valve cover vent?
#1
08-27-2008, 12:43 PM
valve cover vent?
I tried to search but I donteven know what this thing is called so Im sorry if this has already been covered. On the valve cover (drivers side) on my 1986 2.8L engine, there is a hole with a tube coming out of it which connects to the intake manifold. What is that called? and what is its purpose?
#2
08-27-2008, 01:55 PM
RE: valve cover vent?
Positive Crankcase Ventilation valve and corresponding tube. The PCV valve opens with crankcase pressure to vent the pressure, directing it into the intake so that the entrapped oil and combustion byproducts do not exit the system before being burned up.
#4
08-27-2008, 04:04 PM
RE: valve cover vent?
The PCV valve will have a vacuum source off of the intake manifold itself. The vent for the crankcase will have just a tube that runs from the valve cover to the air cleaner (intake duct in the case of the CPI) so it can pull in fresh, filtered air.
#5
08-27-2008, 05:44 PM
RE: valve cover vent?
??? im very confused. My PCV has a direct line to the TBI, not the intake manifold. The direct line to the air cleaner is what Im talking about. I wasnt even sure if that is where it was supposed to go. I need to replace that line. Is it supposed to be just pushed into the hole, or should there be a fitting on the valve cover that it connects to?
#6
08-27-2008, 08:44 PM
RE: valve cover vent?
Yeah, what I meant was the intake under the throttle blades. That sees manifold vacuum so it could either be in the intake itself or to the TB like yours is. My old '85 S10 2.8L had it go into a fitting just below the feedback carb.
You can take the vent which goes into the filter housing and just put its own small filter onto it.
You can take the vent which goes into the filter housing and just put its own small filter onto it.
#7
08-28-2008, 10:34 AM
RE: valve cover vent?
ORIGINAL: swartlkk
Yeah, what I meant was the intake under the throttle blades. That sees manifold vacuum so it could either be in the intake itself or to the TB like yours is. My old '85 S10 2.8L had it go into a fitting just below the feedback carb.
You can take the vent which goes into the filter housing and just put its own small filter onto it.
Yeah, what I meant was the intake under the throttle blades. That sees manifold vacuum so it could either be in the intake itself or to the TB like yours is. My old '85 S10 2.8L had it go into a fitting just below the feedback carb.
You can take the vent which goes into the filter housing and just put its own small filter onto it.
#8
08-28-2008, 10:48 AM
RE: valve cover vent?
If the PCV valve is not operating correctly, this can happen. This vent should only be there to allow the air into the motor. Also, when using a filter for the vent, you should make up some sort of baffled tube for the air to travel through so the oil has a chance to get out before it gets to the filter material.
#9
08-28-2008, 09:29 PM
RE: valve cover vent?
Stock valve cover (with baffle) and had new PVC valve. I at first thought that might have been it also.
Prolly just blowby on a motor with 200+k miles on it. Still not a big fan of the filters.
Prolly just blowby on a motor with 200+k miles on it. Still not a big fan of the filters.
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