Hey I am looking for a way to clean my 911 block and chain housings. I know the block is magnesium and I think the chain housing are as well? Anyway, what is the best way to clean them up without taking everything apart and having it hot tanked or media blasted?

elbow grease and time brother.. some products work better than others, some cost more than others but in the end it is effort that prevails..

I have used , laundry soap and stiff brissle brushes (with nylon/non organic brissles)....and also MAG wheel cleaner, but with magnesum you have got to stay on top of the degressing process. this means spray on the cleaner,brush/and rub it in/and wash it off. with some mag wheel cleaners it will DARKEN the magnesium and or aluminum if you leave it on too long (20-30 )minutes. It does cut off the crud, and with the high pressure car wash pressure washer the grease and crud is gone...and neutrilizing the mag wheel cleaner is a breeze Tip don't run out of quarters, or dollar bills.plan on 10-12 bucks.(may take six-6.)...best part...when done you can just drive off, no clean-up.....Hot tank is equivalant to "steam cleaning" temperature wise. steam-cleaning will warp the block/or heads etc. Media blasting?...that would be a disaster.

I second the pressure washer hooked up to your hot water line. I connected a garden hose to my laundry sink in the basement and ran the hose out the basemant window. Hooked up the other end to the pressure washer. Started with Gunk engine degreaser followed with Dawn dish soap and a scrub brush. The pressure washed saved a lot of elbow grease and scraping.

I second the laudry soap and nylon brushes or beatr up scrub pads.. The chemicals are not cost efffective only 1/2 of them work 1/2 the time then as stated you could discolor stain the case even after you thought you got it all off.. The fastest is the yellow can easy off oven cleaner no kidding it will clean it in seconds but it will remove paint, anodizing and every and anything else, screws up plastic ect.. at your own risk. plus think about it when your done and if any chemical is left on there you going to heat it up when you drive and what would that do with what chemical reaction..

Read the warning on the can of oven cleaner. It says not to use it on aluminum.

How about haveing it steamed cleaned to get the bulk of the grime off it? Usually places that do undercoating like Ziebart have the steam cleaners.

............... Please pay attention....heads up..."steam cleaning " WILL WARP an ENGINE BLOCK, HEADS, ALUMINUM parts........BECAUSE it puts a very high localized temperature on ONE section of the component as you are cleaning.....You can destroy the machined tolarances,and you will not realize it unless you pay attention during reassembly of the engine....This is not to say it it won't bolt back together. IT,s just a lot more difficult for the case halves to,mate, slide together,fit, snug up,in a natural sort of way.(it,s a you gotta feel it sort of thing)...steam cleaning of sheetmetal is OK.....

WD-40.... crazy as it souds, I helped a kid with a 65 mustang the other day and that's all I had. It broke down the grime faster than any other cleaner I've tried and came right off with the pressure washer.

Castrol super purple works wonders for grease to. I think you will need a combination of things to get it.
Keep in mind electronics if any when you pressure wash. Cars get towed to dealerships every monday from someone pressure washing over the weekend. It ends up taking out sensors and connectors!