Disappears completely, sooooooooo, I'm thinking probably the idler pulley.

 

Mine changed pitch with the accelerator and didn't disappear. The bearings on both the idler pulley and tensioner pulley were on their way out. The the whine increased in pitch the higher the rpm's. Made it sound like a turbo unit spooling up. A buddy of mine gave me the BMW for my daughter and it came with the whine, he said he'd been trying to troubleshoot it for a while. It's possible that you may be experiencing the early stages of bearing failure and only noticing it at idle. The pulley's are relatively easy to get to, you could pull them and give each a good spin. If they free spin, the bearing is bad, they are packed bearings and should feel somewhat snug but smooth when you spin them.

 

Thank G-d my car doesn't do that.

 

Did he ever pull it apart to determine what was causing the knock? Sounds like a rod slapping up against the side of the pan.

Happened to me on a 67 Camaro. It was only a matter of time before the rod let go and the piston went on it's way. When I pulled the pan, I could not believe how close it was to taking flight.

Scary.

 

Yeah, I'm not sure what that racket is at the beginning of the video. Toward the end of the video it sounds like the car settles in, and there's a distinct pulsing knock. It's hard to say where it's coming from but a similar sound that's coming from the front of the valve cover is the tell tale sign of a bad tensioner.

 

Here are some pics of the tools a friend made up for me. The big bar looks somewhat like the sprocket tensioner tool but was made to hold the Crankshaft while working on the harmonic balance pulley. My sprocket tensioner is the disk with the extended nut on it - worked great with a breaker bar and a deep socket. Cam locks are 3/8 steel bar w/ hardened bolts. I used a small stack of washers under each bolt head to adjust bolt length. The only spec. tools I bought were the shims (could have made my own but couldn't find exact specs) and the crank locking pin.

 

Can you change the upper tensioner without taking the primary ones off?

 

Yes. That is mostly what people on the board are doing.

Some are using the lockdown method, and some are using the zip tie method.

 

Thanks My mechanic and I did not see eye to eye on this one. I talked to Jag and they insisted that all the chains tensioners and guides be replaced. My mech protested that this was not the case and that he is confident that he can change the up tensioner without taking have the engine apart.
You help is much appriciated!

 

No problem.

Just make sure your mechanic understands the importance of, and the methods of maintaining the cam timing. If he has not done this before, you might want to think about whether you want to be the guinea pig. This is because you said he is "confident" not that he "knows from experience".

 

We've all dealt with the dealers and "Certified" shops that recommend more than we think needs to be done, and we have to weigh our trust of them vs our pocketbooks sometimes, but in other cases there's a reason for the recommendation. I bought an XJ8 in October w/ 125k on her and she ran like a top, clean record - everything you hope to find when looking for a used vehicle. My wife took off for a X-country trip from TX to VA and I had no issues with her taking the car a few months back. She got home and I noticed the "Knock" and after a days worth of forum research pretty much had it confirmed as a tensioner. Pics below L-R straight guides both with major center fractures , Drivers side secondary tensioner (major fracture/fell apart), Passenger secondary tensioner (major fracture/missing shoe/fell apart), Primary tensioners (same OEM plastic used on secondary). The only noise I had was at the passenger secondary - no indication of failure at any other point. Unless you pull the timing cover it's almost impossible to inspect any of the other components. The cost of extra parts is an issue, but in my case it and the additional time to do the full job were well worth knowing what I had in there.

 

We my car was really weird it ran like a top we did a fully tune up because i did not know the history of it, and sure enough it really needed one. After the car was assembled again it ran like crap with that tensioner noise. I am just hoping that its only the top one and the performance is not there.

If the tensioner breaks does the car still run ok aside from the noise or did mine slighly jump timing? Or does your car also run and perform rough because the cam tension is just not there?

Thanks

 

if you're experiencing loss of power/performance it's skipped - you're a hare's breath away from totalling the engine, when timing is off valves are not were they should be in relation to the pistons, when they meet it's expensive.