Oil pump drive worm nut

Air or electric may work or the old fashioned way of getting a good close fitting spanner or socket and apply as much leverage as possible with the engine as securely fixed as possible to maximise the effect. Then as force is being applied strike repeatedly in the required direction with a hammer to shock it loose.

Any use of heat may affect the hardening of the oil pump drive and timing pinion.

A bit ofheat is the next thing to try. If you ply a propane torch flame on the crank centre, you can check the heat by a drop of water, (spit),when it sizzles, that will be around 100 C and is not going to do any damage to the integrity of the nut. Thisshould be hot enough to soften any adhesive that may have been used and, as said, a few good smacks on the wrench should get it moving.

Its a thin nut so you need a good fitting socket at least 1/2 inch drive (I use a 3/4inch drive for heavy jobs) and it may be worth grinding off the taper at the entry into the socket ,with the crank positioned about half stroke a good rap with a hide or copper hammer should do it.

i find the hexagon type sockets best for something like that. along with a t-bar. like Robert has already said give it a good sharp wack . wear some eye protection just incase a piece of socket flys off .

A flat ring spanner will bring the force to where you need it rather than offset as with a socket, again as Robert says grind the face of the ring flat to maximise the engagement depth. If heat does not release it, consider a small dremmel grinding disc and sacrifice the nut. grind away at one flat of the nut and it should yield before you have reached the threads. Mask off the surrounding area to prevent the grinding dust getting where you don''t want it. Make sure the bar through you small ends is as large a diameter as poss to prevent bruising to the small end eye. ( a long 1/2" socket extension is good and protect the crankcase mouth too)

Previously peter_stowe wrote:

I am really struggling to get the drive worm nut off the crankshaft of my bike..The engine is on the bench, and I have locked the crank with a bar through the small ends, but no matter how much force I use it will not turn.. I know it is a left hand thread and I turning it the correct way..Has anyone got any tips on this?

I used an electric hot air gun with temperature control for heating stuborn nuts and an Impact driver, socket and club hammer to break the joints.