Pontoon Boat & Deck Boat Forum

Just got a new prop from Turning Point, and it came with a "lab ring seal". It wasn't listed when I ordered the propeller, and I'm not sure if I need it on my motor. Here are the instructions that came with it:
20150724_170918 by Casey Paulson, on Flickr

I have a 2001 Mercury 2 stroke 90hp. From what I see listed, it looks like ALL Mercurys that have the 15 spline shaft should use it, right? I tried calling Turning Point but they had closed their offices for the weekend when I called. Neither of the 2 props we had used before had this part, so I wasn't sure when I saw it, and I can't find any info online.

Thanks.

The prop looks to be made to fit all midsize cases and that special ring is designed to tighten the tolerances on "slightly bigger" midsize gear cases. If that gap is too big an excess amount of exhaust gas can get out and cause cavitation/aeration issues. 13 spline Johnson/Evinrude/Etec V4 and older Johnson/Suzuki 60-70hp 13 spline 4 strokes had a slightly smaller diameter on the case which causes a problem for "Universal" fit midsize prop. Most manufactures don't bother with the "ring" though as its usually is only need if you actually have an issue which is rare. On my Johnsuzki 70 I've had to file that area a bit to get Mercury brand props to fit my engine, but the Quicksilver version of the same prop slides right into place because its machined down slightly more from the factory to fit all midsize/V4 cases.