I need a little help I have a 525efi with a bravo drive and engine coupler. The old motor had a pilot bushing in the end of the crankshaft. I called Mercury racing tech support and asked them if it was required due to the fact that the engine coupler is solid and the pilot bushing is used for keeping a shaft in alignment with the crankshaft. I talked with bret and he said it is required to bolt the bell housing on. WOW!!! it seems to me it serves no purpose.

i think the merc tech is wrong.i have taken a lot of merc engines apart and never seen a pilot bearing.

I would like to hear his reason why the pilot bushing in the crank affects the bell housing. as far as I know the bell housing is never in contact with the crank (if it is then you probably have bigger problems than just the pilot bushing)

my guess is he was thinking about the dowell pins used for bell housing alignment.

A pilot bushing is required if the motor is not a rear plug in... Meaning if its a staggered engine or has a drive shaft. i have replaced many of them in forward motors. they do wear out and get sloppy.

the bushing is absolute necessity in some trans setups. the length of contact between coupler and input shaft is shorter than on a clutch disk. but you have a good 2 inches of mating surface along the length of the coupler splines on a bravo-alpha. that being said, if i had a pilot bushing to use, i would install it. the worst it can do is keep the shaft runout down to essentially zero.

the op has a bravo drive.the input shaft on a bravo drive does not have a machined surface to fit in a pilot bearing nor is the shaft long enough to go into a pilot bearing.this is not a transmission application so i don,t see a pilot bearing doing anything in this application.

Part #13 in this diagram. Crankshaft pilot bushing. Used on driveline style setups, like in a staggered engine setup or triple engine setup? Is that what you guys are talking about?

http://www.mercruiserparts.com/Show_...ler+Components

I would like to thank all of you for your imput. The coupler is solid in the center and would not allow the shaft to even come close to the crank so I did not install it. HAve a safe and happy forth of July