The way i fixed this leak at the dip stick entry hole in the 3.9L. To adequately access the hole the power steering pump and engine adapter must be removed along with repositioning the ps resevoir. You will need 10mm box end wrench to break loose the ps & adapter bolts Also a swivel end 10mm socket 1/4" drive with at least two 8-10" extentions to loose from the ds front wheel well with the rubber access cover removed.
You will need to clean the dipstick hole and surrounding area very clean with alcohol/high quality low fume brake cleaner. I used q-tips for the hole cleaning. At the single 5mm bolt attaching the tube to the top valve cover, i used washers under and over the sheet sheet welded tab on the tube for support. Tighted valve cover bolt and place one 5mm washer bolt for awaiting tube.
The original little o-ring installed is small and deformed to seal the tube. Through many thermal cycling, dimensional changes occur thus causing leaking from gap at the o-ring and hole. Don't forget to do after valve cover replacement. To aid in sealing, i placed a 1/4" thick rubber washer center drilled less than the tube diameter for tightness and installed it above the o-ring stop and tie wrapped above the washer snug against the stop that is deformed in the tube by increasing sealing surface area.
To installed the tube with the thick rubber washer placed above the o-ring stop and a replacement o-ring on the bottom of the stop. I used Permatex 650F to place/coat a small skin .005-.01" about a half inch below the o-ring stop on tube end and under the rubber washer. At the hole entry, lightly coat down about 1/4" and 1/2" around the hole a little more of a thicker layer to account for the block casting.
With both tube end and block hole are coated, gently guide the tube end into the hole as the tab hole is guided on the valve cover bolt. Lightly press the tube as put the second 5mm washer and nut. Lightly snug 2nd nut and wait an hour for partial silicone curing and then tighten a bit more lightly.
Look at the tube entry, what you should see is little silicone bead around the washer. Reinstall the ps adapter & adapter. To aid ps pump mounting (2 shorts front & 2 longs rear) one top? long bolt had to be pre-installed in pump hole before pump mounting in the adapter guides or there was no clearance from the frame for a loose install.
I hope this helps as an overview. I did this operation with a host of other improvements in sealing on the replacement engine in my 04 LS. While you're down there replace the crank damper seal too.
