Hi Steverat...If any single aspect of the design of the A10 has ever been neglected or misunderstood, it is the "Sludge Trap". On a small journal crank it really is just just a simple oilway leading from one big end to the other. Unfortunately this is where all the low life found in your motor congregates to cause trouble. This is how I do small journal cranks. Basic technique applies to big journal cranks, but they have a tubular trap that really does trap the sludge.
I will assume you have some basic knowledge, you may be a time served machinist, apologies if this is a trip down memory lane.
First, measure the journals. Has the crank any life left? Is it worth proceeding. Can you get new bearing shells?
If your plugs have no slots, that is unusual. How would they be turned into place? Could they be some just some bodge by a previous owner, like a couple of metal corks hammered in?
Have a good dig, there should be a slot across the middle, plus 2 or 3 punch marks to lock the plug in place.
Getting them out is easy. First treat yourself to a new set of drills. My favourites are a cheap set of cobalt drills from Toolstation.
Support the crank well, and talk to it. Let it know you have a new set of drills, you are in no mood to be gentle, the end of the world is coming, and you, plug with no married parents, are coming out.
The aim is to create the least amount of damage, so we start gently and work up into a frenzy of violence and desperation no plug can resist.
Next, drill very gently into the punch marks with your smallest drill. The aim should be to remove metal from the plug, not the crank. When you have done some exploring, drill the punch marks with bigger drills until you are sure they are no longer effective, making sure you do not drill the crank.
Now you need the biggest flat blade screwdriver......I use one on a 1/2" square socket drive. With the crank well supported, put the blade in the slot and give it a good smack to let the plug know the pain is coming and jarr the thread and hopefully help start it on its way out. No luck? Try an impact driver, but the blade size on these is smaller and you may damage the slot.
Next, try a bit of heat. Butane, Propane torch, Oxy- acetylene if you have it. This is where I generally have success and out it comes, normal right hand threat, lefty loosey anti clockwise to undo.
No slot, or slot already wrecked? Drill a nice hole in the middle but do not use a stud extractor. Typically these spread the plug further the deeper they go so will tend to make it more difficult to remove.. Instead try a big TORX bit, hammered into a slightly smaller hole. Still no good? If you feel confident, put a bolt in the hole and and tack weld it to the plug. The heat of welding a bolt to the plug will help loosen it and you also have something to put a spanner on.
Still no good? Big Drill Time!. Enlarge the centre hole with your ever increasing size selection of new drills until you are left with just a thin threaded cylinder, thin enough to collapse into the hole.
Remember, try not to damage the crank. Before grabbing a well deserved beer, take a few pictures to remind you of one of the most memorable days of your life.
You will be amazed at the small size of the oilway. Easy to clean, just a straight drilling. New plugs are available, or get some made, thread size somewhere on this Forum.
Good Luck with it.
Keep Spannering, Swarfy.
