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Join Date: Dec 2002
Location: Long Beach, CA
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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.. |
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02-19-2011, 10:27 AM
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Location: Portland Oregon
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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.
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Steve Weiner Rennsport Systems Portland Oregon (503) 244-0990 porsche@rennsportsystems.com www.rennsportsystems.com |
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02-19-2011, 10:33 AM
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Location: Around Boston
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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. |
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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.
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Ed 1973.5 T |
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02-20-2011, 05:24 AM
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Location: Dallas, TX
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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.
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Neil '73 911S targa |
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02-20-2011, 05:34 AM
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Do not use any media other than soda. Glass bead will contaminate the oil passages and plug the piston squirters.
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Tom Butler 1973 RSR Clone 1970 911E 914-6 GT Recreation in Process |
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02-20-2011, 06:33 AM
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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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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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Location: Gulf Coast FL
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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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The Other Woman
