New Xjc Clanking sound
 

Well i have it now. and getting to know its issues and personality.

Im gettin this clanking noise on and off. when the engine is running. i have no idea was it could be. i took off the right valve cover and checked for scoring on the guides dont see anything i will check out the other side this weekend.

what do you guys think?

Might be an un-flat tappet or tappet adjusting shim. As the tappet and/or shim rotate (as they will) the clearance widens and narrows, thus the noise.

Wild guess.

Cheers
DD

Heard that one before.

Couple of thoughts:

1) Early stages I reckon. The tappet guide that is "pressed" into the cylinder head is loose, and rising up with the bucket and gets clobbered by the cam lobe, which smacks it back down again.

2) The whole engine sounds very "tappety", as in, who ever did the tappet adjustment has them too great. That engine should not have that "clatter".

My suggestion is start from scratch, both covers off, measure the gaps you have, write them down, and then set about reshimming them as needed.

Whilst the covers are off, check the bucket guides for damage, that will be the loose one. A "stake down" kit on the exhaust side is a good idea on these S2 engines. I did both sides on all my 6 cyl engines.

I would tend to agree with the others that its a valve train issue of some sort. I would remove both covers and have a very good look around. You cant do much harm levering all the buckets and cam and other bits around looking for slop in them. Recently at work a ds420 limo appeared with a knocking that was very similar. Me and another guy had a look around and couldn't find anything obviously wrong and the owner opted to take it away test his luck. It was back in a week and had stripped the large spline that fits the cam timing gear to the camshaft 'boss' and bent a few valves so we had to take the head off and attend to that. after that I would recommend checking that the gears are not loose or floppy on the cam.

If not a screwdriver is handy to determine where the issue is. I often use a long handle screwdriver like a doctors stethoscope. This is done by placing the blade against the area you want to 'listen' to and the 'butt' against your ear. If you move up and down each rocker cover the sound will get louder as you approach the source, try all different spots to work out where the noise is loudest. This also works well for figuring out where a bearing noise is coming from etc etc. Quite a handy trick!


As other have said I would imagine its a loose bucket or shim issue due to its regularity. Im not sure if these cars have double sets of valve springs or just one, if they have two it could also be a broken or collapsed spring.

Anyway, not meaning to tread on anyone's feet but first I would use the screw driver check to try and work out if the noise is coming from under a rocker cover or not. If not it may be a chain guide or something similar.

Regards,
Jay

I am wondering if it could not be that the timing chain needs a little adjustment. Had a somewhat similar noise coming from the first XJ6 Sovereign I purchased and a little adjustment took the noise away.

took off the valve cover and found that the previous owner had the guides screwed down so it's not that. makes me feel better.
I need to go get a better feeler gauge the one I used was .012-.014 and it slides right on in there with no grab what so ever. I'm able to spin the tappet with my finger.

have new feeler gauge. when one is checking the clearances how do you know what a good measurement is? I can get a .016 in one tappet it's kinda hard but can get it to slide in.
I used a .013 and it slides like there Is nothing there. I'm kinds testing these things out.

I have used 0.012" COLD on the Inlets, with a "firm" feel to the slide in, if that makes sense.

I use 0.014" for the Exhaust, with the same feel.

I did my OLD S Type 3.4 at 013 and 015 a loooooong time ago, NO IDEA why, and the clatter you got, I got, so back to spec.

Time consuming task ahead, but well worth it in the end.

The rotating of a bucket without load on it is normal.

Just be careful with removing and refitting those camshafts, read up on it MANY, MANY times, as bent valves is not fun.

I had an off and on tappetty sound,mainly when the motor was hot, in my series 3,and I put a couple of bottles of a well known friction proofing supplement in with the oil change and the sound disappeared . Mine has the stake down so it wasn't that,and I know to most mechanics it doesn't make sense,and I can say, no one was more surprised than me.