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I noticed a small amount of white colored material on the back end of my exhaust manifold. Not sure what it is but here are the facts.

My first thinking is it is coolant that somehow made its way onto or near the hot manifold and has vaporized leaving the white powdery look. I did replace the back two studs last year and of course used sealant with the new studs. A pro mechanic helped me. Next, a few months ago I did notice a few, and I mean a small amount of coolant below the manifold on the side of the engine. Only found that when the engine had cooled down and looked at it the next day. Checked the area and couldn't establish where it was from. Did check carefully the head gasket and saw no issues. Yes a pressure check of the coolant system is next. There are no cooling issues with the engine or any obvious leaks including the heater hoses when it's hot or cold.
Any ideas as to what or where other than my ideas?

Thanks.

David

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Since from what I can see it has occurred in 3 areas where the exhaust manifold sees the highest temperatures I wonder but it isn't some sort of heat-degradation of the exhaust manifold paint. For example, notice that none of it shows on the rear ear of the exhaust manifold where it's bolted to the block which is acting as a heat sink and it seems to follow the line of highest likely temperatures.

PS - if indeed it's the paint failure and assuming the manifold was properly prepped and painted with a good quality exhaust manifold paint, perhaps your fuel mixture is a bit lean?