These are useful and collceted by car blog!
Question: e30 bmw proper preparation of cylinder head/engine for install?
The pictures have nothing to do with the content!!

I am replacing the head gasket on a 1990 BMW 325i, and am getting everything clean for the install. this engine has been burning oil for a couple hundred miles (guide seals shot), and all but one of the pistons is coated in carbon ash deposits, which are very difficult to remove. my dad says use a wire brush, and that it won’t hurt the pistons, but i need a second opinion. one site online said use a plastic cleaning disc on a drill, which sounds kinder on the block than wire.
while scraping off the old head gasket, the scraper i used left very shallow scoring, and i think they can be buffed out with emory cloth, unless there is a better way? there is also a somewhat deep gouge on the head on one of the exhaust flange gasket surfaces, any way to fix this or will the gasket take it up? –i am doing this with the engine in the car in a home garage, so removing the block to be resurfaced is out of the question. the head has been cleaned and resurfaced at a machine shop, and is pretty much ready. any suggestions as to process, brands and technique?

The following is the answer:

Answer by Theneelster
You really don’t want any scrappings or any corrosive materials anywhere near the piston rings (assuming you’re doing this with the pistons still in their sleeves). Leave them in there as is and run seafoam after the installation is complete.

Scoring: use your judgement to ensure the seal is proper (or you’ll be doing it again).

Exhaust flange gouge: if it’s deep enough and the gasket is metal? No. If it’s pliable material it should, but it might still leak. I can’t think of a good way to fix it besides using something like magnum steel, but based on the heat I wouldn’t attempt it.

Give your answer to this question below!