Sometimes the journey is just as important as the destination.

 

If you have a dropped valve seat is there a loss of power or rough running?

 

In my case (with apparently two dropped valves) the car surprisingly was quite springy, though obviously wounded. The most noticeable sign was fairly strong cluttering sound. I like the description somebody provided earlier: a noise similar to a large sewing machine might produce

 

My 1992 XJR-S has developed a tapping noise from 6B, and I fear the worst. It was intermittent and has become more persistent. Initially it did it only under acceleration and not at idle or steady speeds but it seems to be getting a bit worse. Odd thing is that if I pull the plug lead on 6B the noise stops.

I'm hoping it's an exhaust leak around the plug or something like that, and have bought replacement plugs. THe noise very much seems to be coming from inside the V rather than the exhaust manifold...

Video:
https://www.youtube.com/watch?v=kWIz...ature=youtu.be

It really does sound more exhaust-y to me.

 

If you pull the plug and the knocking stops it's usually a rod bearing.

Video does not sound like a rod to me.

 

Sounds like a leaky gasket... So not a really fun job to replace (not much space at all).

 

It really does sound like that doesn't it

 

What gasket?

I don't see how any exhaust leak jibes with pulling the 6B lead silencing the noise. Unless the exhaust manifold gasket has blown out on one cylinder.

 

Exhaust manifold gasket (between head and manifold)...

 

gasket, thanks I will file this video for sound of exhaust gasket blown at head to manifold...

 

OK this was many years ago but this might be useful.

I was totally confused by this noise, it sounded for all the world like an exhaust manifold blow but it was inside the V on the inlet manifold side.

Turns out that on cars that don't have secondary air injection the ports for the SAI system are blanked by the inlet manifold gasket, and they can develop a blow. Pulling the plug got rid of the noise for obvious reasons.

Inlets off, easy enough job, and you could see the blow on the gasket. Couple of hours work and very little cost and the car was fixed.