Leaky water pump gasket due to paint...

[Nessmuk]

Back when I had the engine out I painted everything. Apparently the paint on the metal timing cover on the pump side came loose and the coolant found its way under the gasket. The side to the oil was perfect as was the outer side everywhere the coolant doesn't touch. Where the coolant did come in contact with the paint, it came off like it had oil under it.
Glad I'm running a bypass filter. But it's a pia doing the gasket while sweat runs onto your glasses lenses. Everytime I think I've got it all tight and good to go...

 

[Husker6.5]

1) Ethylene glycol (antifreeze/brake fluid) removes paint.

2) NEVER use a painted surface as a sealing surface for gaskets/sealers as they WILL always leak. ALWAYS use bare, clean metal (or whatever the base material is, metal, bakelite, plastic, glass, etc) as the sealing surface.

 

[1994ch]

Good to know thanks for the tip. I learned something today!

 

[Nessmuk]

I've never trouble with paint and oil so long as the paints put on right and cured. This surprised me though. The oil exposed surface was perfect.

 

[Husker6.5]

Coolant is not oil. Coolant contains ethylene glycol which softens/removes paint. Hence, your painted cover seal failed where it came in contact with the coolant, and the bubbled paint then fragmented. That's the paint flakes you found in the oil. The coolant disolved the paint under the gasket, then migrated through that space and caused the seepage.

 

[Nessmuk]

Understood. Was just saying the other surfaces held fine under the gasket. There is also no oil pressure there, and I'm sure that helps, as the gasket material does peel off the paint easy.