Re: How to change a prop
I'll bite.
Current engines have a nut, locking device for the nut, prop ( including hub), thrust washer, and propshaft. The propshaft is splined to interface with the splines of the prop hub.
Older engines, and some current (low horsepower) engines (possibly) still use the "shear pin" system. This is for a smooth propshaft with 2 holes in it. You have a hub cover with "cotter" type locking pin, under which is a dowel pin (usually bronze) that goes thru the propshaft and fits into a detent in the rear of the hub. Then the prop, then the thrust washer. This system is undesirable on larger engines as striking objects with the prop blade usually results in shearing the dowel (pin, hence the nickname "shear-pin") and renders your engine immediately useless. The shear pin must fit snugly into the detent in the prop to work effecively, so prop hub thickness is very important.
In saltwater you want to keep everything lubed up good. Lubriplate white grease is excellent as is Merc teflon loaded grease, and other OEM's have theirs too. Grease the shaft/splines prior to reinstalling. Annual lube is highly recommended, regardless of water type.
You always want to insure that you have a properly installed thrust washer. Looking at the ID of the washer, it is tapered. Proper installation is for the taper to match the taper of the propshaft where it fits.
Then the prop, then the locking washer if it has one, then the nut.
Merc midrange engines with OEM props specify 55 ft-lbs of torque on the nut. Other engines may require a differrent torque settings as will specialty props with removable hubs.....seems they like it a lot tighter.....consult mfgr.
When installing the Merc prop, insure that the (nut) locking washer is installed such that the nut can go into the hex detent on the washer...tabs should be straight out when tightening. Usually takes 2 hands to complete this process as the washer gets hung up on the nut until the nut gets deep enough into it to cause it to spin with the nut.
A block of wood between the blade and anti-vent plate works well to hold the prop while tightening the nut.
Once the Merc nut is torqued, continue turning until one set (3 of 6) of tabs lines up with the slots in the back of the prop....tang them in place to lock the nut.....even though it has a nylon locking ring.
Some OEM's have a cotter pin to lock the nut so here you torque the nut and continue turning till the cotter hole lines up and pin it "with a stainless steel pin".
Spin the prop to insure clearance and uniformity of rotation. Should be no wobble or out of round movement.
HTH
Mark
