Engine block colour

[Markbhai]

Some time yet before I get around to painting the block but on stripping I can see two potential colours so would like to know the colour of the block when it left the factory.

The car is a 66 230SL. It looks like the colour was a red ochre colour but behind the engine mounts it is black...was it repainted at some point in it's past?

Cheers

Mark.

[Pawel66]

Tried search: "engine block color"?

[Shvegel]

Semi gloss black is correct.  The red is a primer that seals the casting on both the inside and outside before the final black is applied.

[wwheeler]

For the red primer/sealer, use Glyptal 1201. Available from many places.

[Shvegel]

I thought it might be Glyptal.  It is an electric motor primer designed for high temperatures.  It used to be an old racers trick way back when.  The theory was that it would seal any porosity in the casting and the slick surface inside the block would increase oil drain speed back to the pan.

[wwheeler]

I have used it and works well. On my '60 220SE Ponton coupe, it was sprayed with a red primer mostly inside the block and just some overspray on the outer parts. Hence why it is not a solid red on the outer. The manual trans box was also coated on the inside and when that was rebuilt, I replaced it. Not sure Mercedes used Glyptal way back then, but yes something very similar. In fact, when they vatted the block everything came off except the red primer. Pretty tough stuff.

See attached pics. On the engine pics, you can actually see the old remnants of the red primer on the outer block. It was the same on the inside before I painted it with Glypyal. I have also heard that the primary reason Mercedes used the primer was to seal the residual casting sand to the surface so that it would not work its way out and into the engine.