Valve Cover Removal on 4.0-Liter Jeep Engine

Oct. 24, 2013 By Josh Burns
To provide us with more room to work with to get the valve cover off, we started by removing the air box to provide more working space. Since the connection to the PCV valve is already busted so we didnít need to remove that part.

The 4.0-liter inline-six is a very familiar engine to most Jeep owners. Chrysler has since moved on to a new powerplant for the JK Wrangler and Grand Cherokee in the Pentastar 3.6-liter V6, but for decades the straight six powered Jeep models such as the Cherokee, Grand Cherokee, Wagoneer, Comanche and various version of the Wrangler. It is hailed as a bulletproof motor by many, and it still powers many Jeeps on the road and trails today.

Recently while working on a new project vehicle, a 1999 Grand Cherokee that weíll dive into here soon, we ran into a snag and were forced to remove the valve cover on our 4.0-liter motor. There are a number of reason Jeepers will need to do this, whether itís maintenance, replacing a leaky valve gasket, or maybe something as silly as our reason.

Youíll need to remove the throttle and cruise control cable crossing the valve cover, which is held in place with a bracket on the left-hand side of the motor.

While doing an oil change, we found our engine oil cap was stripped, and soon the idea of pulling off the front PCV valve was suggested. The said ďsuggestorĒ made a few tugs on the PCV elbow and part of the brittle plastic broke. While we got the stripped engine oil cap eventually off, the elbow proved to be much more difficult. Having perused a number of Jeep Forums, we realized this is a common issue for owners of the 4.0-liter engine. As we struggled to pry the remaining pieces of the elbow, the brittle plastic just wouldnít come free. We eventually broke it into multiple pieces and used a needle-nose plier to pull the pieces out of the valve cover opening. Sadly, one of the pieces got away. We fiddled around for it, were able to grab it, but then it slipped away and fell into a crevice in the valve cover. So, the next step was removing the valve cover.

The cables are easy to remove, but take time to not break any connecting brackets and guides (as some are plastic pieces).

So, as we said, there are a number of reasons a Jeep owner might need to remove the valve cover. Overall, itís a fairly straightforward process, and since we had to do it we figured a clear-cut how-to would be beneficial to others who needed to do the same. Feel free to add any additional tips if youíve performed the same action in the comment section below. 

Sure, itís only three cables, but it never hurts to mark the order so itís easy to reinstall. 

The fuel rail will likely get in the way not only to access bolts but also when it comes time to remove the cover. Gently lift it off of the guide bolts itís resting on and set it out of the way.

Now itís time to remove the bolts. Of the 15 bolts, most are relatively easy to get to except for the one at the rear back of the cover. A universal joint fitting for your ratchet will make the removal easier.

Although they are all the same size, there are a number of different bolt types used to hold the valve cover in place. Itís best to come up with a system for noting where each bolt goes (see the next image for ours). 

We used a box and pushed each bolt, in order, into it to show us exactly where each one went once itís time for reinstallation.

Thereís no science to getting the valve cover off Ė itís a pain. The rear of the cover got hung up with our Grand Cherokee. It just takes patience, trying different angles, and staying with it to get it off.

With the valve cover off, we tracked down the final piece of our broken PCV elbow. Although it was still stuck in our valve cover, we didnít want this piece falling into the rockers and creating a major issue. 

The old valve cover gasket was still in great shape when we removed the head. If yours is not, the gasket residue will need to be removed off the cover and the block before the cover goes back on. In spite of our old gasket being in great condition, we replaced it with a new one to ensure a proper seal; we suggest you do the same.

With our gasket set and our valve cover securely in place, it was time to install the bolts. Since we kept track of the each boltís position, it was easy to locate where each during reinstallation. 

We installed the bolts in place, finger tightening each of them and then tightening them down in a circular pattern to ensure an even seal. The bolts need to be securely tightened but not over tightened, as this can compromise the gasket seal.

We reinstalled the cables back into place.

With the valve cover securely in place, the air box reinstalled, and our new PCV elbow was installed on the cover (which we seated by lightly tapping it into place with a rubber mallet). The only follow-up was done a week later, checking the valve cover bolts to make sure they were secure.  

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