All,

I have a 1986 F-150 302 EFI.
Today I was under the hood and noticed that my PCV valve was not connected to the manifold. I have owned the truck for almost two years and do not know how long the PCV was out of the manifold. I am no mechanic but I was looking at my Haynes Book and online and reading about what the system does and wondered if any damage might have been done with this system not working as it should (and who knows for how long). I did notice a little bit of oil in the air filter housing when I took it off. Could this be related or a coincidence?

I plan on getting a new PCV valve and inserting it into the manifold.


This is what I am talking about.

 

You're really just looking at getting dust and dirt and debris in your valve covers, that side lets in fresh air, the other schedules when it goes back through the combustion process with the rest of the emissions.

 

Well, the PCV valve should suck the blowby gases out from the crankcase but I'd imagine you'll be OK if the engine is mechanically in good shape.

 

Without the valve being installed in the grommet, you have no crankcase ventilation.

When you insert the valve into the grommet, is it a fairly tight fit to whereas excessive pressure will not blow it out?

Maybe a new valve and grommet.

 

Take your oil cap off and look underneath it. If it has a bunch of gook under it, that is caused by the PCV system not working. Nothing you can do about it now except hook it up and drive on. If it was really bad you probably could smell it in the cab some when sitting still at a stoplight.

If the valve rattles when you shake it, and it sucks on your finger when it's out of the valve cover and the engine is running, then it's ok, stick it in the valve cover and keep and eye on it.

 

Yep that's what I would do and if it pops out again new grommet
Dave ----

 

Ok, looks like I jumped in here with the wrong memory, I was thinking there was a grommeted port on either valve cover, and the air clean hooked to one for fresh air(instead of going into the oil fill cap) and the other had the PCV. I was thinking that looked like it was an air cleaner above it and this was the fresh air side. Really not sure what I'm looking at right now lol

I can't tell if you're joking or not, saying the crankcase won't vent out the large hole in the valve cover left by the PCV being unplugged... I'm gonna just assume you are though.

 

a$$-u-me

It will vent alright. It will release blow-by crankcase fumes directly into the atmosphere and the crankcase will not be vented resulting water vapor and the blow-by creating acids and sludge that will eat engine components and hinder proper lubrication.

The crankcase has to be vented by partial vacuum, whether road draft or PCV.

 

I'll argue that it's still vented, just not vented the best way possible. It was directly vented prior to road draft tubes which were made functionally obsolete by vacuum operated systems.

 

Not to start a food fight, but you need to read a text on CCV.

Road draft was replaced because of EMISSION LAWS. An open crankcase is causing pollution, engine damage, against Emission Laws and not too bright.

Now go ahead and call me a no good SOB know-nothing and get it vented out of your system.

 

So... You're telling me a hole in the valve cover doesn't vent the crankcase unless you suck on it?

 

Correct ...

Let me qualify that. By introducing a partial vacuum. I don't go for that sh!at.

 

I'm going to say you're wrong and I'd even go so far to say that if you left the pcv valve out of the valve cover, flow would go the opposite way. Incoming air rushing through air cleaner would create a Venturi and draw gasses from the crankcase into the intake. That would also cause some oil residue on the pcv filter inside the air cleaner. I bet it flows better than a road draft tube. Back to my first reply, crankcase IS vented, but trash can get in the valve cover.

 

before road draft and PCV systems engines were vented through the oil fill cap. There was no active scavenging of the crankcase. Every small engine out there has no active scavenging of the crankcase. Having the PCV missing out of the hole like above just means the crankcase is not actively scavenged, it is still vented. Actively scavenging the crankcase reduces moisture trapped in the engine this is especially the case for short trips. . Now considering the inlet for the PCV system in EFI engine is after the air filter the will be a pressure drop in that spot due to the air filter so it will be scavenging into the induction tract, or flowing in reverse.
The issue is the hole from the missing PCV will be sucking in air and any debris also.

 

All:

Your insights/opinions are all appreciated - which is why this forum is so great.
After reading your thoughts I have to think that the PCV has been out of the manifold for longer than I have owned the truck (going on 2 years) and that the three P.O.'s might have never noticed it either. Earlier this summer I had to get the seals on the valve covers replaced since oil was leaking from them so that could have been a result of this situation. Also, I have noticed since I have owned the truck that the engine oil gets very dirty very fast. I only drive the truck on the weekends and only have 500 miles or so on this oil change but the oil looks like it has been in there for 3K. So I only assume that inside the engine its a sludgy mess. Idea: Can I use Seafoam in the crankcase, run it for a short while, then drain the oil and put a new filter and high mileage oil in it? Short of tearing down the engine and cleaning it out - which I am not capable of doing with my very basic skill set, would this help or harm the engine and the sludge situation?

Update: I did buy a new PCV and installed it into the port. I drove the truck around the neighborhood and the PCV stayed put. All is well there. In fact, I did a Key On Engine Off code check (Yes, I am learning from you all and bought an OBD 1 reader.) and one of my Codes disappeared. Victory.

(I did have an engine flutter and stall though. That could be another issue. I will work on that but if I can't figure it out I may eventually ask for help.)

Anyway, thanks again for your help. It is much appreciated.