Header Uninstall Advice Needed

[Helmsy]

So I finally got around to uninstalliing my headers today. I must say first of all it was a lot easier than I expected. Only 3 studs came out but all of the other nuts came off easily.

See the photos following and note that 5 cyliders had a greyish tinge to them whilst one cylinder (IIRC cylinder 3) on the right at the back was quite sooty compared to the rest.

Could this be a slight exhaust leak or a mixture/injector flow/spark difference to the other cylinders.

I also included a pic of the turbo vanes as I have seen this greyish tinge before in another post but cannot find anywhere.

Should I replace all the studs anyway or leave the ones that didn't come out in there?

[DonE]

It seems your engine is running correctly - the gray shows good combustion. To confirm, you should pull the plugs and compare color. The plugs should be more of a tan than gray though (depending on the fuel additives used in OZ). As for the black cylinder, its either a rich injector or oil coming past the rings or valve guides. It doesn't take much oil to discolor plugs or exhaust port. Have you noticed any oil consumption? Take a look at the plug too to confirm its black. Try to change the injector and run it for a couple of days. If the plug blackens again, its oil. If not, it was the injector. Keep your eyes on the AFR's too. I like to run mine a bit rich which blackens the exhaust pipe but the plugs show a dark tan.

Good luck

[Helmsy]

Thanks DonE,

I will pull plugs later and have a look and I was planning to pull the injectors and 'simple' flow test them anyway.

It hasn't been using much oil at all (although I noticed a couple of drops hanging from the front of the engine near the tranny join) but as I have been chasing fueling issues I was worried it may have been the mixture/afr's in one cylinder differing to the others.

Also it may be a coincidence but 2 of the 3 studs which came out were from the cylinder that was black.

[RarlyL8]

Concerning your studs, I clean up the ones that stay on the engine and replace the others with new.