Expert: tyler boehner - 2/9/2008

Question
hi Jeff,  a friend of mine got a 185 Johnson, mid 80's that was seized.  he suspected pistons, but after checking pistons they looked good. you can put the motor in gear and still turn the prop, but the flywheel won't turn.  what is your thought on this?  also, for my own info, if someone runs a motor with the wrong ratio of oil, or with no oil, can you take out the bearings in the lower end with no sign of damage on the pistons?  like burnt skirts or score lines from heat

Answer
if you can turn the prop in gear without turning the flywheel, the problem is in the gear case.  If the engine is blown, you can still turn the fly wheel from the prop if it is locked in gear.  I would look at the clutch dog in the gear case first.  To check the engine, do a leak down test on all of the cylinders to make sure the block is good before you spend the money to rebuild a gear case.  Best guess is that your shifter is out of wack or your clutch dog is burnt out.  Running with no or low oil gets the whole block too hot.  You warp your rings, pistons, cylinders, distort your rods, toast your bearings, and distort your crank.  Depending on how hot you got it, leak down is still the best test to tell whether you smoked the engine or not.