Vacuum both PVC's to intake?

[Triman]

Ok, I've searched to death on this with no luck, and at wits end here.

I've got two PCV holes in my valve cover, one (front) is vacuumed by the carb and going to intake. the other (rear) SHOULD be going to air filter to take in air....

BUT, when I pull the (rear) hose from the air cleaner when the engine is running, there is air coming out of it, rather than pulling in...

Should this be happening? If I pull the hose from the carb that is pulling from the front pcv hole, the engine stalls.

Should I vacuum both holes with carb to intake to pull the pressure?

Not sure this is normal....well, based on searches, I know it's not normal... Any help?

 

[IOPort51]

have you replaced or cleaned the PCV lately??

Ok, I've searched to death on this with no luck, and at wits end here.

I've got two PCV holes in my valve cover, one (front) is vacuumed by the carb and going to intake. the other (rear) SHOULD be going to air filter to take in air....

BUT, when I pull the (rear) hose from the air cleaner when the engine is running, there is air coming out of it, rather than pulling in...

Should this be happening? If I pull the hose from the carb that is pulling from the front pcv hole, the engine stalls.

Should I vacuum both holes with carb to intake to pull the pressure?

Not sure this is normal....well, based on searches, I know it's not normal... Any help?

 

[Torxhead]

Sounds like you have it set up correctly, They do require cleaning or replacement, along with the crankcase vent filter.

 

[Triman]

have you replaced or cleaned the PCV lately??

The PCV that I am using now is brand new...rattles when I shake it.

Will I have "mass failure" if I vacuum both openings?

Thanks for all the help.....just at my wits end and running out of searches on the 'net.

 

[Torxhead]

I'm not sure what would be gained by that, most guys try to eliminate the pcv system entirely to stop all that blow-by from going down into the engine. I have seen guys stuff a breather cap in the rear hole also. I have mine set up the way it came to pass emmissions testing.

 

[Triman]

So I had a T and some extra hose from replacing the hose to the tank. Both PCV holes are being suctioned and it seems to idle higher. But nothing else. Let it idle for a while and temp was ok, oil ok, no funny sounds that I could hear...

Might drive it around a small loop in the neighborhood to see what it does...will update from the side of the road if needed.

 

[IOPort51]

OK guys , a couple of questions: How did you determine that the hose that went to the breather was blowing air and not sucking it?? I just put a manometer on mine this afternoon and it most definitely draws air, not a lot but it does. If you put a vacuum on both ends I would think that the crankcase will draw the air from some place, dip stick tube, valve cover gasket, rear main seal? Put a 5 or 6' length of clear plastic hose on your breather end at the valve cover and put the other end of the clear hose in a glass of water on the ground. Does it blow bubbles or draw water up the hose? I say 6' hose and glass on the ground to give you time to pull the hose before it sucks water into the valve cover.


question #2: I had not seen anybody blocking off the PCV, Why would they do that?? I could understand removing the TAC and the control for the pulse air system, if you could not figure out how they work. but blocking the PCV would improve nothing that I can think of.

Please enlighten me!

 

[mtnwhlr]

You need a pcv valve. It should go in the front of the valve cover. If you have one in the rear it should not be there that is for your vent. I'm not sure where the hose goes from it off the top of my head but I will look at mine tomorrow in the light and let you know.

 

[Triman]

OK guys , a couple of questions: How did you determine that the hose that went to the breather was blowing air and not sucking it?? I just put a manometer on mine this afternoon and it most definitely draws air, not a lot but it does. If you put a vacuum on both ends I would think that the crankcase will draw the air from some place, dip stick tube, valve cover gasket, rear main seal? Put a 5 or 6' length of clear plastic hose on your breather end at the valve cover and put the other end of the clear hose in a glass of water on the ground. Does it blow bubbles or draw water up the hose? I say 6' hose and glass on the ground to give you time to pull the hose before it sucks water into the valve cover.


question #2: I had not seen anybody blocking off the PCV, Why would they do that?? I could understand removing the TAC and the control for the pulse air system, if you could not figure out how they work. but blocking the PCV would improve nothing that I can think of.

Please enlighten me!

I can answer #1 last week when going though the web and verifying that I got the pcv system right, I pulled the front pcv from the carb(suction) and the motor died. Replaced hose and pulled the back pcv hose from the air cleaner and I could see air coming out. Saw it due to the color, it was like fog coming out, kinda slow. When I rev'd the engine, I thought it would suck in air, but it blew more "fog" at a higher rate. Can try to do it again tomorrow, but pics with the iPhone might not show the color of the smoke coming out. Maybe a video on utube.

As for #2, I would think that would cause some serious blow back if there were no ways to relieve engine pressure. My 2 cents. But here I am asking for help.

Results from tonight with vacuum on both, it tends to idle higher, but that is it. Pressure is good, temp is good, drove to the store and had no issues, just a higher idle.

By the way, not sure if it matters, but getting 10 mpg on a good day with the jeep. Normal? I figured the AMC 258 i6 / 4.2l would almost be in the near 20's. Am I dreaming this stuff up?

 

[IOPort51]

I would have to think you need some rings. Have you done a compression test ??

Is the PCV connected to the back port of the carb or direct to the intake manifold??

 

[Triman]

Rings. (sounds bad, more google'ing in my future)

No compression test yet. Will search how to do tonight also and try in the am.
The "vacuum" that I keep referring to is on the back of my Holley carb. The source of that looks like it goes down the middle of the carb and connects to the intake manifold via a hose from the bottom of the carb. I'll take some photos in the am.

So if it is rings, how long do I have? Was planning to drive it this summer, and rebuild the motor when it gets cold, granted, that won't really be till October here in Alabama.

 

[IOPort51]

Pictures would be good. If you could finish your profile with things like engine size, Transmission , Transfer Case , axles, ratios, girlfriends photo and phone number.

Rings. (sounds bad, more google'ing in my future)

No compression test yet. Will search how to do tonight also and try in the am.
The "vacuum" that I keep referring to is on the back of my Holley carb. The source of that looks like it goes down the middle of the carb and connects to the intake manifold via a hose from the bottom of the carb. I'll take some photos in the am.

So if it is rings, how long do I have? Was planning to drive it this summer, and rebuild the motor when it gets cold, granted, that won't really be till October here in Alabama.

 

[IOPort51]

The second question was for Torxhead more than you. We agree on this point.

you did the same thing in the title that I do about 1/2 the time.

Polyvinyl Chloride/ positive crank cast ventilation

 

[Triman]

The second question was for Torxhead more than you. We agree on this point.

you did the same thing in the title that I do about 1/2 the time.

Polyvinyl Chloride/ positive crank cast ventilation

Damn autocorrect on these computers. It has been officially been added to the computer dictionary. At least...that's what I'm claiming.

Granted, 90% of all failed searches is tied to bad spelling. I might ask CJ to fix it.

 

[IOPort51]

I'm gonna have to remember that one , it almost sounds believable.

Damn autocorrect on these computers. It has been officially been added to the computer dictionary. At least...that's what I'm claiming.

Granted, 90% of all failed searches is tied to bad spelling. I might ask CJ to fix it.

 

[mtnwhlr]

So you should have a PVC in the front of the valve cover with a hose that runs to the base of the carb. In the back of the valve cover you should have a elbow with a hose that goes to the aircleaner. That is if you have a AMC 258 i6 / 4.2l

 

[Triman]

So you should have a PVC in the front of the valve cover with a hose that runs to the base of the carb. In the back of the valve cover you should have a elbow with a hose that goes to the aircleaner. That is if you have a AMC 258 i6 / 4.2l

Well, thats how I had it setup. But when I pulled the rear hose and saw smoke coming out of the back pcv rather than it sucking in. So that's the reason for me starting this thread. Trying to find a compression tester nearby that I can pick up and try what IO recommended.

 

[bondo258]

Either hole in valve cover can have the PCV in it, and the "breather" hose in the other.

Factory setup was PCV in front for AMC 258 i6 / 4.2l .

"Oil Fog" blowing from the valve cover while running is a definite sign of worn ( or possibly misaligned) Piston rings, Either one means pulling the motor for a rebuild/ and cylinder rehone. Worn valve guides would be causing a lot more problems than you seem to be reporting.

Lots of ways to deal with this until rebuild time. None of these qualify as "repairs". A repair for worn piston rings, is replacing the rings, and honing the cylinders. Period.

Plenty of disclamers here:

A)

Push in breather in place of air cleaner (not PCV valve) hose. Cap the port if yours was connected to the Carb, as you said it was.

Downside, you get a light trickle of oil down to the the rear and possibly sides of the valve cover. This isn't a leak. It's condensed oil, that may find its way to your exhaust manifold.

A finned Aluminum cover won't generally allow this. It will stink a bit, and if it gets worse, it may present a fire hazard. I've seen it smoke, when my motor was tired and set up like this, but it's equally hazardous to a valve cover oil leak. use your own judgement, Not sure of the flashpoint of motor oil, but it seems higher than normal underhood temps.

If you don't already carry a fire extinguisher, here's another good reason to.

B)

Run TWO PCV valves into one another, and tee'd into a "catch can".

Basically a metal canister, secured out of harms way, with an inlet in the side or top, a drain valve, or petcock in the bottom, and a breather outlet in the top. This goes to your PCV port on the Carb.

The idea is to condense the vapor inside the can, and you get a condensation of "goo" in the can. Don't pour this into your motor after it becomes full.

Dispose of properly in accordance with whatever rules apply.


C)

Run two PCV's into a Tee. Run the Tee to the low port on your carb, as it was.

You plan on running it all summer, just prepare to change/clean your spark plugs regularly. Keep a set of fresh ones and the tools to change them, just in case.

You will need to clean extra carbon out of your head, and manifolds, at rebuild time, if you go this route,This is a major drawback of doing this. It also acts like an mini - EGR system, depending on how bad the "blow-by" is. Much harder to tune.

If you have a functioning EGR system, it may get clogged by doing this as well. A check of this every time you pull your spark plugs is a good idea.


Don't plug the grommets, you'll blow a crank seal, oil pan gasket, or valve cover gasket, immediately. If you are lucky, it will pop the push in style oil fill cap like a champagne bottle.


Summertime stinks running a sub-par CJ. If not your daily driver, any of the above should carry you through the Summer. Running heavier oil may help slightly, as well.

Provided your compression numbers are up to snuff. If they are not, park it and fix it early, and correctly.

 

[jasonmark1993]

Bondo gave you some good info.

Make sure that the pcv valve is hooked to a vacuum source below the throttle plate. You'll know it is if you have vacuum there at idle.

Was this hooked up when you pulled the breather tube off?

So you're engine is a little worn out. I wouldn't stress about it too much.

Either run a breather and vent that stuff to atmosphere or continue to run it through the air cleaner.

 

[Triman]

Thanks for all the advise.

With two little girls in the house (11m and 3y) I'm Limited on the engine work till the weekends but I was able to get the spark plugs out tonight to prepare for the test. Note that I put these plugs into the jeep about a month ago. See below for results.

More detail on the engine is that it has 63k on the odometer. I've had it about 2 months now and put several hundred on it since. I've been putting 30w oil in it to keep it from leaking, however, I bought a 5w20 by mistake a few weeks back and thinking that is the reason for the oil in exhaust and dirty spark plugs, but please correct the rookie if he is wrong. I'm learning here

I'll try the compression tonight while I'm in the driveway, then put the spark plugs back in to get it in the garage. Figure I can clean the spark plugs some prior to putting them back in as well. Will post compression numbers later tonight.