Investigating poor running (pre ignition, top end clatter) on a rebuilt MGB engine that - on removing the timing chain cover- to check the valve timing- that the oil thrower is missing.
Can anyone advise exactly what this circular disc does and what happens if you leave it out?
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All the thrower does is to stop the front oil seal being deluged with oil.
Leaving it out may mean that the oil seal can't cope with the volume of oil that it is being bathed in, in which case it will probably leak a bit.
Engine designers have found that some engines can manage alright without the thrower and it has been deleted as a cost saving measure. I don't know if the MGB can manage OK without it though.
p.s. I like the moniker!
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I should have mentioned why some engines can manage without a thrower. This is often due to improvements in oil seal design. The old seals had a single lip, or sometimes two -- back to front -- one to keep the oil in and the other to keep the dirt out. More modern seals have a screw-thread sealing face which winds the oil in as the crankshaft rotates (like an Archimedes Screw in reverse).
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I wonder if you are asking whether this would cause your problem.sorry if wrong.?
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mech1,
I was trying to say that the missing oil thrower wouldn't cause the problem (because all it does is keep some of the oil away from the crankshaft front seal). Sorry I didn't make that clearer.
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Thanks for the advice - I don't think the missing thrower is directly related to the poor running as the crank timing chain wheel and cam wheel appear to be one cog out (the dots don't line up). Its just that on removing the timing cover the thrower was missing and I need to eliminate literally all possibilities. I'll fit a new one anyway.
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