Broken drive shaft 25 hp omc

" my 25 hp evenrudr '77 br

" my 25 hp evenrudr '77 breaks drive shafts at wot on a light boat. why, how to fix?
thanks mikee "

"Mikee.... How many driveshaft

"Mikee.... How many driveshafts have you sheared off on that engine, and how often does this occur?

Joe (30+ Years With OMC)"

" Joe, this the 4th one that b

" Joe, this the 4th one that broke on this engine. What do you think the problem is, so i can get it fixed? "

"Mikee.... The exhaust housing

"Mikee.... The exhaust housing, the long housing that is located between the powerhead and the lower unit may be bent, or the top driveshaft bearing in the lower unit is worn bad.

With the lower unit off and the water pump removed, it would be obvious if the top bearing is worn bad.

The exhaust housing on the other hand is a toughy! OMC allows a offset of 10° on that housing, that is it may be 10° off from being perfectly straight, but no more than that. If that housing is out of line by more than 10°, the shaft will break.

When installing the lower unit, and sliding it up to the exhaust housing, the top sides of the lower unit should be evenly spaced away from the bolting surface of the exhaust housing. Let us know what you find.

Joe "