Ok. This one is tough. I have a 4.2 liter 6-cylinder engine in my series 2 XKE. Recently it developed a metal-to-metal tapping in the engine, but only at idle speeds. Tapping is intermittent. Maybe once per second, and doesn't seem to be directly related to engine rpm. My local mechanic used the equivalent of a doctor's stethoscope, and said it seemed like it was coming from the driver's side cam, between the 2nd and 3rd cylinder. Car/engine have only 18,600 miles. He gave me a can of Sea Foam told me to fill the gas tank (which I did), and drive it for awhile.

Any ideas anyone?

Thanks in advance.

Submitted by rgrisar@hotmail.com on Wed, 09/12/2012 - 11:36

Tapping solved.

Thank you George and William.

The problem was a loose tappet guide striking the cam lobe, once the engine reached operating temperature. Removing the cam cover revealed the minor damage to the guide. A valve guide stake down kit was installed, and as an additional precaution, the engine oil and filter were changed (reducing the risk of small shavings from tapping the head for hold down screws. Of course, once the cams were removed, we installed hold downs on ALL the guides.

It was your tip William that lead to a well-written article on Jag-Lovers by Lawrence Buja
southernatncar.ucar.edu titled XK Engine Tappet Retainer Stake Down.

Submitted by rgrisar@hotmail.com on Thu, 08/16/2012 - 12:51

Hello George.

Thank you for responding so quickly. George. The compression is 165 psi in 5 cylinders, and 160 in the 6th. The oil pressure is 60 psi.

The metal-to-metal knock is intermittent. When active, it sounds like a wrench banging against an anvil, about once per second. Seems to be independent of the engine rpm. My local mechanic says it is in the left bank (as viewed from the back of the car), between 4th and 5th cylinders, about two inches below the cam cover. He also suggests the cause is piston slap.

Per his suggestion, I have added a can of Sea Foam to the gas tank, and filled with 10 gallons of premium. Any other ideas or guesses?

Thanks in advance. Best regards, Bob G

Submitted by SE98-32482CJ on Mon, 08/13/2012 - 23:28

Robert I think I would pull the cam cover on the exhaust side and do an inspection. If all is well there I would look lower. The comment that it is intermittent is an issue but you could have piston slap. What is your oil pressure and what is your compression?

Submitted by redbil@aol.com on Mon, 08/13/2012 - 20:48

I have an off the wall idea; please do not laugh. The tapping occurs at idle in neutral at less than engine speed That would seem to point elsewhere from the engine. Assuming things are not moving, sheet metal and heat shield banging seems unlikely. Between cylinders 2 and 3 (remember 1 is at the rear) puts the source next to the heater. Any chance the impeller is turning and hitting something? A second possibility may be an exhaust bang but that would not be localized high on the engine.

This is a long shot but easy to check.

Bill