pcv valve for '96 4.0 ??

my 96 4.0 has the pcv (or ccv, whichever) elbow on the top of the valve cover, toward the front. A hose goes from it to the stock airbox tube.
So, I'm putting in new plugs, etc... tuning it up. I figure I'll replace that pcv valve, too. I'm looking in the filter book at Autozone, they show n/a for the 96 4.0. Am I not looking at the right thing, or what.
Also, I'm going to make a custom cone air filter tube for it, and was wondering if I need to run the hose from this elbow to the new air tube, or can I just put one of those miniature cone air filter looking things in the elbow's place?

You probably don't have a PCV valve.

The early (and later?) AMC242 uses a CCV system - Constant Crankcase Ventilation. This means that there actually is NO pcv valve, and you might have to clean or replace the hoses instead. I know that there are aftermarket solutions available for RENIX (1987-1990,) and there might be for HO (1991-up) as well - check with NAPA, through their Echlin catalogue (house brand.)

Failing that, you can go to the dealership.

The PCV valve was frequently deleted with later fuel injection. Since "backfiring through the carburettor" ceased to be a problem with a well-running fuel injection setup, the PCV valve wasn't needed anymore. The original intent behind the PCV valve was to allow gasses to escape the crankcase (fuel-laden blowby, mainly,) and have a means to cease flow if/when the engine backfired through the carburettor. Backfiring through the carburettor with an open PCV line would mean that ALL that fuel would be ignited, and the engine possibly wrecked.

I think you'll find that most late-model vehicles do not have PCV valves anymore, although they were still common on early fuel injection setups - especially TBI.

5-90

the earlier xj's were the only ones to use a pcv.The later models use the ccv system you mentioned in your post.It's basically the same concept.

Whatever you do when you add the air tube,put some kind of filter on the ccv inlet....if not it would be like running with no intake filter.

Unless you're referring to the GM2.8LV6 or the AMC151CII4, the RENIX 4.0 didn't use a PCV valve either. Of course, I've not seen a 1984-1986XJ under the hood, so I'm hardly an expert - but there are no PCV valves on any of my XJ's... 1987/4.0, 1988/4.0, 1989/4.0, 1989/4.0

Just checking your data...

5-90

ok, so, what's that little elbow with the hose running from the valve cover to the air box tube?

it's the crankcase vent.
You have a ventilation system, but there is no vavle. If you're having problems with blowby then try cleaning the valve cover.
http://www.off-road.com/jeep/cherokee/98/04_apr/valvecover/cover.html
If that doesn't work then the lines might be plugged.
How the system works is pretty simple.
Vacuum from the intake manifold pulls air from the back of the motor. This pulls FILTERED air from the air box from the front.
If the rear line becomes clogged then the system reverses itself. Now you've got a greater vacuum at the air box, and the CCV line will drench the air filter with oil.

Yep - so what you've got is a "constant" flow of fresh air into the crankcase, and flushing the fuel-laden blowby gasses out and back into the intake stream.

Most CCW failures are directly traceable to crap buildup in the system, and just wnat a cleaning. In extreme cases, there's a broken vacuum line (since they're Nylon, and get brittle.)

Take your vacuum harness off, flush it with some carburettor cleaner, and run a bit of SOFT wire through the lines to push everything else out (oddly enough, I've found picture wire to be most useful for this - it's stiff enough to push, but not so stiff that it will push right out the side of the line.)

Clean the baffles in the upper valve cover as well - take it off to do this.

You should find that helpful with the issues you're having. Let us know if you still have trouble!

5-90

get the plastic elbows and the rubber grommets from the dealer, along with the tubing that goes from the rear of the valve cover to the intake manifold.

the front tubing/rubber connectors can be replaced with generic tubing/hoses.

the two elbows and two grommets cost me 10-15 dollars at the dealer.

I used part numbers for a 2000 on a 97, but they should fit on the 96 as well.

(the '00 rubber grommets are thicker than the old ones I took off, and seem like they seal better.)

HTH

B

The CCV is actually in the rear tube. It is a metered port. Take a paper clip or a small drill and clean it out. Also, the valve cover seal needs not to leak. The 96 should have the newer rubber valve cover seal. I haven't heard any problems with them. YOu might look at the MAD-XJ site for info to update to the newer larger diameter CCV tube (99+).
Tom