I have just been told by my trusty mechanic that my spark plugs are coated in oil and that I need my gaskets changed - on both sides. He has quoted me a price of $385.00 to fix - are these hard to replace? Is this a job that maybe I could do - not being mechanically minded?

Also - is this why my engine light/rest performance light keeps coming on? My OBDII reader keeps telling me that one of my knock sensors needs replacing. One of the jag mechanics told me that the XJR's suffer from vaccum problems???? The Rest performance light is so annoying. One day it won't come up and I can drive for 100 miles - the next day it is intermittent and just won't go away ( God this car has my life!!!!

Any help guys - greatly appreciated.

Steve (2001 XJR - 91500 Miles)

 

Oil on plugs = valve cover gaskets/o-rings... my opinion if you paid the mechanic to change your plugs you may want to pay him/her to change the gaskets.

 

Yes the Aj26 motor is notorious for valve cover leakage and that may cause your ECU to think that your knock sensors need replacing if its missing bad enough under moderate to heavy load.

It's not a difficult job to do as long as you follow the guide and are patient. Be very careful torqueing down the bolts and the sequence they are tightened. The bolt retaining rings actually hold the gaskets in place so it's not too bad. No need to use sealer except at the very small seams at the front of the heads. Figure a 5 hour job unless you have done these before.

Vacuum hoses tend to crack and cause leaks on these cars. It's just a matter of replacing the hose.

 

x2.....

 

Why do need a mechanic to change plugs in this situation? A leaky valve cover gasket covers the oil on the outside, it doesn't cause oil fouling. You don't need to remove the plugs to change the gasket, just the coils. You also don't need to remove the valve covers to change the plugs. The mechanic is still going to charge the same amount of labor whether they change the plugs or not.