Confusion replacing my prop - part identification

[bluelinerdad]

Hi all, hope you can help with what I'm sure is a dumb question. Please excuse my ignorance.

I have a 1986 Bayliner Capri 185 with a Force 125 outboard. Due to my stupidity, I am in process of replacing my prop.

My old prop was a michigan, part number 072108, which according to the look-up on iboats, is a 19" prop. They didn't have any, so after reading through the forums and prop finder stuff, I selected a michigan prop, part # 072107, a 17" prop.

I took my old prop off, went to put the new one on, but something isn't fitting right. There was a plastic piece, conical shaped, that is between the prop & the washer & nut. When I put on the new prop, and I put this piece back on, it doesn't seem to tighten up all the way (it still spins even when the nut is fully tightened).

What is this piece? Do I need it? Just as a general rule, I hate having "extra" parts left over when I'm assembling something, makes me nervous. If anyone can help me identify this part, I'd appreciat it.

 

[Frank Acampora]

Re: Confusion replacing my prop - part identification

If the piece you are describing is a black, plastic , conical shaped piece, about 4 inches in diameter and 1 inch thick, it is called a "Flare Washer" or "Anti-cavitation Washer" Its purpose is to help prevent the prop from cavitating (maybe). I have another thread here with a long story about the development of that plastic piece.

However, I suspect that if you can not get it tight, when you removed the old prop, the thrust washer in the back came off with it. They tend to corrode in to the hub tightly. I also suspect that if you push hard on the new prop, it will rub on the gearcase so do not run the engine without the thrust washer.

So look at the old prop and the new one. If the thrust washer is stuck in the hub of the old one, drive it out with a screwdriver or good punch. Clean it well and coat it with anti-seize before sliding it back on the prop shaft and sliding the prop over it.

 

[bluelinerdad]

Re: Confusion replacing my prop - part identification

Thanks Frank, I appreciate the help. I didn't see the thrust washer,but I'll look again.