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Crankshaft locking up
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thornebt
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November 26, 2018 - 10:47 am
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My crankcases fitted together fine and the crank rotated freely.  However, when I inserted the main bearing oil seal on the timing side it seems that the crankshaft oil seal comes up against the oil drag fan and stops the crankshaft from turning.  There's clearly something wrong here as the internal lip of the seal is about 28mm, the diameter of the crankshaft is about 19mm!  

I must have the wrong oil seal?  This is really confusing!  Cheers.  Bruce.  [Permission to view this image is denied]

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thornebt
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November 26, 2018 - 11:01 am
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I'm a complete idiot!  I think I've worked out that the oil seal I've put in shouldn't be there at all?  There should just be the smaller oil seal on the outside of the crankcase.  The oil seal came in a kit for D1 engine but maybe it's only for D3 engines? 

But if someone would kindly confirm that I'd be grateful.

Cheers.  Bruce.

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Blue Heeler
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November 26, 2018 - 12:52 pm
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That`s right oil fan is to fling mix out to the bearing....and it can`t do that with a seal in the way. 

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Piquet
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November 26, 2018 - 2:20 pm
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Have a look here

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There appears to be 3 different arrangements for the oils seals on 3-speed engines. This is my understanding of the different systems.

Very early engines (D1) had only an outer seal on the generator side and a seal between the bearings on the drive side, inner main bearings lubricated by petroil mix from drillings at the bottom of the transfer ports.

The next engines (D1, D3), from about 1954 still used only an outer seal on the generator side and the drive side seal was moved to between the crank and bearings. Drive side bearings were lubricated by gearbox/primary drive oil and the generator side was lubricated by petroil mix supplied by a transfer drilling and the fan drawing the petroil mix through. There also appears to be two different arrangements to position the generator side seal, earlier engines used a distance piece and no fan, later engines used a fan to assist with lubrication and the seal was positioned by a circlip to avoid covering the transfer drilling.

Later still, 1958 perhaps? (D1, D5, D7), the arrangement stayed the same on the drive side but the generator side now used 2 oil seals either side of the main bearing which was now lubricated by gearbox oil the same as the drive side.

Information seems to be confusing to say the least and the Parts books don't help as I'm sure they don't list all the seals in all cases!

Further information/confirmation gratefully received will be added to the above FAQ section.

I'm not a complete idiot ............................................ some parts are missing.

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thornebt
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November 26, 2018 - 3:10 pm
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Thank you Blue Heeler and Piquet.  I removed the oil seal and the engine is now back together and the crankshaft, as you would expect, now rotates perfectly.

I didn't even have any bits left over!  I must be getting better at this engine rebuild stuff.

The fiddliest bit was when the kickstart return spring managed to escape its proper location (twice!) after I had fitted the clutch.  I managed to get it fitted correctly but it's a lot harder with the clutch fitted isn't it!

Cheers.  Bruce.

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