The mysterious T's of S50.

[TheEnd]

I'm currently making a start on rebuilding a BMW M3 evo engine, S50B32, which has fallen into my hands as a big collections of bits.
The start has been cleaning up the components til I get hold of some proper 0.001mm micrometers to get a completely accurate look at wear etc, the pistons have been decoked, and onto cleaning the block down.

The bores had a rust mist forming but that rubs off clean with dry tissue paper, but there is some worrying marks between cyls 5 and 6




Now these T shaped marks pass straight through to the other side of the wall. no changes in texture or feel, just a dark shadow.
I guess it comes down to 2 things, a mysterous casting inclusion, or an odd hot spot. No pistons show any signs detonation, there are no marks on the skirts, and no scuffs on the bore, so i have a feeling this is a hotspot from within, possibly one of BMW's famous exploding waterpumps has a chunk of impellor stuck in the waterjacket which has heated the metal and and drawn in a little carbon tattoo.

I haven't seen any cutaway blocks so i'm not sure of the patterns inside, but the two T's facing each other at least show some sort of regular arrangement.

Any ideas if that would be the case, or similar sightings maybe of other letters, or even a number?

[Transmitter Man]

I know zilch about BMW engines but prior to the build it's a small cost to have the block sonic checked for cracks.

Your local engine shop should have access to this servce.

Also, it will pay you to also get that block decked to guarantee a good head gasket seal.

Just my 2p.

Been down this avenue with a 30 year old Ford V8 bliock.

Good luck with those letters.

Phil

[Huff]

Could just be a 'chill' or similar item used to hold the sand cores in place during casting. Not that unusual, I'd have thought.