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| Registered Join Date: Dec 2002 Location: Long Beach, CA 
					Posts: 1,263
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				Cleaning a magnesium crankcase
			 
			I'm fixing a 70 E engine that sat in a car in a barn for many years. Mice moved in, and their byproducts made a mess. Number 6 cylinder fins are very corroded, and the crankcase is kind of nasty looking, especially around nos. 5 and 6.  What is the best way for restoring the appearance? Media tumbling? Do I need to pull the head studs, first? Can anyone suggest a source in Massachusetts, southern NH or RI? Also, the oil in this engine was foul. Are the aqueous parts cleaners ok for magnesium? Last edited by Tom F2; 02-19-2011 at 10:40 AM.. | ||
|  02-19-2011, 10:27 AM | 
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| Registered Join Date: Jul 2001 Location: Portland Oregon 
					Posts: 7,007
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			Tom, I would soda blast the case, followed by a thorough rinsing so you can closely inspect the areas of corrosion for any structural issues. Media tumbling does the best job of giving a finished appearance and you can coat it with Tectyl to prevent further corrosion. We use Ollie's in AZ for media tumbling these things. 
				__________________ Steve Weiner Rennsport Systems Portland Oregon (503) 244-0990 porsche@rennsportsystems.com www.rennsportsystems.com | ||
|  02-19-2011, 10:33 AM | 
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| Registered Join Date: May 2009 Location: Around Boston 
					Posts: 2,050
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			Question. Are there any differences in particle size. Or quality of them. Does is make a difference if the media has been "contaminated" with other metals. Or is a straight forward procedure? Like. Sir.... Can you please media blast my magnesium case and I will pick it up tomorrow? I'm trying to find a shop that can do this around here. I don't want to regret something that I didn't know. Thank you. | ||
|  02-20-2011, 04:54 AM | 
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			You would ask them to soda blast.  It is a one time use medium.  It will not harm the magnesium while cleaning it.  Other medium like glass bead etc. are too rough.
		 
				__________________ Ed 1973.5 T | ||
|  02-20-2011, 05:24 AM | 
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| Registered Join Date: Feb 2000 Location: Dallas, TX 
					Posts: 4,612
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			I assume you are going to get the case machined after it is cleaned, so the shop that does that, should be able to  clean it for you.
		 
				__________________ Neil '73 911S targa | ||
|  02-20-2011, 05:34 AM | 
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| Registered Join Date: Jan 2004 Location: CT 
					Posts: 11,567
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			Do not use any media other than soda. Glass bead will contaminate the oil passages and plug the piston squirters.
		 
				__________________ Tom Butler 1973 RSR Clone 1970 911E 914-6 GT Recreation in Process | ||
|  02-20-2011, 06:33 AM | 
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| Registered Join Date: Dec 2002 Location: Long Beach, CA 
					Posts: 1,263
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			Are the aqueous parts cleaners safe, as a first step? I've used traditional parts cleaners (petroleum based) in the past, but this crankcase is filthy, and needs something more intense.
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|  02-20-2011, 06:53 AM | 
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| Registered Join Date: Dec 2002 Location: Long Beach, CA 
					Posts: 1,263
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			BTW, this crankcase has only 40,000 miles on it, and the no. 1 bearing shows no sign of distortion. So, I am not anticipating that there will be any machine work on the case.
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|  02-20-2011, 06:54 AM | 
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| Registered Join Date: Jan 2011 Location: Gulf Coast FL 
					Posts: 1,486
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			My 2.7 looked like someone basted a 1000 turkeys on it. When it was on the engine stand I sprayed a few rusty nuts and bolts with PB blaster and noticed it cut through the grime most excellently. I cleaned up the real heavy stuff using a wood scraper, a liberal application of PB blaster and paper towels. After was mostly cleaned up I just used my parts washer for the final wash.
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|  02-20-2011, 08:42 AM | 
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