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Registered
Join Date: Aug 2020
Posts: 109
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Crankcase mating surface shiny or dull?
I am rebuilding my 2.7 mag motor.
The old casing sealant has been removed but the mating surface is a dull grey however I can scrub it back to shiny. Is this necessary for a good seal? I don't want to damage it if I can leave as is. Cheers! |
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08-28-2021, 06:34 AM
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Ingenieur
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The answer is - no. As new they came with a zinc dichromate coating, which is a sort of dull gray. Aggressive cleaning will remove it and the surface will then appear shinier. It is not uncommon to see both on a case mating surface, patches of gray, and also shinier areas.
Last edited by Speedy Squirrel; 08-29-2021 at 01:17 PM.. |
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08-28-2021, 09:07 AM
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Registered
Join Date: Aug 2020
Posts: 109
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Great thanks. I shall make sure they are cleaned and degreased and not go too crazy trying to get them shiny.
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08-28-2021, 09:16 AM
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It's a 914 ...
Join Date: Jan 2008
Location: Ossining, NY
Posts: 4,703
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Do clean thoroughly of course, but I've never heard anyone say shiny or dull is preferable for a proper seal.
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08-28-2021, 06:59 PM
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Registered
Join Date: Jan 2003
Location: Langley,B.C.
Posts: 11,994
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Ensure the surfaces are flat....
As you are rebuilding a Mag case motor, I trust all appropriate machine work had been done? Align bore check/machining, case mating surfaces trued, case savers/timeserts installed, maybe dowel pins, spigot bores trued etc?? If not, don't worry too much about which surface finish is appropriate for the mating surfaces.... Cheers
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08-31-2021, 09:51 PM
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