearings were toast. Engine has to breathe.

Moisture and acids, the byproducts of combustion, have to be vented out of the engine or the bearings, etc., won't last very long. Put a PCV valve in one of the tappet covers, and a vented cap in 'tother, your engine will thank you for it.

I don't think you can effectively use the PCV valve in one valve cover with an "open" vented cap in the other. The PCV venting system only works when the engine breathes solely through the PCV valve.

hotshoe
"I don't think you can effectively use the PCV valve in one valve cover with an "open" vented cap in the other. The PCV venting system only works when the engine breathes solely through the PCV valve".

it has to be open somewhere else on the motor or you would suck every gasket you have out of the motor. this is the open and closed system. it has to be one or the other.

http://www.clubhotrod.com/forums/att...&postid=100112

still denny a closed system is not a system with the pcv vale in one valve cover and no openings anywhere else. on the closed system the other hose goes into the breather and circulate the air into the carb. breather. some of it get used over again and some goes out of the tail pipe, but its got to have a out let. i think some people belive a closed system would be just a pcv valve stuck in ome valve cover with no other opening. or am i reading it wromg?

I know this is an old thread, but the diagram really helped me out. Thanks a lot (if that member is still around). I am supposed to dress up my uncle's truck and didn't know what exactly I was replacing in the closed PVC system, now I understand and will hopefully get the right stuff.

Red

Denny, stand and take a bow.

Kudos to you both.....We love your work and efforts.

Some of you may find this interesting.

http://www.jalopyjournal.com/forum/s...d.php?t=184387