Hey all,
Been a while since I posted, been busy getting ready for our first baby that's due in December. And the XJ has been running good (knock on wood) for the past few months after a bunch of work I did last winter and spring. I just changed the oil and checked the air filter, was disappointed to find oil on the filter because last spring I replaced the CCV hoses with a new OEM kit, pulled the valve cover and cleaned it completely, and thought that it would flow properly - FROM the air box, THROUGH the valve cover, OUT into the intake manifold.
Dumb mistake.
Seems the laws of physics DO apply to a Renix 4.0, although the bean counters clearly thought they had a special pass when they eliminated a check valve in the PCV system and (incorrectly) assumed that valve cover air would only flow IN the big tube (airbox to valve cover) and OUT the little tube (valve cover to intake manifold).
Anyway, I came up with a fix, I think. Best part is, it's cheap and easy. Here's what I did, but a few words of caution first. Doing this mod without the following checks first could result in over-pressurization of the valve cover.
1) your CCV hoses need to be flowing air - if they are clogged or rotted, replace them first.
2) remove the fitting into the intake manifold and make sure it's not all clogged up with crud. You should be able to see the bottom of the intake manifold through the hole, if not take a pick and chip out the crud and then use a vacuum to suck it out. Pulling the throttle body will make cleaning the inside of the intake easier.
3) save the hoses you replaced in step (1) and cut them up, instead of your new one. That way you can switch back if this doesn't work for you.
4) if your valve cover gasket is leaking, replace it first. This mod might cause higher pressures in the valve cover that could make a leaky valve cover worse.
OK, here's what I did:
1. buy these 3 items (ignore the elbow, it's a piece of my old ccv hose I cut up)
That's 3/8" fuel line hose on the left. Can be vacuum hose too. Close-up of the p/n's of the other 2 parts:
2. remove the "cane" shaped hose off the intake, make a couple cuts, re-assemble like this:
The hose clamp is probably unecessary but I had it lying there so I figured I'd use it.
4. End result:
5. Check to make sure air is flowing properly by removing the hose at the air box with the jeep running, and at the intake manifold. Mine was blowing a lot harder out the small line to the intake manifold than it was before this mod, which tells me it probably achieves the desired results. In fact the small fitting out the valve cover whistles now (with the hose removed), which it didn't do before!
A final word, I just installed this today and have not run it for an extended period of time. If I find any problems I will post back up, but if you decide to do it I would recommend checking the valve cover gasket for leaks periodically to make sure you haven't created a problem.
Been a while since I posted, been busy getting ready for our first baby that's due in December. And the XJ has been running good (knock on wood) for the past few months after a bunch of work I did last winter and spring. I just changed the oil and checked the air filter, was disappointed to find oil on the filter because last spring I replaced the CCV hoses with a new OEM kit, pulled the valve cover and cleaned it completely, and thought that it would flow properly - FROM the air box, THROUGH the valve cover, OUT into the intake manifold.
Dumb mistake.
Seems the laws of physics DO apply to a Renix 4.0, although the bean counters clearly thought they had a special pass when they eliminated a check valve in the PCV system and (incorrectly) assumed that valve cover air would only flow IN the big tube (airbox to valve cover) and OUT the little tube (valve cover to intake manifold).
Anyway, I came up with a fix, I think. Best part is, it's cheap and easy. Here's what I did, but a few words of caution first. Doing this mod without the following checks first could result in over-pressurization of the valve cover.
1) your CCV hoses need to be flowing air - if they are clogged or rotted, replace them first.
2) remove the fitting into the intake manifold and make sure it's not all clogged up with crud. You should be able to see the bottom of the intake manifold through the hole, if not take a pick and chip out the crud and then use a vacuum to suck it out. Pulling the throttle body will make cleaning the inside of the intake easier.
3) save the hoses you replaced in step (1) and cut them up, instead of your new one. That way you can switch back if this doesn't work for you.
4) if your valve cover gasket is leaking, replace it first. This mod might cause higher pressures in the valve cover that could make a leaky valve cover worse.
OK, here's what I did:
1. buy these 3 items (ignore the elbow, it's a piece of my old ccv hose I cut up)
That's 3/8" fuel line hose on the left. Can be vacuum hose too. Close-up of the p/n's of the other 2 parts:
2. remove the "cane" shaped hose off the intake, make a couple cuts, re-assemble like this:
The hose clamp is probably unecessary but I had it lying there so I figured I'd use it.
4. End result:
5. Check to make sure air is flowing properly by removing the hose at the air box with the jeep running, and at the intake manifold. Mine was blowing a lot harder out the small line to the intake manifold than it was before this mod, which tells me it probably achieves the desired results. In fact the small fitting out the valve cover whistles now (with the hose removed), which it didn't do before!
A final word, I just installed this today and have not run it for an extended period of time. If I find any problems I will post back up, but if you decide to do it I would recommend checking the valve cover gasket for leaks periodically to make sure you haven't created a problem.
