TR2/3/3A Carbon buildup in an intake manifold and on spark plugs.......

[karls59tr]

Can this be caused in some way by a failed intake manifold gasket?

 

[TFB]

The only senario I can think of is a leaking intake manifold gasket would cause a lean condition that is compensated for my an overly rich fuel mixture.But I think you would also have leaking intake valve allowing some combustion gases into the manifold.
How's the compression?
Tom

 

[karls59tr]

The only senario I can think of is a leaking intake manifold gasket would cause a lean condition that is compensated for my an overly rich fuel mixture.But I think you would also have leaking intake valve allowing some combustion gases into the manifold.
How's the compression?
Tom

Compression is good across all cylinders. What if both intake and exhaust manifolds were leaking because the manifold bolts were loose and the gaskets were not sealing could there be a flow of exhaust gases into the intake there causing a carbon build up in the cylinder head and on the plugs if the engine was running rough?

 

[CJD]

Carbon build up is likely from a rich mixture...which is normal when you start a cold engine with the choke out. Once it is warmed up and you are driving, then it should burn off. If you just started that engine and ran it until you saw the steam under the manifolds, then I would not worry about the carbon. It was running cool and rich. A leaking manifold would induce a lean mixture, which would make starting harder, and raise the idle speed to the point you might not be able to reduce it. A lean mixture normally would not build up carbon.

Wet carbon would be from a mis-firing engine. But yours looks dry to me.