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CCV confusion?

W

Wow

NAXJA Forum User
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Over there!
I'm trying to check out the CCV system on my '96 XJ, but I'm totally confused. I have a Haynes manual but it focuses on earlier models which have a different system than my '96.

Anyway - the hose that comes out the front of the valve cover - is that supposed to have vacuum or is it supposed to blow air? If so - how much? Mine seems clogged...there's a tiny bit of vacuum but it's barely detectable.

If it does happen to be clogged, do I need to care? I just passed an emissions test and it runs fine...
 
CCV Stands for CRANK, CASE, VENTILATION... Why on earth would a VENT be a source of vacuum? The idea is to expell gasses back into the intake instead of them be trapped inside the crank case. :wierd:
 
Why would it be a source of vacuum? Because the Haynes manual tells you to check for that. There are two parts to the CCV system, they don't both blow. I'm fully aware of what CCV stands for.
 
Yeah, it's definately a vacuum. I held a cigarette right in front of the hose and it sucked up all the smoke.

So my question is, SHOULD this front hose be under vacuum, and if so, how much?


My old '90 XJ blew smoke and oil out this hose, but the '96 has a different system.
 
Last edited:
dlarrivee said:
You're using a cigarette for engine diagnostics... I give up on you already.
Click to expand...
I for one certainly hope you don't add anymore worthless replies to this thread. You're outright WRONG first of all, and secondly, rude. So just go away and let someone who knows what they're talking about answer.... :rolleyes: :rolleyes:
 
hey your the one that uses a cigarette to test the vacuum. Nominated!
 
every one that I've seen (that functioned correctly)pulled air from the air box in the front and expelled crankcase vapor into the intake from the rear. It sounds as though yours is functioning correctly:yelclap:
--Shorty

P.S. you Jeep isn't 18 yrs old, so it shouldn't be smoking. You're contributing to the delinquency of a minor if you're giving it smokes!!
 
Shorty said:
every one that I've seen (that functioned correctly)pulled air from the air box
Click to expand...

Ok...is there any amount of air it should be sucking? I can barely detect a vacuum by hand, that's why I needed smoke to see it.


And, BTW - smoke is a very good and very well known tool for watching airflow. If anyone thinks there is anything wrong with that then they're an idiot. I'm smart and resourceful for using what's at hand.
 
You're a fawking jack ass is what you are Wow, get off your high horse and stop acting like your smarter than everybody else.

No, the CCV system will never have a huge amount of draw, if you can blow through it than it's good, if you're picking uip a lot of oil in your airbox then you'll know it's blocked and you'll have to pull the valve cover in order to clean the system out.
 
Gee, you've gotten so much help so far!

If the 96 is like the previous years, there is a vacumn line to the rear of the valve cover with a metered hole in it. That's supposed to draw the crankcase fumes into the intake. Check that the line is clear by flushing it with carb cleaner. The bigger line out the front of the valve cover is to let fresh air into the engine.

If you're getting air blowing out the front, either the rear line is plugged or you've got a lot of blowby.
 
Yeah, that's right, I'm a jackass for asking a simple question and getting worthless replies from idiots. :rolleyes:

The only one who bothered to help in this thread is Shorty, and I thank him for that.
edit: lawsoncl, too.
 
dlarrivee said:
You're using a cigarette for engine diagnostics... I give up on you already.
Click to expand...

:laugh: :laugh: :laugh: :laugh: :laugh: :laugh:
 
Aren't we picky tonight! FWIW I don't see any jackassian behavior on your part and I see nothing wrong with using smoke to track air currents. It would appear that one of your critics doesn't understand that the intake manifold is the vacuum source for the CCV system.

What I really wanted to add is that while there may be good reason to pull the valve cover for other concerns, it is may not be necessary for this purpose. On my '93 I was getting a bit of oil in the air filter and eliminated it completely by cleaning the rear vacuum line, and in particular, the fitting that screws into the manifold. That fitting was partially blocked with carbon deposits and is easy to pull and clean.
 
A fresh air supply hose from the air cleaner is connected to the front of cylinder head cover on 4.0L engines. It is connected to the rear of cover on 2.5L engines.

When the engine is operating, fresh air enters the engine and mixes with crankcase vapors. Manifold vacuum draws the vapor/air mixture through the fixed orfice and into the intake manifold. The vapors are then consumed during combustion.
Click to expand...

That's from my FSM for an '01 XJ.

I may have been confused earlier, as I thought you were pulling the tube from the valve cover and hoping to feel vacuum at the valve cover, when the vacuum source is actually the intake manifold... Sorry for the rude comments.
 
Oh Ma Gawd!!!

Would you all just shut the fuck up!!

Smoke has been used for years in helping diganose engine and other problems. When I was in auto tech classes, we used a smoke generator to help find water leak around door jambs (only becouse of the no smoking rule in the shop).

Turn the fan on high, close the door and then use the smoke machine to find the spot where the water is coming in. The smoke will be disturbed where the door jamb is leaking.

The same thing can be done to find Vacuum leaks (as well as the vacuum for CCV line).

To clean your CCV line, run some carb cleaner through it with the engine running. That should draw it down the line into the manifold.

BTW, You only want vacuum at the smaller rear line. The big front line that goes to the air box shoould have very slight vacuum. If it blows at you, it's time clean or replace the smaller line at the rear.....
 
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