Reviews for Crown Automotive 33001016AL Oil Fill Cap for Aluminum Valve Cover
If you bought the Crown 4.0 cover, you need a couple of these extra on the shelf. These will fail every now and then by: Shrink so that they do not fit tight anymore. Crack/break as you pull it out after it gets a couple of years on. Fair review though, I've had the original factory one break and crack too. So this part is a good investment overall on your Jeep 4.0.
Does the job for your 4L in-6.. Aluminum Valve cover. This is the second one I have bought and you generally will get about two years out of one if you drive your Jeep as a daily. They will eventually melt and loose their seal. But if it can hold up to Australias temperatures and my long road trips. It's a five star rating from me.
As specified
good replacement cap for omix aluminum valve cover
Same as original, wish they made a locking one.
Works great when new but will lose its seal or break (like mine) after about a year. The best solution I have found is just to go to Home Depot and buy a rubber plug.