Spark Plugs are Lying

[ukkid35]

They look fine to me



But one of the exhaust ports is fairly sooty

What would cause that? Faulty fuel injector?

[GreenV8S]

Maybe differences in the alignment of the port affecting the flow of gases such that one surface gets swept more than the other.

[Steve_D]

Possibly a burnt valve allowing unburnt gasses past which then burn in the port.

Steve

[ukkid35]

Steve_D said:

Possibly a burnt valve allowing unburnt gasses past which then burn in the port.

Steve

Unlikely I think as the valves are new (<2000 miles) and the engine was not suffering any power loss at all

[stevieturbo]

What's happened to it this time ?

[ukkid35]

stevieturbo said:

What's happened to it this time ?

Unfortunately, as I predicted, a completely new but known issue killed the engine dead - Aux Drive Shaft Failure

This shaft drives all pumps: water, oil, power steering, and it seems a Woodruf key has failed, although I won't know why until the timing cover is removed

More importantly I don't know is how much damage has occurred

It happened at startup and was shut off shortly after, without ever being under load, so I could be lucky

What do you think is causing the soot in one exhaust port?

[GreenV8S]

ukkid35 said:

What do you think is causing the soot in one exhaust port?

Head gasket failure in the other three cylinders.

I wouldn't pay any attention to it unless you're trying to diagnose some other problem.

[stevieturbo]

ukkid35 said:

What do you think is causing the soot in one exhaust port?

paranoia lol.

If it was running ok, and no signs of a problem...don't go looking for one.

If the plugs are happy, and in general all other aspects look ok...then it probably is ok.

[Coilspring]

It might be a trick of the light, but...

The spark plug on the far right in the picture looks a but different to the other 3 to me. The back of the earth arm looks darker?

[ukkid35]

Coilspring said:

It might be a trick of the light, but...

The spark plug on the far right in the picture looks a but different to the other 3 to me. The back of the earth arm looks darker?

I tried to orient them so they were all as fitted, but that one might be turned slightly, hence the different colouring