'69 Merc 75 How to remove crankcase screws?

[saltyfries]

Can anyone tell me how to remove the phillips screws which hold the crankcase halves together of a 1969 Merc 75 (7.5 HP)? There are nuts on the other side which are captured by the casting, so I can't turn those. I've tried heating the screws and using a phillips bit in a ratchet wrench to get more torque, but they won't even budge. I'm afraid of stipping the heads or twisting them off.

 

[Chinewalker]

Re: '69 Merc 75 How to remove crankcase screws?

Get a large Phillips head screwdriver. I have a Craftsman one for that very purpose - the head fits the screws snugly. If that doesn't work, go the handheld impact driver method. A good whack on one of those and they usually kick over...

- Scott

 

[saltyfries]

Re: '69 Merc 75 How to remove crankcase screws?

Thanks for the reply. After I tried those methods without success, I tried to drill off the screw heads since the holes on the castings are through holes. But, a standard HS/cobalt drill wouldn't cut it, so finally I put it on a milling machine and using a carbide end mill, I machined off the screw heads. Now, with the crankcase split, I will still have to cut the nuts with a Dremel cut off wheel and remove the screws. Lots of fun.

 

[saltyfries]

Re: '69 Merc 75 How to remove crankcase screws?

Thanks for the reply. After I tried those methods without success, I tried to drill off the screw heads since the holes on the castings are through holes. But, a standard HS/cobalt drill wouldn't cut it, so finally I put it on a milling machine and using a carbide end mill, I machined off the screw heads. Now, with the crankcase split, I will still have to cut the nuts with a Dremel cut off wheel and remove the screws. Lots of fun.