How to repair a leaking valve cover on a Jeep 4.0

How to repair a leaking valve cover on a Jeep 4.0

The early Jeep 4.0 valve cover is sealed with RTV silicone. However after 1995, Jeep used a rubber coated metal gasket. Be sure to get the right seal before removing the valve cover to repair a leak. The proper silicone is oil resistant. You can get it from a Jeep Dealer or from some aftermarket suppliers such as Crown Automotive.

Begin by removing the cables going to the throttle body. These unclip from the throttle body and the bracket between the throttle body and the valve cover. Label them and lay them aside.

Remove the crankcase vent tubes.

Next, remove the hose supports and spark plug wire holders that may be attached to the longer studs of the valve cover retaining bolts.

Make a cardboard or Styrofoam template of the valve cover and use this template to keep track of the various types of bolts used to secure the cover. They need to be installed in the same holes they came out of.

Remove all the bolts. They are typically 11mm and you will need a deep well socket for the studs. On the Cherokee, there is one in the back near the firewall that can be difficult to access. I use a 3/8 drive socket mounted on a universal joint to access it.

With all the bolts out, carefully bump the cover with your hand or a rubber hammer to break the seal. Carefully lift it off the head taking care not to drop trash into the valve area.

Scrape off the old gasket material. If you are working the earlier RTV type seal, a Scotchbrite wheel on a drill can be helpful to clean the cover. I mount mine in my drill press to make it easier to handle.

Clean the head mounting surface as well.

For the gasket style, simply place the gasket on the head. Pay attention to the two locating dowels to make sure the gasket is properly aligned. For the RTV style, apply a thick even bead of silicone to the cover and let it sit for about five minutes before installing the cover.

Set the cover in place and make sure it is aligned properly. Make sure that none of the wires or other tabs are trapped between the cover and the head.

Using your template, put the bolts and studs back into the holes they came from. Tighten them snugly but not too tight. These are small bolts.

Replace the holders on the studs and put back any nuts that were removed.
Reconnect the cables to the throttle body.

Reconnect the crankcase vent lines.

Take a moment to check for any other lines that may have been knocked out of place. It is easy to pop out the line to the MAP sensor or the fuel pressure regulator while removing or replacing the valve cover.

The gasket style can be started immediately and checked for leaks. The RTV style needs to set at least half and hour before starting.