Crankshaft cup plugs

[tpepmeie]

What are your preferred methods for removing the old crank plugs and pressing in new ones? Does anyone have a tool for that?
Todd


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[CamP]

That's probably a good question for Graham.

When pulling seals in motorcycle engines, I drill a small hole in them, then screw in a sheet metal or wood screw. Then grab the screw with vice grips and pull it out. That might work with crank plugs.

[CamP]

Something like this core plug remover.
https://i.stack.imgur.com/97OhC.jpg

[Jagdpanzer]

For removing the plugs use a straight 1/2" rod approximately 20" +_ long with one end rounded off so it makes contact with approximately 10 mm of the cup center. Starting with the rear cup hammer the rod through until all cups are removed.
For installing use LT5 special tools J-37306, J-38837, Loctite 620 and follow FSM instructions.


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[GOLDCYLON]

If you are stroking the motor and you have done crank work I highly recommend welding the non threaded expansion ones. My first 380 dropped a expansion plug mins after the engine was installed using the right Kent Moore tools.

[CamP]

Originally Posted by GOLDCYLON

If you are stroking the motor and you have done crank work I highly recommend welding the non threaded expansion ones. My first 380 dropped a expansion plug mins after the engine was installed using the right Kent Moore tools.

It doesn't seem to be a common failure, but I've heard of two. One was a stroked stock crank that was apparently nitrided with the plugs in place and developed a rear plug leak. Nitriding may have annealed the plug, or maybe the heat simply melted out enough loctite 620 to leak. Who knows?

The other was a stock crank that threw out one of the npt plugs. That's really odd.

The FSM mentions removing the plugs to clean the oil passages in the crank, but doesn't go into much detail at all. Seems like an important step that is usually overlooked.

[WARP TEN]

Originally Posted by CamP

That's probably a good question for Graham.....

Or Marc Haibeck. --Bob

[CamP]

Originally Posted by WARP TEN

Or Marc Haibeck. --Bob

Marc is wealth of knowledge too.

I think Phil has the answer here. He really helped me out recently with an unobtainable part. Great guy!

[grahambehan]

Phil has a correct answer. The only things i would add, when replacing stock plugs the kent moore tool is correct, when fitting aftermarket plugs it may not be depending on plug width. Also stock is 0.866 plug diameter, typical aftermarket cranks are .875 and plug widths differ.
Graham

[GOLDCYLON]

Originally Posted by CamP

It doesn't seem to be a common failure, but I've heard of two. One was a stroked stock crank that was apparently nitrided with the plugs in place and developed a rear plug leak. Nitriding may have annealed the plug, or maybe the heat simply melted out enough loctite 620 to leak. Who knows?

The other was a stock crank that threw out one of the npt plugs. That's really odd.

The FSM mentions removing the plugs to clean the oil passages in the crank, but doesn't go into much detail at all. Seems like an important step that is usually overlooked.

I will never take that chance again. They should have been all treaded in the first place from the factory. It's my best advise and something easy to do while you are in there.