best thing for the vents is to plug up the little vent and make your fill tube a vent with a 8 inch piece of tubing and put a clamp on k/n filter on top real easy to do.

Open you got any pictures?

Jon

call drew at drew marine # 509 535 3393. this is his trick that he came up with and i don't want to take credit for someone else's idea.

.rebuilt a B/W 71 C's two years ago have three hundred hours on them. Behind twin 's 502. The B/W 71C are primarly used in backhoes and road graders and drag cars. Grafite clutches are good up-grades but, you can get cavalar coated clutches same stuff that bullet proff vest are made of. The hotter the oil get the more the friction the more the clutches will hold.

About the whinning problem the control value assembly is leaking possibley the cast iron housing is worn or scard and causeing the fluid to leak thous the noise at low speed. no real probme just lose a little presser. Try replacing the control valve assembly . the only differentice between the earthmovers and boat is that they use air operated control valve verse a manual operated cable.

Pull the motor to replace the rear seal in the tranny.

Do you have tranny coolers ??. If not put a set on to keep temp. under 300 degers or you will cook clutches.



PS. B/W 71C will easely handl 1500hp if you keep in the water