Well my XK8 has started to knock, tap, click (whatever you decide it is) on start up, usual process is tap tap tap, a bit of a rattle, then all good...well no noise. Seems to be on passenger side (UK)
So going to attempt removal of the cam cover and check out the tensioners. They were replaced by Previous owner in 2006, but car now at 97k miles so maybe they need replacement again? Not a mechanic but I have to count the pennies, some say its an easy job.... Iam hoping so! Initiation by fire I'ld say lol.
Grateful for any tips.

 

Do you mean a short "rattle" that occurs just after starting that almost sounds like it is waiting for oil pressure? I remember that exact noise when I drove my XK6 over a sharp hill - it told me the oil was down to 3 quarts - that oil pan starved the engine when the oil was low and sharp direction changes occurred. Anyway back to the XK8: If so, this seems to happen in cold weather and occured both before and after the tensioner/timing chain replacement on mine. We discussed this several times last year and the best analysis in my opinion was someone who noted that certain oil filters allow the oil to drain back into the pan - well that was the jist of it. Anyway as I recall this noise is pretty much present in all our cars during the real cold weather start ups after a night outside. It never happens on mine when the car has been driven within the last few hours.

You mentioned tap tap noises. I remember being concerned about this until one of the more technical folks here explained that it is normal - has something to do with fuel mixture. I should note that on the left hand drive cars it comes from the passenger side, same side as the air filter. I have to admit I have no idea how much is reversed on right side drive cars, but I'm sure someone will advise us both.

I hope yours is something real easy.

 

While the metal bodied tensioners were introduced in mid 2001, the second generation spring assisted plastic tensioners were still around on parts shelves in 2006. They were still being sold on eBay as late as 2010. Perhaps a quick look under the valve covers is in order.

. . . but a missing or stuck filter back flow is a common problem.

 

Noted your comments will do oil change soon after so will see if filter change helps too, anyway Thursday morning I will be in my garage until whenever! Snow expected too!!! Thanks again for input.

 

Hi, Well got into garage this morning and following the sites fantastic "sticky" stripped the cam covers away, and had a look st the tensioners. They are the newer ones with a metal body but plastic top and bottom. When you put a little pressure on LH side one , there isnt much resistance, and it could be cause of the noise. have ordered new ones should be here tomorrow or saturday. Have left old ones in situ till then. Using the zip tie method. When the old ones are off, will be able to check further, but no sign of damage, just a bit soft sprung. Keep you posted.........

 

I believe the 3rd gen (metallic) tensioners leak down more than the 2nd. Thusly, need to take a couple of seconds to pump back up and rattle lightly in the interim at start and warmup. Not sure if you have a 26 or 27 motor, if 27, it is also likely the VVT.

Over on the X308 forum the sense is to, to quote Aaron Rodgers, "RELAX!" Non-colonials made need to Google his name or Packers.

 

Thanks for that Jim, Did google Aaron Rdger of the Green bay Packers! and I did chill whilst fitting new top tensioner on UK passenger side. Old tensioner which was alloy bodied with redish plastic runners, was complete and not cracked, but piston was defo not right. not a smooth operation at all, felt very notchy. Still have a knock/tick when cold and a bit of a rattle when you blip the accelerator. Will do otherside next weekend, and see if all well under that cam cover. It so difficult to pin point where noise is coming from! lol

 

The metal bodied tensioners work sorta like a ratchet. Oil pressure will push it up as far as it will go but it should not come back down. If you are able to depress the tensioner it is broke.

 

I recently inspected my tensioners and what I found is that the left (facing out) has tension on the top but the one on the right (facing out) the tension is on the bottom so the slack (left) in the chain is on the bottom and the slack (right) side and on the top. I hope that make sense! I hope so I had a time thinking about it.

I was a bit concerned with it myself and asked an expert and he told me that the chains were basically a mirror image images so I had to draw myself a picture to understand it. I guess the reason for the two part numbers making the left and right tensioners different.

 

Hi Jhartz, Just read thread back over and realised your comment re 26 or 27 engine. Point is its a 26, so does this mean it wont be the vvt? Thanks Jeff

 

Thanks Test point, Have replaced and engine is much quieter, but still a tap at cold start. Blip accelerator a few times a little rattle and she purrs beautiful....mmmm Jeff

 

Still have a tap on cold start you may want to get a stethoscope and see if you can narrow it down. After I put my car back together I placed my hand on the TTV and blip it and I could feel it pulse. See if you an feel that pulse when you hear the rattle.

 

Hi Gus + All, Yep I can hear the pulse at the solenoid as the throttle is blipped, then shes quiet. Going to flush and change oil and filter this weekend see if that help. its funny how once Ive blipped the throttle and she runs quiet, she runs quiet all day until left in my garage overnight (its a bit cold here in UK right now, with snow even!), then same again. Hey, guess its all about owning one of these beasts. lol

 

Hi All, Thought I would just wrap this thread up, as Ive cured the noise problem! Got round to doing oil change, but used a good quality flush, then OE Jaguar filter and a slightly higher grade oil Castrol magnatec 10W 40. Anyway now several days in and two hundred miles plus on the clock and NO, yes No, tapping or rattling as you rev on initial start up, no matter how long shes stood. Engine No beating the sound of a beautiful V8. Read about this method of oil change on forum, and I thank all for those comments that helped me. Happy Motoring! Jeff

 

I just took off my valve covers and inspected the tensioners and on both you can depress them pretty easy with your hands. Could that cause the chain to jump a tooth and mess up the timing? It's running like a diesel right now!

 

Do you have metal body tensioners?

 

Yea they both are the metal ones. I found out the timing jumped and I think the valves might have hit. I was turning the crankshaft to get the cam flats lined up and as I was turning them a hit a really hard spot