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Do I Need A PCV Valve?

ObscureMachine

Seatbelt Orifice Officer
Joined
Sep 28, 2006
Messages
3,998
Loc.
World Headquarters
My bronco didn't have one when I got it, just a breather vent on the valve covers. Do I need one? Will it help anything? I'm going to buy some bronco valve covers and was wondering if I should add the pcv valve. BTW - I have an edelbrock 4bbl carb.

Thanks!

JiM
 

Viperwolf1

Contributor
electron whisperer
Joined
Aug 23, 2007
Messages
24,316
Yes you should. It gets rid of unburned fuel and moisture in the crankcase and can prevent oil leaks from excess pressure.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,835
As mentioned, it should have one. The biggest issue is removing excess moisture. Byproduct of combustion is water. Rings do not seal perfectly, if they did we wouldn't need a breather. So a little combustion gasses get into the crankcase. Condense in the oil and contaminate it. It also gives a touch better mileage as the unburned blowby gets a second chance to be burned. There really isn't a good reason not to run one on a street engine. PCV in one valve cover, some form of breather in the other.
 

ken75ranger

Bronco Guru
Joined
Jan 27, 2002
Messages
5,069
Loc.
Troy, NY
If you don't have a pcv valve the fumes aren't actively getting removed. If you don't pull the fumes out I'd double up on the oil changes. It ends up being cheaper and better to put a pcv valve in.
 

Dave

Contributor
Bronco Guru
Joined
Aug 25, 2006
Messages
2,190
I agree with everything above. Make sure the inlet side is filtered as it will be drawing more air through the engine and you don't want dust sucked in. Most stock systems have a hose that pulls filtered air from the airclean housing. I also cuts down on some nasty smells.
 

Nobody

Bronco Guru
Joined
Feb 15, 2005
Messages
1,215
Loc.
Stanwood
My 5.0L was smoking a bit after I got it running, which was odd because it was fine in the donor car. I discovered the PCV valve had popped out the lower intake when I installed the engine. Plugged it in and the smoke was gone. Without the PCV, it was building excessive crankcase pressure and forced the oil past the valve seals/rings.
 
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