the high initial idle is correct, it's the cold start procedure.

Get your tech to check oil pressure, as the engine warms up this improves thus actuating the VVT - you can lean towards it because I told what it is
But it could also be a blocked oil pick up from old tensioner debris, a lazy tensioner or too long bolts (used the original longer bolts to fit the new tensioners, and blocking the oil gallery that pumps it up)

Go read my first post on the subject, until the engine has been checked out correctly we're speculating.

Hope you get it sorted.

 

Thanks again Sean - yes we are speculating but it has been fun for me.

I am getting more positive feedback on the Jag service shop and owner whom which I am taking the car.

I will keep you and the gang updated of the progress. (pronounced PRO-gress, not PROG-ress).

Cheers!

Bob

 

I'm considering it as a possibility as people who have reported this noise have gone through exhaustive checks of everything at the top end-the tapping noise has been heard on XJ8's & XJR's, and also on engines which have had the 3rd Gen metal tensioners fitted-valve clearances have been checked & found to be within spec etc.

So if everything at the top end has been checked out ok, then that only really leaves the bottom end-but to confirm that is a pretty big job so I don't think many owners will go down that route unless the engine fails in such a way that requires a full bottom-end stripdown.

Most of the posts are from people who simply don't know what the noise is after checking everything at the top end, so that only really leaves the bottom end.

My own engine does not hunt or lope & idles rock-steady. It's got the second-gen tensioners on at the moment but they're not the original set & are still in excellent condition with no cracks or grooves in them. I had the cam covers off & everything seemed fine inside.

On my engine I found the tapping noise quietened down to almost nothing when the oil level was raised about 0.5L over the MAX mark on the dipstick, and a thicker grade oil was used (10W/40 Part-Synthetic).

I did notice that the tapping noise reduced in volume when the car was put in gear, which made me think of the bottom-end. Normally, a tapping noise that's speed-dependent is usually the valve train components. If it's load-dependent, then you're looking at things like piston slap, small-end & big-ends etc.

At the moment the noise is just a nuisance when it's there, but it neither gets better or worse with time. By using a thicker grade oil & raising the dipstick level slightly over the MAX mark, it's pretty-much completely shut up the noise & the engine idles beautifully quietly & smoothly when warm-even after a hard thrash.

My take on it is that since I can't find anything that's obviously broke-I ain't going to fix it

 

I think I'm going to add half quart to mine and see if it will quieten down.

 

Well, once again, mine is NOT a tapping - it is a knock. It is not an annoyance but and indication that something is wrong.

I dropped the car off yesterday at a very well known and respected Jaguar independent shop. Owner has been doing this for 23 years. Knows these cars inside out. Other Jag owners have given him NOTHING but the highest of praise in this area.

He immediately said it was missing on one cyl. Suspects the usual things in that area: spark, timing, etc. but more likely a weak spring, valve or cyl/piston problem. He said it also totally explains the lope.

He said this is NOT the type of knock (or if you insist, tap) that will be undiagnosable.

Man knew his stuff and presented himself in the most humblest of ways.

Good feeling. Will know more in a few days.

 

Thanks for the update Robert, if no codes or lights and from what you say, it's certainly mechanical. It also sounds like the guy knows them.

Hope it's fixed up soon and you post back with the result, fingers crossed it's not expensive

 

OK, a little update here. The highly recommended independent Jag shop owner/head tech has looked at the car.

Compression was low between two cylinders tho he does NOT suspect head gasket. More likely a couple of bent valves. He also says the VVT solenoid is bad on the right side. He suspects about 2K to fix it correctly.

I called the seller and asked a few questions (yes, I kept my cool). I did a little checking on who he said he had taken the car to recently and the mechanic said that he had brought it in specifically because of the knocking issue. The mechanic said he would have to investigate more fully to determine the cause and the owner declined. The owner had told me that the car had always knocked when cold tho I never heard because the engine was never cold when I looked at it.

I totally fell in love with the color, exterior condition, drive, ride, etc. and SHOULD have requested that the car be totally cold on one of my visits. Also, it would have been good to have a good Jag mechanic look it over. If anything, to at least look at the tensioner situation.

I will say that even with the 2K added I am still glad I bought the car. Car is being worked on this week and will be done towards the end of this week or maybe early next week.

Will continue to update.

 

a $2k bill thats not what i was looking forward too, i just replaced my tensioners, and still have my knocking noise like yours Robert

my car shows a Random Misfire Code, with Restricted Performance occasionally popping up, my next area of diagnostics will include compression test, and a look at the oil pickup

 

Yup,...I've seen this before. MANY dishonest people do that, and the fact that there is no CEL, will NEVER stop me from plugging my scanner. If the port is messed up in any way, I WILL walk no matter how "good is the deal". Once I plug my scanner and there is "no codes in the vehicle",....I'll walk. Seller IS hiding something by erasing the codes and/or disconnecting the battery. Whatever he is hiding, it must cost a bundle to fix, and he was not prepared to pay for it, so he is unloading the problem on someone else.

 

I think that mine was actually showing a misfire code also. I hope yours is not what mine is/was.

Oh, that disconnected light thing was a quote from another owner with a similar problem. I see how that was worded wrong. I amended it (on 1/14/2013).

 

I wish I would have had you there.

At this point I will have to work with what I have.

I sent you an email saying that I get to Socal from time to time. I often look at Bentleys when I am out. San Diego, LA, SF usually have a few choices. For a while I got pretty friendly with the owner of the Rolls dealership (located in Pasadena???). He would come down each Saturday morning to the Crystal Cove car show. This was back when it was still being held at the shopping center. Not sure where it is now?

 

today i just noticed something odd on my car, so the tapping noise gets louder as the engine gets to operating temp, so as i got home, i turned off the car went inside for 5 min before leaving again, as i started up the engine. the knock noise was quiet again, so im thinking it may be something with oil pressure, or oil viscosity, it has a fresh oil change with 5w-30 Mobil 1.

does anyone have any hunches as to what this may be? also after driving a bit the knock noise came back to original loudness

 

@Dan, can you post the noise?

 

i will try to remember to take a video when i go out on some runs through town, ill try posting a cold start video and a operating temp video, so you can hear the increase in loudness

 

I did not get any emails from you. I'll check my spam folder. You can PM me here on the forum, I check it daily.

 

I think Crystal cove is still ongoing- however Cars and Coffee in Irvine usually brings about 3-400 cars- the 2nd Saturday every month is British car day FYI.

 

Cove had moved from the shopping center (7ish years ago) to the Ford Building and then to Maquire's.

I bet the Cars and Coffee is the big event now.

 

well i managed to get a cold start video, but on my travel to go to my local shop that lets me use their equipment, i realized i forgot some stuff at home, turned around, as i got closer to my house, taking a right hand turn i noticed my steering was stiff and felt very odd, so i hurried on home, now pulling into my driveway i heard lots of unusual noises as well as my stiff steering. i threw her into the garage quick turned off the car, and noticed a big long stream of coolant from the road and up the driveway, looked underneath and a pool of coolant underneath, dont know where yet as everything is still hot. but i know this isnt the thread for pools of coolant, but i thought i might as well tell my story for why i didnt post a video at operating temp.

Cold Start knock issue

 

Well I certainly hear the knocking. Sounds more like from the back of the engine???

If you developed a coolant leak and the coolant sprayed on the mono belt the belt might be slipping on the power steering pulley. You could see this and the belt would get hot (usually enough to break) after prolonged running.

I will be interested to see what others say about the chatter. My guy said that the exhaust valves in my car were bent, just as he predicted but he expects the rings to be OK. He also suspects and is looking at today the VVT solenoid that is to the front of the valve cover (you can see it in your video)

 

mine does differently. gets quieter on warm up. i doubt it has to do with your oil. if that was the case you would expect it to get quieter as it heats/pressures up. also note that oil pressure usually reaches it's max after about 5 sec of starting the car. it is MHO that if engines did NOT do this they would all wear out secondary to friction with in a short time.