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Valve cover vent hole?

afd516

afd516

NAXJA Forum User
Location
Fort Worth, Tx
I tried to look at pics of engines on here but it is hard to tell what years and modifications may have been done to the engine I looked at to tell what I need.

The vent hole at the rear of the valve cover is missing whatever plugs in there and I don,t know where it goes to. I imagine it goes to the air box.

Btw I have an 89 xj with a 4.0. Does any one have a pic or any info to help me out? Can I just plug up the hole in the valve cover? :dunno:
 
It should be where thr CCV hos plugs in. There is a picture of it in the Chilton book for your rig on page 1-16. If you need a new hose it is available from NAPA (part #715365 $7.99)
 
treedoc thanks for the pic it answers alot but it is hard to tell where the hose ends. Can you help me to tell that?

mrbill3 thanks for the part # i will check it out tommorow.

:cheers: to both of you.
 
Hope you dont mind if I tack onto your thread afd, But I have a 93 cherokee with the same problem of oil in the air filter. Is this the same probelm even though it says that it only effects 87 through 90 xj's?
 
on your intake manifold there are four vaccum ports, three on the windshield side of the throttle body, one on the grille side. this grommet will connect, via a small plastic line, to closest to the throttle body, windshield side.

the chilton's mrbill recommended will become your new best friend.

pogiboy, you are experiencing a very common problem with many years of the 4.0. search "oil on air filter", and/or hit the link in my answer.
 
treedoc said:
on your intake manifold there are four vaccum ports, three on the windshield side of the throttle body, one on the grille side. this grommet will connect, via a small plastic line, to closest to the throttle body, windshield side.

Thank a million that is exactly the info I needed. :worship:
Click to expand...
 
Look at http://www.madxj.com/ . THey have an article on the CCV upgrade. The rear tube goes to a brass fitting on the intake manifold on both the Renix and the HO. The HO is towards the rear of the engine of the throttle body and on the Renix it is in front of the throttle body. I might have a picture of the Renix setup somewhere is you send me your e-mail. If you getting oil in your airfilter, you need to get the CCV hose hooked up. If it continues, then take of your valve cover. Clean out any crude in there and get a good seal on the valve cover. I'd use RTV. I did put a '95 valve cover on the Renix Motor. It worked good.
Tom
 
My motor is freshly rebuilt, less than 1500 miles on it, It did not have anything going to the valve cover and the vacume tree on the intake is pluged up.

This is why I questioned what this was. It apperantly is some kind of emmisions crap, I am guessing.

If I have the other hole at the front of the valve cover going to the airbox this would relieve crankcase pressure, correct?

And, if I do not care about emissions for a trail rig only xj can I just plug the hole at the back of the valve cover and keep the plug in the intake? :confused1

mrbill3 I found that part# but if I can go without it?
 
afd516 said:
My motor is freshly rebuilt, less than 1500 miles on it, It did not have anything going to the valve cover and the vacume tree on the intake is pluged up.

This is why I questioned what this was. It apperantly is some kind of emmisions crap, I am guessing.

If I have the other hole at the front of the valve cover going to the airbox this would relieve crankcase pressure, correct?

And, if I do not care about emissions for a trail rig only xj can I just plug the hole at the back of the valve cover and keep the plug in the intake? :confused1

mrbill3 I found that part# but if I can go without it?
Click to expand...
You need one for air into the crankcase and one to suck air and water vapor out.
Before PCV valves there were still two. The filler cap had a vent and air filter built in and there was a second pipe that went down under the car to pull the fumes and water vapor out of your crank case.
Now days fresh air goes in through the air box and is drawn out by the PCV valve.
 
The gas and vapor from the rear one goes into the intake manifold. It gets mixed into the intake air and fuel mixture and gets burned in the combustion process. The rear tube is a metered port, that does the job of the older PVC valves. I don't think that tube or gromment cost very much from the Jeep Dealership. Probably around $10. It is emmission related. Before the PVC valves, the gasses would be vented out into the air.
Tom
 
afd516 said:
Sooo, from the hole at the rear of the valve cover the vapor and water comes out and goes into the intake and out the exaust?
Click to expand...
Correct Automotive crankcases have always been Positive vented, the only change is how it is done.
 
You learn something new everyday!! I will try to come up with the part that I need.

THANKS very much for the info. It expains alot.

I may have more questions so be prepared!!! LOL :)
 
Everyone stay calm and no one will get hurt...I'm hijacking this thread and taking it to Brazil....

1989 4.0, manual

In the event that my PCV valve IS not working, then I must replace the entiresvalve cover? Cuz when I pull that hose out (the one on to of the valvecover, nearest the firewall) I don't feel any vacuum. There's no oil on the airfilter though...
 
on mine the line and valve were both plugged, but intact. seemed pressed in, didn't come out with various prodding. cleaned it with seafoam, fine wire, and bit of biocompressed air.
 
Last edited:
Biernuts said:
Everyone stay calm and no one will get hurt...I'm hijacking this thread and taking it to Brazil....

1989 4.0, manual

In the event that my PCV valve IS not working, then I must replace the entiresvalve cover? Cuz when I pull that hose out (the one on to of the valvecover, nearest the firewall) I don't feel any vacuum. There's no oil on the airfilter though...
Click to expand...
You just get a new PCV valve and make sure the hose is clean.
 
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