Water in LU....again

[Peach1303]

1B506554
2008 Mercury Pro XS 225
Does anyone else have these issues of water constantly getting into the LU? Just checked it, found milky oil again. This is the third time in two years. Last time I brought it in, the mechanic said it was the prop shaft seal leaking at higher pressures doing the pressure test. Is there another spot that it could be failing at again? It’s quite irritating when I only put on average 10-15 hours per year on the motor. Have to bring it back to the mechanic for an injector wire issue, anything I should ask him to check with the LU when I bring it in?

[OldTimer57]

Two seals on top, one around the shift shaft, one around the drive shaft. Either can leak, although for me, the shift shaft has been the one that leaked first, between the two. The prop shaft seal is more exposed and suffers when fishing line gets wrapped around the prop shaft.

Should check the obvious first with a pressure test. Verify no prop shaft runout. First find what is leaking, then fix it. I personally replace all of those seals if I replace any of them. Done correctly, leaks won't happen (assuming you don't have a hidden crack in your gear case, which is not very common.)

[Peach1303]

Just received a call from the mechanic. He stated it’s possible something broke off from a diverter and is causing the prop shaft seals to wear out. He said he remembered reading about it a while back, and it would be a very long and costly job to fix it. Does this sound right? Causing the prop shaft seal to wear out? He is pressure testing it right now to see, and is resealing it all, but I just want to be prepared for a bad news phone call.

[Savage]

I have no idea what he is talking about....."diverter is causing prop shaft seals to wear out"

[Peach1303]

He made it sound as if it was possible a piece broke off inside the engine and could’ve been burning out the prop shaft seals, which would require the power head needed to be taken off, turning it into a massive job. My hope at this point is just bad seals, and worst case scenario being a bad prop shaft. Sorry I can’t be more clear as I was confused about the diverter as well. I’m hoping to find out more tomorrow.

[Savage]

"Wearing out" and "burning out" (overheated, melting) are two totally different scenarios. I know what he's talking about now. If the seals are melting due to temperature, then yes the powerhead needs pulled to check the strainer.

[JOE54]

well it aint bad seals ,and dout its propshaft, could be poppet valve, you got a hyd jack plate ????? watch that water psi super heated exhaust will burn up p/s seals =engine too high

[Peach1303]

No, it’s not a hydraulic jack plate. I get about 20 psi at WOT

[haus9393]

I had my seals done around 540 hours. 2 months later and 100 hours I changed the oil again to find it was full of water. The thing was still running perfectly fine. Since it was under factory warranty I ended up getting a brand new lower unit no questions asked. So to answer your question yes they can keep leaking over and over. Might be the lower unit. Might be the tech doing the work. Either way I’m extremely pleased how my situation ended up because mine was a ticking time bomb. Can only imagine how those bearings are doing after being lubed with water for hours on end.

[EuropeanAM]

Could also be the person filling the gearcase. OVER-FILLING the gearcase can result in venting, seal failure, or water in lube.