I had a con rod fail on my B43M about 5 years ago, I did exactly what you are planning to do and it is still running fine.
That's very reassuring, thanks!I had a con rod fail on my B43M about 5 years ago, I did exactly what you are planning to do and it is still running fine.
Ok, time to share some of my ignorance... what do I do about the bore if it's egg shaped? Is there a tolerance within which I'm fine to just hone vs. getting it machined?Muriatic acid will dissolve the welded on aluminum on the crank throw. Just soak it for a bit, in a well ventilated area. You need the crank out to do this and you will need it out to measure the bearings properly anyways. I did a kohler a couple of years ago. Took about half an hour. Another tip, When you mike the bores, be sure to measure at the top AND bottom of the cylinders in both directions. Onan cylinders often wear even more egg shaped at the BOTTOM of the bore due to rod angularity mid stroke.
Ray,I agree with dundee222 ... you'll want to remove the crankshaft to clean it up and measure it. It's not that difficult to remove but will require buying, renting, borrowing, and/or making some puller tools to remove the flywheel & timing gear.
I prefer to use lye (heavy duty oven cleaner) to remove aluminum from crankshafts. I think it takes a little longer than muriatic acid but the fumes aren't quite as bad. Still want to use in a well ventilated area though. And if you do go with acid, be careful where you store it. Years ago I left a bottle of muriatic acid in a shed ... not sure if the cap wasn't tight or if the container wasn't completely sealed, but a few days later I noticed that fumes from the acid had caused some light surface rust to form on some shovels and other tools in there.
Measuring the crankshaft journals & cylinders and comparing them to the specs / wear tolerances in the manual will let you know if you can get away with simply replacing the rods, honing the cylinders, and putting in new rings. Or if you'll have to have the crank journals ground for undersize rods and/or have the cylinders bored for oversize pistons/rings.
Test some plastic to make sure the muriatic acid won't eat threw it, then line the block thoroughly so that any spilled muriatic acid can not touch anything other than the crank journal. You don't want it eating the aluminum block. OH and it is a good idea to wear rubber gloves, glasses, and keep some baking soda & water mix handy in case of a spill.I have the same problem(broke rod) and my dad noticed the odd oil readings on his B43g.
I don't know why we have to take the crank out to clean it. I want to replace the rod without taking out what I don't need. I don't even want to put on new rings.
I'll be watching this thread, hope your engine revival goes well