FILENAMES: Lawnboy1.jpg Lawnboy2.jpg DESCRIPTION: These are pictures of a lower bushing repair for a Lawn Boy "D" engine block. Posted by Matt Maguire . Matt provided the following description: ================================================================= Lawn Boy "D" crankcase repair. Sometime back there was a post on the RCM newsgroup about repairing the Lawn Boy "D" engine block when the lower bushing wears out. When this bushing goes, the bottom seal fails and the gas tends to leak out of the crankcase instead of being forced in to the combustion chamber, (this tends to make the mower somewhat "wimpy"). Lawnboy1.JPG shows 2 "D" engine crankcases after boring for roller bearings, the case at the right is bored for a Torrington BH1412 bearing (which is the "F" engine replacement), the case at the left is bored to accept a smaller OD Torrington roller bearing (that's what I was given). Lawnboy2.JPG shows what a typical setup might look like in a horizontal spindle machine, (although the crankcase will fit quite well in a vise or on parallels in a vertical mill). The fix involves removing the lower seal and boring the crankcase to accept a roller bearing like the "F" engine has. The bushing in the "D" crankcase is cast into the case during the die-casting process and is longer than the replacement bearing. The existing bushing must either be bored .015" oversize, or completely bored out because the process of counterboring may loosen the bushing and allow it to bind in the crank bearing area causing the motor to seize. After boring the bushing oversize, the case is counterbored to accept a roller bearing, (as there are several bearings out there with a 7/8" ID I won't give dimensions here). After machining, the bearing and seal are pressed in and you will have a good crankcase again, (I asked the repair shop if they had ever seen the top bushing go bad and the answer was "never"). Again the bearing for the "F" block is a Torrington BH1412, the seal is a CR 8624, type CRW1 with an "R" lip code. Hope this is useful to anyone fixing Lawnboys... Matt Maguire