Cylinder Head Archeology

[canada karl]

76 530i....on the upper side left on the head is a small black sticker with a gold BMW logo and the lettering DOT-R. Head # is 1 705 784.9. I'm wondering if this is one of those free replacement motors(heads?) that BMW was was offering back in the day when the "thermal reactors" were cracking cylinder heads? I lost the reactors years ago but still managed to blow a gasket(probably cracked head) anyway. Just curious about the sticker and markings. CK

[Mike W.]

It may very well be a replacement, I've seen a bunch of heads but none with that number, nor markings. I'm not sure that BMW really replaced that many heads, I think many made it to 80K to 100K+, which wasn't considered short lived in that era. If it's a thin casting, it's still prone to cracking even if it's not overheated, and even if it's a good casting, it will warp if it is overheated.

[Blaise]

76 530i....on the upper side left on the head is a small black sticker with a gold BMW logo and the lettering DOT-R. Head # is 1 705 784.9. I'm wondering if this is one of those free replacement motors(heads?) that BMW was was offering back in the day when the "thermal reactors" were cracking cylinder heads? I lost the reactors years ago but still managed to blow a gasket(probably cracked head) anyway. Just curious about the sticker and markings. CK

If you decide to replace it....I have an AMC head sitting in my shop.