Cleaning the CCV inlet without taking off the valve cover?

As part of my maint on my 91 and its 2.5, every once and a while I pop the elbow off and run a piece of music wire thru the brass orifice's hole to make sure its clear. DO NOT make the hole bigger using a drill bit or?? inside the VC behind the orface is a fairly large space with a baffle that likely would not plug up anytime soon.

Heather93yj said:

Thank you for your response. I should have clarified this is a 4.2 and has both the CCV and PCV. The CCV on the front of the inline 6 is the one that is gunkified. It's pretty thick and high up to the underside of the top of the valve cover. I was wondering if I could spray something in there.

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You’re referring to a Jeep other than the 93 in your profile, correct?

Heather93yj said:

No, just an airhead sometimes. It is a 4.0 I realized I had written 4.2 many hours later and was going to change it but this is the first chance I've had to sit and fix my error. I did so much reading yesterday after pulling that CCV off of there, and YouTube videos about it before I inquired but every one of them either takes the cover off, or just cleans the valves. That's why I was wondering if I could spray carburator cleaner in there. Again, thank you for your quick response and willingness to help despite my snafu. I do a lot of work on my Jeep, but I am limited to the lighter stuff due to lack of efficient tools and space/time for big projects.

PS, your Jeep is beautiful.

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Okay, wanted to make sure because it makes a big difference between 4.2 and 4.0. There is no PCV on the 4.0, it's all CCV. There are 2 CCV elbows, one of them has an orifice and one of them is free flowing. The front elbow should be free flowing, and the rear should have the orifice. With it being a 93 it could be the type of elbow that twist locks into the valve cover. On my 94, I just have circular grommets and the circular base of the elbows pops into the grommet and stays there.

If your post is about cleaning the "tower" going from the top of the valve cover down to the cylinder head (built into the valve cover), then that will be difficult to clean...

Basically the design is that the intake manifold pulls a vacuum through the valve cover to burn any unburned vapors floating around. The way to do that is to pull additional fresh air through the air filter, and then pull that fresh air through the valve cover so that air movement can happen through the intake manifold and into the combustion chamber. The rear elbow has the orifice so that the intake manifold doesn't get a massive vacuum leak through that elbow and run the rpm to redline. If you were to install a free flowing elbow in the rear location, your engine would go up to redline or close to it.

Also, thank you!

My valve cover looked like someone baked brownies in it. The towers came off by removing two screws and gave easy access to the brass fitting which was totally hidden with junk.

If you go that route be sure to use loc-tite on the screws.

Luckily for the 4.0, there is no brass tube. The elbow with the orifice acts as that component.

As for the towers, I don’t recall them being removable on my 4.0 valve cover but maybe they were and I just don’t remember. It’s been a long time.

Heather93yj said:

I do have a free flowing one on front and one at rear has the clicking sound when I shake it, obviously the mechanism inside. It needs to be cleaned, but is still "functioning". It's the one up front that looks like cooked brownies (! perfect !). So, no on the spraying anything in there and using like a bottle brush or something, eh? Ok. I don't know what is meant by tower. But, yes, I do have the turn click kind of CCV 's. Thankfully.

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Somebody put in the wrong part for the rear one - it should be a CCV with an orifice. Literally a free flowing elbow but with the orifice it has a tiny hole that lets through a specific amount of air. The 4.0 does not have a PCV valve or PCV system at all.

The one up front is probably all nasty because you have a PCV elbow at the rear that should not be a PCV.

By "towers", I am referring to pieces on the underside of the valve cover directly beneath the elbows holes. They are tubes that reach down close to the surface of the cylinder head so that oil is not flung up from the rockers onto the bottoms of the elbows. I'll post a pic below.

For the record, I don't like the twist lock elbows, I prefer the ones I have as you can find them at pretty much any parts store easily. Sometimes you can find the twist ones but not always.

I think you need to change your rear elbow to the correct CCV with orifice elbow and ditch whatever PCV part is in there.

Here is an example of the valve cover - you can see the two "towers", one by the oil fil cap and one by the rear of the valve cover. turns out they are removable as @Flyer58 said. I didn't recall mine being that way but like I said it's been a while. Those are what need to be cleaned out most likely, and you need to get the correct elbows installed.

You will still need to remove the valve cover to clean up any of this. If you try to clean from above, you're just going to push the gunk down onto the top of the cylinder head, which could get that stuff into the oil, valve springs, etc which you don't want. I'd just find some time soon and pull the valve cover. I can remove mine in about 30 minutes, so it's not that big of a deal.

You need this for the rear:


And this for the front:


Disregard the fact that Crown calls them PCV, they are NOT PCV, but they are the correct parts.

If you continue to have problems after cleaning the towers, and replacing the elbows, you probably have significant blow-by in your engine from worn rings or similar.

Don't just spray brake cleaner in there. All you'll be doing is blasting gunk into the oil galleys and potentially setting yourself up for bad juju. Also, brake cleaner will thin out the oil quite a bit and cause lots of other issues, especially if it's the chlorinated type. Brake cleaner is strong stuff. If you're not going to pull the valve cover and do it right at this time just hold off, maybe replace the elbows and grommets but don't go poking garbage into the engine or blasting brake cleaner into the engine. Save that for when you can take off the cover and get it cleaned up properly and away from the engine innards.

Heather93yj said:

Definitely! Thank you for your response. I just didn't know if there was a way, like with a way to catch it or something magical of which I wasn't aware. It never hurts to ask, right? The CCV valves are both clean and I put a new air filter in too. I'm hoping to get to it in the next couple of weeks. The good news is I drive fewer than 3 days a week and usually under 20 miles. Thanks again!

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That's definatly not helping with sludge and gunk buildup. Short trips are an engine's nemesis.

I think it will be Better to wait until you can pull the valve cover and do a proper clean. It’s great that you’re taking care of the CCV valves and the air filter in the meantime. When you get a chance, swapping the incorrect part and cleaning the towers should help. I had a similar issue with my 6.7 Cummins where I ignored the CCV filter for too long, and it caused a lot of blow-by. Ended up having to replace it sooner than expected. Better to tackle it when you can.

great information, i hope every thing works. i am to put in keeper file. thanks

Replacing the CCV filter early on can save a lot of headaches down the road. I would say tackling the cleanup as soon as you can to avoid further complications will be a wise take. Thanks.