7.4 exhaust manifold paint

[kschnebly]

I'm blasting and painting my manifolds on a gen 5 7.4. Is 500 degree ceramic coating sufficient? I'm mostly curious about the elbows at the head connection.

 

[scoflaw]

If your talking about manifolds at the heads, I doubt it. Merc can't even get paint to stick there.

 

[Bt Doctur]

maybe Hi-Temp engine header paint?

 

[wingless]

If the paint is shot, then the exhaust parts probably are also past end of life.

Inspect the raw water passages for excessive corrosion.

Inspect the mating surfaces for sufficient SOLID wall thickness between the raw water and the exhaust gas passages.

My new Mercruiser parts are painted w/ Rustoleum Professional aerosol w/ great results.

 

[Lou C]

They should never get that hot that they would need header paint, in fact I asked about this (since in salt water not being able to flush I'm now up to exhaust system #4 on the same boat!) and the header paint manufacturer said the water cooled manifolds probably would not get hot enough to cure the paint fully. So I just used regular engine enamel on my OMC batwings and when I switched to the 2 piece center riser style (Volvo Penta style) I just re-painted the new Barr exhaust I got with Rustoleum brush on since the paint they came with was too thin to last. As long as I did not have an overheat I never had trouble with regular paint burning off but maybe the OMC/Volvo exhaust system design runs the manifolds and elbows cooler since they get water right from the thermostat housing with no poppet valves etc like Merc uses. In fact my OMC batwings used to run at about 100* at idle and they most they would hit was 135* after coming off plane.

 

[scoflaw]

Obviously your not familiar with BBC manifolds. There is no water jacket on the manifold where it attaches to the head.

That be the area that don't hold paint