Quote:
Originally Posted by Mikael Nielsen
I can see the pictures were pretty bad. I will take new ones tomorrow. I hope I don't need to machine the crank also.
|
That crank absolutely needs to be polished or maybe turned to the next undersize. A quick check is if you can catch/feel your fingernail drag on any of those grooves on the journal, the crank must be machined.
Those journal surfaces are not serviceable as they are. The brown wear mark between the rods bearings indicates long term wear. This crank was not machined properly the last time the engine was built. I would say the bearings are also too tight, but without knowing the condition of the journals beforehand, or knowing if the oil was contaminated, it hard to say why the bearings were moving metal the way they are. The contact patch looks too long on the main bearings, so I suspect the main bolt torques were incorrect. What size are those bearings? Are they marked STD or some undersize on the back side of the shell?
The correct way to figure bearing clearance is to mount new bearings into the main caps and torque them without the crank in place. Measure the internal diameter of the bearing inserts with a dial bore gauge. Use those measurements to determine the exact diameters to machine each crankshaft journal to achieve the desired oil clearance of .0025". That's the way the pros do it. The easy way is to just turn the crank journals to the next undersize, but the actual clearances can be wrong/scattershot doing it that way if the block is out of spec.
Your next job is finding a very good machine shop close to you. Do not order any parts before bringing that crank to a machine shop.