Air intake/filter Questions

[Henry89Manche]

Ok so first question! If your looking down on air filter box, there is a hose bottom left that runs up and under exhaust manifold! What is the purpose of the hose?

2nd question! There's oil getting built up on the top of my air filter, coming out of one the vacuum lines coming from valve cover! What could be causing that, and would it be possible to run a small breather tank with drain C#*@ at bottom to rid of that issue? And 3rd if I were to run a cold air intake, what would have to be done with the vacuum lines, if someone who already did this, have pictures?

[75sv1]

Hose is the heater hose. It lets hot/warm air heated from the exhaust to warm up air on cold days for emissions.  The oil in the air filter is usually referred to as "blow-by'.  It isn't technically 'blow-by', as in combustion getting by the piston rings. I have found it can be a poor seal of the valve cover gasket. I 'upgraded' to an HO valve cover. I'd also look at Cruiser's Tips. A member here. He'll probably chime in. Another solution is to do away with the lines from the front of the valve cover to the airbox.  Then install one of the "hot Rod' style valve cover breathers.  You could do this also if you go to a 'Cold Air' intake. Not sure if the add much HP or just lighten your wallet.

            Also, as to the 'Blow-By' you can 'update' to the bigger rear breather tube. Late XJs 2000-2001. I did have a '95 valve cover on mine. The '93-96 Grand Cherokee had the newer grommet CCV system. I have two of them and plan to install one on my XJ and the other on the MJ. Also, there is an upgraded valve cover seal from FELPRO. It about $40, though. I bought mine at NAPA. Its a rubber or silicone gasket.

[88mjblue]

I see this is your first post, and that you have an 89. Here's some required reading for you: cruiser54.com

Tip #25 is for the oil issue you're talking about. Lots of other good stuff there.

Also read up on Renix (87-90) vs HO (high output) (91-92)

Welcome!

[ParadiseMJ]

The hose...or tube...is, as said above to send warm air from the manifold when the servo is opened by the bi-metal valve in the rear of the box. It's called a "thermostatic air cleaner" Two little vacuum lines lead to and away from the sensor and it  senses when the engine, or the airflow is warmed up and shuts the servo.  I recently took off my cone filter (aftermarket) that "said" it was 50 state legal (for a Cherokee), and it is according to The Smog Man.  But it's on a Comanche, so he disqualified it, even though it's the same damn exact Renix engine. I took it to a "Gold Star" smog station and they confirmed that.

 

So, if you live in California that hose is supposed to be on there.  Otherwise, it's up in the air as to whether your state allows an aftermarket set-up.  But even so, when I took the cone off and re-installed stock airbox and all the vacuum lines, it feels like the truck runs better, is quieter and it's legal.  Pain in the rear, but that's my experience.

[Henry89Manche]

Thank you to everyone who replied! I really appreciate the help!