Engine tapping noise
 

I need a little expert opinions on my ‘97 XK8 convertible, so I thank you all in advance.
I had to run on an errand and heard for the first time a rhythmic tapping sound that seemed to correlate to engine RPM. Higher the RPM, the faster and louder the tapping. It subsided a little on turns.
It was nighttime, so I couldn’t see anything under the hood but as best as I can tell, it sounded as if it was coming from the drivers side bank of cylinders.
No smoke; no leaks; no smells; oil/filter changed 3 days ago and the performance is perfect. The tensioners were replaced years ago.
Many ideas on where I should start?

Nick

Clicking noise - easy check on the VVT solenoid
 

Quick check - If it’s a clicking noise, pull the connectors on the VVT solenoids to see if noise goes away. On the AJ26 engine the VVTs are on the front of the engine block.

If not, don’t drive the car, as it could be something as serious as a broken valve spring or a bent rod etc

Just googled this so check out this simple website
https://mechanicbase.com/engine/engine-noises/

Thank you, David.

Possibly something in the accessory drive train - belt, idler/tensioner pulleys and a changing load on the PS pump when turning?

I hope it is an easy one. Wanted to see if you are familiar with the common noise maker Michaelh noted: idler pulley. Though when mine failed it was inaudible at speeds above say 30mph.

John

Thanks for the ideas and suggestions. I disconnected the VVT solenoid with no change. This sounds like a “valve tap”. It is definitely dependent on RPMs.
After reading everything on site and elsewhere about tensioners and noise, there is definitely no “slapping” sound, no loss of power, no smoke etc.

I’m having it towed to the shop today. If it’s major, I really can’t see myself sinking 2-4K into it. Realistically, how much would a 1997 XK8 convertible with 155K on the odometer; 65K on the engine and 10K on the transmission be worth? Serious question.

Nick

$4,000 to $5,000 if car is road worthy and everything works. $2,000 to $3,000 if car has mysterious tapping / knocking noise. But hey, a car that can still get you from point A to point B will always be worth something. With the previous engine and transmission work (investment), I'd certainly be tempted to keep the old gal on the road

Z

Kinda feel like this “old guy” needs a young gal, but we’ll see

Probably only the secondary tensioners were replaced. The primaries could have missing plastic that could cause a tapping/clicking noise.

Engine tapping noise-RESOLVED
 

Ok. So my mechanic puts it up on the lift and finds that the bolts holding the pulley of the power steering pump have loosened (don’t know how) and the pulley had backed away from the pump slightly, which I guess, was producing the engine tapping.
They tightened and checked everything-purring like her old self. Total bill: $54. On a Jaguar, no less. Lowest mechanical bill I’ve ever received on any car I’ve ever owned. Gonna frame the the invoice so maybe it’ll keep me from panicking next time.
Thanks for all the suggestions. Glad you were wrong 😊
Nick

michaelh did mention the PS pump so I would give him the win on this one. ;)

Glad it was cheap and you caught it early.

And your mechanic seems like a keeper.

You’re right Rothwell. Kudos to Michaelh for the call!
Abacus Racing in Virginia Beach does nothing but exotics. Bentleys, Ferrari, Rolls, etc. Pricey, but they know their stuff.
Goodnight to all and thanks again for the help.

Nick

P. S. Did I mention it cost $54? I still can’t get over it!

Panic over - USD54 for peace of mind
 

Well done on getting it sorted so quickly, easily .... and cheaply.

Now you don’t need to worry about that old gal ... until the next time...

Did I just “jinx” it?

Thanks for the mechanic pointer!

I'm over here in Newport News, so it'll be great to have that mechanic name handy if I ever run into trouble on that side of the tunnels.

And with that bill, it sounds like this shop plays fair.