what is this?

ok i had some loud irratic tapping in the valve cover of my 4.0 the other day. sounds like a worn rod bearing but in the head so i took off the valve cover and it looks like the bracket that holds the two rockers together might be tapping the cover. there is evidence of wear on the inside of the cover. any body know what this is or what i should check?:dunno:

The brackets are actually called "bridges" and they hold the "fulcrums"(the half moon shaped piece that the rockers pivot on) in alignment. If the bolts that hold down the bridges/rockers aren't loose then check for excessive wear in the fulcrums. The rockers could also be worn through.

I'm rebuilding my 90' and with only 140k on them they are wore out. I think that was because since the XJ belonged to my dad and he only ran Quakerstate, they just didn't get the proper amount of lubrication. Some of the rockers were almost worn through.

I forgot to add that the new set of rockers/fulcrums/bridges were only $90. Its best if any are bad to just replace them all.

all depends on your way of thinking, some people would say yes and others would say no.

is it pretty visible to tell if those parts are worn? i will have to check it out. the engine only has 111,000 miles, dont know what oil was used but what is the recommended oil for high milage engines?

If u have the money and want to make sure u have no problems for years, change them all.

111k is not many miles even with low quality oil. Check to make sure the rocker arm bolts are torqued to spec. To check the wear, remove the two front rockers and look at the pivot area where they meet the fulcrums, there should not be any galding or ridges that you can feel with your finger. If they are O.K. put them back in the same positions that they were at, retorque and move to the next set. Just for insurance pull each push rod out,(While the rockers are removed) (one at a time)by giving them a slight "jiggle" untill the lifter releases and check to make sure that they are not bent by rolling them on a piece of plate glass, then reinstall if O.K..

Is there any way you could take a picture of the inside of the valve cover and the top of the head, this would help us diagnose this noise.

ya i can try tomorrow night, wife has camera right now.