Hi Guys,
LTNS, I know …
Things in general have been running smoothly with Harlem, although I am concerned over an engine noise I first noticed last week. I had popped the hood with the engine running to replace a blown headlight bulb in the middle of the night, and noticed that the top area of the engine @ (the “A” bank, driver’s side) was emitting a regular, even “swoosh swoosh” kinda sound in time with the engine, kinda like a threshing or sewing machine. 
I noticed the last few days I can hear the sound now sometimes even with the hood closed, when I’m near a building that reflects sound, like when I’m idling while going through the drive-thru at a fast-food joint. I have had a tech buddy of mine give it a listen to, and he says it is definitely in the top area of that bank and believes it is something in the valve train there, not in the block )phew!). He said he would return to check it again with his mechanic’s stethoscope, to try to pin it down better. He also clarified that it was not a water pump or alternator bearing issue (I had asked).
Any idea what this sound might be, and should I be concerned? 
At first I wondered if it might be the dreaded timing chain tensioner or chain thing, but I wouldn’t think it would make a noise like that if so. The only other thing I can think of is maybe a sticking valve, so I have tried adding a can of STP High Mileage Engine Treatment + Stop lLeak (I do have to add about 1 quart of oil every 1,000 miles, btw) as it claims it will “quiet” noisy valves/lifters (notice they never say “frees” or “helps free” sticky ones anymore, btw?). We’ll see after a few days of additional driving if that makes a change in the sound or not. In the meantime, the car continues to run fine and no check engine light, although my gas mileage seems to have dropped off a bit, from an average of 16+ MPG to under 14.
btw, I know Jags used to always use mechanical lifters, but did Jag go to hydraulic ones with the X-308s? If not, maybe time for a valve adjustment @ 175K miles ?
