Hi All
Just trying to sort out the engine of my WM20. The engine is the last part of the restoration and was running really well before dis-assembly but I did see it had a sheared off head bolt.
Yesterday I started to try to remove the remaining bolts and the first one I tried sheared as well!!
Has anybody any good ideas for dealing with the remaining bolts eg heat etc. I have used penetrating oil.
Also with the sheared bolts I plan to drill them out with a tapping size drill and re tap but if that fails has anybody gone to a larger size bolt?
Thanks in advance.
A rather desperate John
You can also try to remove the sheared bolts by getting the MIG-welder out and weld (on high amperes) a larger nut over the sheared bolt, the trick is that the local heat of the weld expands the bolt and loosen it a bit after it has cooled down again. It works sometimes after a few attempts but usually better in aluminum. But it is worth a try to save the original threads.
Or you can do this trick after you removed the heart of the bolt by drilling. Good luck! Michiel
Had to remove a disc from a Japanese bike and the ends of the retaining bolts holes were open to the atmosphere, allowing road crud and water to penetrate every day in it's 15 year life. 4 of the 5 bolts came out with the judicial use of freeing oil, the 5th sheared off leaving a short stump, the depth of the disc casting. I have a 185 amp MIG welder and did what was suggested above. I put a larger nut over it and puddle welded it to the end of the stud. It was still a bugger to get out but it did come eventually. After removal, I ran a tap down all the holes to make sure they were clear.
If the bolt has broken off under the edge of the piece its fastened to, a self-cenering drill bit will let you keep the pilot hole centered and not run-off into the parent material. Use a reverse thread drill bit. Come to think, it might also work for a bolt that is proud of the surface if the guide will fit around the outside of the bolt...
Hi All
Thanks very much for all your advice. For once the gods were with me. Lots of heat released the remaining 8 bolts. To my eye it looked as if they were in with locktite!!!
Very, very carefully drilled a pilot hole in each of the sheared bolts, then drilled with tapping size drill then using one of these plumbers mixed gas blow lamps directed the heat down the hole for a bit. Then very slowly ran taper tap down the hole. Debris just fell to the bottom of the hole. Job done. I think I was very lucky!
Wiring next!!
P.S. Can I just say how lucky I feel to have all this talent and help from you guys at the end of a keyboard.
All the best
John
Ian
Thanks for the torque setting, that was going to be my next question. It doesn't seem to be mentioned in any literature.
Just waiting for a new set of bolts to arrive. I already have a solid gasket in stock on advice from previous posts.
At this rate I might be on the road by Easter!!
Thanks again
John
['Thanks for the torque setting, that was going to be my next question. It doesn't seem to be mentioned in any literature.']
The M20 predates the common use of torque figures...The figure given is something I worked out by looking at various later bikes that have the same diameter head bolts and do have a torque setting, followed by a degree of trial and error under running conditions...Ian
