PCV blockage in intake manifold?

[ZGjethro]

I am trying to see if mytruck's PCV system is functioning properly since I have had some buttery emulsification on the underside of my oil filler cap. I pulled the PCV valve and the shutoff valve assembly off of the truck and air easily blows through it and the piece in the PCV valve freely moves. I put a piece of fuel line on the pipe stub coming out of the intake manifold above the heat riser, and I could not get any air to flow when I blew or sucked on the hose. A match stick inserted into the pipe goes in about 1.5" and stops. I was wondering if there is an elbow passage or reduction in the diameter of the orifice which could easily get plugged? I also got no vacuum at that same pipe when the truck was running. The tube coming out of the block seems free of obstruction. When I get a little time I will pull the carb and take a look, but I was hoping to get a little information in the meantime.

[ZGjethro]

So I pulled the carb and decided the PCV circuit is plugged in that pipe at the manifold. Any advice on how to pull the pipe? Double nut trick?

I also had a little pool of gas in the bottom of the manifold. What would keep that from flowing back down the PCV circuit into my crankcase? Would the PCV valve stop liquid gasoline? When I first got the truck the oil smelled strongly of gasoline and it was running really rich

The PCV valve has a little piece in it which rattles around and plugs an orifice. Is that all there is to that valve, a weighted valve not unlike the valve on a pressure cooker?

[pwrwagonfire]

According to the manual, this set up is supposed to be serviced every 6,000 miles. I just checked mine out, and it was plugged SOLID...I'd suggest taking the whole assembly off and soaking it in seafoam or something like it to clean it out...one of those wire pipe cleaners helped me.

I got the pipe nipple (part which connects to the intake) out by using very moderate heat, and clamping down with a set of vice grips and it turned right out. I was dreading it, but it actually was no issue at all.

Let me know how it goes!

-T

[ZGjethro]

I have the whole thing soaking in gasoline now to soften the accumulated grime on the outside. As soon as it can get that stuff off I will take all the parts apart and really clean them.

I was hoping to avoid vice grips, but that might be the tool to use if the double nut does not work. I am sure I will mar the pipe. I am going to take the nut to the hardware store and try to find another one tomorrow. Too bad they didn't put a hex flange on the pipe.

Any opinions on the fuel in the bottom of the manifold? I had M-series rebuild do the carb rebuild and Pertronix ignition in 2010 and that got the truck running a lot better. Still, it is rich. I had idled the truck for about 10 minutes, and never really revved it before I pulled the carb, so that could account for some fuel remaining. And what would prevent that gas from flowing into the crankcase? The PCV valve does not seem fluid tight. I can blow through it with either end up.

Why would the designers of the intake put the PCV pipe pretty much flush with the bottom of the manifold where any excess gasoline would pool? If the oil has any strong gasoline odor, or is thin at the next oil change, I might route the pipe into my straight pipe intake which has a K&N airfilter on it. Does any one see a problem with the PCV circuit being before the carb?
Edit; I did a little reading. Oily vapor from the case probably is a bad thing to run through the carb. I would not mind a higher point in the intake manifold as a point to connect to though

[pwrwagonfire]

I have the whole thing soaking in gasoline now to soften the accumulated grime on the outside. As soon as it can get that stuff off I will take all the parts apart and really clean them.

I was hoping to avoid vice grips, but that might be the tool to use if the double nut does not work. I am sure I will mar the pipe. I am going to take the nut to the hardware store and try to find another one tomorrow. Too bad they didn't put a hex flange on the pipe.

Any opinions on the fuel in the bottom of the manifold? I had M-series rebuild do the carb rebuild and Pertronix ignition in 2010 and that got the truck running a lot better. Still, it is rich. I had idled the truck for about 10 minutes, and never really revved it before I pulled the carb, so that could account for some fuel remaining. And what would prevent that gas from flowing into the crankcase? The PCV valve does not seem fluid tight. I can blow through it with either end up.

Why would the designers of the intake put the PCV pipe pretty much flush with the bottom of the manifold where any excess gasoline would pool? If the oil has any strong gasoline odor, or is thin at the next oil change, I might route the pipe into my straight pipe intake which has a K&N airfilter on it. Does any one see a problem with the PCV circuit being before the carb?
Edit; I did a little reading. Oily vapor from the case probably is a bad thing to run through the carb. I would not mind a higher point in the intake manifold as a point to connect to though

The vice grips will without question bung up the threads, this part seems to be specifically soft...not brass, but it acts like it! If you have the operation and organizational maintenance manual, page 162 talks about the crank case vent system at length

-T

[Brett]

You could get a set of internal pipe wrenches. They insert in the pipe, and engage with a serrated cam when you turn it. Search them on amazon, they're not that expensive.

Brett

[ZGjethro]

Thanks all. The double nut method spun it right out. That 2" piece of pipe had three different threads and two diameters! My next issue is to determine why I had gas in the intake manifold. My Holley pressure regulator (electric pump back at the tank) has a gauge on it and it is pretty constant at 3psi, which might even be a little low. I will need to check my float level.

The idea of liquid gas flowing from the intake manifold to the crank case from a flooded situation got me thinking of plumbing a higher loop (about and inch) into the PCV circuit between the intake manifold hole and the PCV valve. Is there any negative to this? I cannot think of one. Any positive pressure from the crank case should flow as originally intended, yet gasoline could not flow over the loop. Would I need to keep the 1/4" diameter of the pipe stub for any vacuum/vent reasons?

[RMS]

I would rather have pooled gas run down the PVC than down the valve guides

[Kaegi]

I wouldnt worry about where the PCV is but rather be concerned that your flooding. float level too high? compressioin low? carb have internal leaks? should not be any fuel in bottom of intake

[ZGjethro]

Thanks for pointing out the possibility of gas running down the valve guides. I had not thought of that. I will be addressing the gas issue next. I think I will leave the factory plumbing alone for the meantime. Have any vehicles installed a collection jar for liquids on the PCV circuit?

[ZGjethro]

I was putting the carb back on, and noticed it kind of rocked when I put it on. It turns out the small casting by the idle adjustment screw was hitting the top of the stud on the passengers side of the manifold, keeping the carb from seating on the manifold. I ground off about a 1/16" of it and the carb sits solidly on the gasket now. I did not even know I had an air leak there! I only took a quick lap around the neighborhood, but it seemed like it hesitated when I stepped on the gas, and I had to downshift to second on a hill I always make in third gear. I am going to drive it a bit more and get a better idea of what it is doing. It seems like an air gap there would effect the pump circuit, as well as my fuel mixture, which I felt was rich before