replacing prop

[Merc90HPnewbie]

Ok here I go again with my beginner questions. I spun out the hub on my old prop but luckliy the boat came with a spare new prop. The splines on the new prop were kind of corroded (the prop was stored on the boat) and I used a brass brush to get the green powdery stuff off. I was going to smear a bit of the waterproof grease (Trailer axle bearing grease) in the prop when I read the container which said "do not mix greases of different soap types". Not knowing what was on the old prop and shaft I sprayed it down with brake parts cleaner and got the old grease off. Then I relubed the driveshaft and new prop with the waterproof grease and reassembled. When I had the old prop off I noticed a very fat washer behind it. Behind that was a hollow area with a zerk fitting.<br />So my question is, what does this fitting lubricate? And how often should I lubricate it? Also with the warning about not mixing different greases how do I make sure all the old stuff is out (of wherever it is this fitting goes to) before putting in new grease? Or do I not worry about that? How do I know when I've filled it to capacity?<br /><br />Thanks!<br />oh PS it's an 85 Mercury straight 6 cyl 90 horse

 

[Skinsk]

Re: replacing prop

I think in this particular application, it's ok to mix grease types. The grease is on the prop shaft primarily to keep the prop from seizing onto the shaft (at which point it has to be burned off the prop shaft). <br /><br />That big washer is the prop thrust washer, make sure you have one on before installing the prop. If you forget it, the prop will try to migrate forward, eating its way through your gearcase.<br /><br />That zirk fitting is there to lubricate the surfaces of your bearing carrier. There should be two, one where you saw, and another deep inside the hole you were looking in. Merc doesn't put them on gearcases anymore. I think it was an attempt to keep salt water gear cases from corroding together, making removal of the bearing carrier difficult during rebuilds. You can try and shoot grease in there if you'd like.<br /><br />Scott..

 

[Merc90HPnewbie]

Re: replacing prop

Thanks skinsk! Do I have to lubricate the thrust washer? Does it rotate with the prop and prop shaft or stay stationary against the lower housing?

 

[Skinsk]

Re: replacing prop

I like to put some grease on the propshaft taper, where the thrust washer rides. It spins with the prop, and transfers all the prop thrust to the prop shaft.<br /><br />Scott..

 

[Wellcraft 89]

Re: replacing prop

Make sure you put that thrust washer facing the correct way, it has a taper in the hole on one side if you didn't see it and put it in wrong can ruin the prop shaft.<br /><br />Rich

 

[Spidybot]

Re: replacing prop

Agreed. The DO NOT MIX warning is general. Not knowing the reactions of every possible grease mix, they say DO NOT.<br /><br />Worst case it would form a glue-like substance.<br /><br />Good idea to apply marine grease to all parts and very important to fit (right way) the washer.<br /><br />BTW: When servicing and maintaining your motor, a maual would come handy and prove it's value many times.<br /><br />Link on bottom of this page.