View Full Version : Line cutters and magnetic drain plugs

07-17-2013, 01:35 PM
I don't remember ever seeing anyone mention line cutters for their prop shaft seals so I wanted to mention it here. Apparently they are not considered stock equipment, but they are available for almost any lower unit including the older Volvo Pentas. Probably many boaters who do not fish don't really think about making sure they have them, but after talking to my mechanic friend they are a great and cheap form of protection from the fishing lines that can float. Just thought I would mention this and the importance of magnetic drain plugs in lower units since I discovered water in the lower unit of my 250EFI outboard on my Donzi 23' CC last week when doing some maintenance. It had no line cutter or magnetic drain plug.

Greg Guimond
07-17-2013, 09:13 PM
Smart and cheap. The magnet gives you DNA on your wear patterns and the "ears" save you heartache downstream. Spend a little time and sharpen the ears.

07-18-2013, 12:22 AM
Here are pictures of the Volvo Penta and the Mercruiser line cutters. The Volvo type rotates with the prop shaft, but the Mercruiser type is part of the seal which looks like the one in the center of the picture and is stationary in the housing. As the fishing line tries to wind inside the prop shaft seal it is cut by the stainless lip. I could not find a better picture of what the Mercruiser type looks like.
I should add that most of the Merc seals seem to be the regular seals that will not cut fishing lines.

08-05-2013, 03:34 PM
Followup to this thread. All four bolts that hold the impeller housing in place on the 250HP outboard lower unit broke off (I had to drill and retap with larger bolts) and the screw in ring that holds the prop shaft parts in place had to be drilled out and fractured to get to the shaft seals - all common from some salt water use before I got the boat. Sure enough, the prop shaft seals had been ruined from fishing line since the lower unit did not have a line cutter seal. The magnetic drain plug had to be ground down a little to fully seat in the drain as it was a little too long. Thankfully, the bearings and gears survived the water intrusion and the lower is now back together and installed back on the outboard.