Need assistance on 98 Johnson 50HP leaking...

[tigerbalm2424]

My 98 johnson started leaking black sludge(assuming lower unit oil) out from the bottom of where the prop enters into the lower unit. This happened after I started it up yesterday and ran it for about 5 minutes. First start of the year after storage. Never had a leak before. Just bought it last summer.

Does anyone have a how-to on replacing all the seals in the lower unit on this 50HP johnsons?

I have removed 52, 62, 51, and 59. How do I remove the 2 oil seals (61)?

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[Valv]

You'll find out the Seloc or Clymer manuals are not very informative when doing work above basic skill level.

Take it to a shop and have it done, otherwise get a OEM shop manual.

[tigerbalm2424]

 Originally Posted By: Valv

You'll find out the Seloc or Clymer manuals are not very informative when doing work above basic skill level.

Take it to a shop and have it done, otherwise get a OEM shop manual.

OK, i will have someone look at it.

So, has anyone on this site ever replaced these two shaft seals on any motor?

[Minnesota Fats]

Wait, before you tear into seals, make sure it isn't fogging oil/two cycle oil coming out of your thru hub exhaust port. This is extremely common for the first start of the year. Black sludge doesn't sound like gear oil to me. Gear oil is thick and clear to light brown. If you want to compare, drain a little gear oil to see if you are dealing with the same substance.

[tigerbalm2424]

 Originally Posted By: Minnesota Fats

Wait, before you tear into seals, make sure it isn't fogging oil/two cycle oil coming out of your thru hub exhaust port. This is extremely common for the first start of the year. Black sludge doesn't sound like gear oil to me. Gear oil is thick and clear to light brown. If you want to compare, drain a little gear oil to see if you are dealing with the same substance.

Ok, so I have heard some say to do a leak pressure test. Is this easy to do? I will drain the LU oil. I have a compressor but what fitting would I need on the fill screw hole to attach it and apply pressure?

[Minnesota Fats]

You don't need to do a pressure test until you verify that the substance is actually gear oil. If it is, you can get the proper fitting from most hardware stores that carry threaded fittings - just bring in your drain plug and match threads.

I'd bet you don't have an oil leak, you are just clearing out the fogging oil from the motor.

[tigerbalm2424]

 Originally Posted By: Minnesota Fats

You don't need to do a pressure test until you verify that the substance is actually gear oil. If it is, you can get the proper fitting from most hardware stores that carry threaded fittings - just bring in your drain plug and match threads.

I'd bet you don't have an oil leak, you are just clearing out the fogging oil from the motor.

Ok, i will hook up the muffs and run it again to see if it leaks. I soaked up all the black sludge that was in the lower unit housing that I could see, so if any more shows up and looks like LU oil I know i have a leak.

THanks all.

[marine_man]

I would monitor the situation - it very likely is unburnt fuel & exhaust coming out.

When you changed lower unit oil before you stored it was there any water in the oil?

I would monitor your lower unit oil level (stick a tie wrap end in the top hole and keep tabs on the level) and see if you're loosing any before I'd attempt a seal job.

In regard to leak checking it - dealers will have a pump & gauge, much like a radiator leak checker) that they can pressurize the lower unit and see if it leaks over time.

Good luck!

marine_man

[john.wells]

I would like to add for anyone looking here, NEVER use a compressor to do a pressure check! It will blow the seals out and you WILL have several leaks at that point. Have a pro do it.

[eurolarva]

I would guess unburned gas and fogging oil. Take a whiff of the black sludge. Nothing in the world stinks worse then lower unit gear oil. If it smells like gas dont worry unless you keep seeing it in the water when you fish. If the gas keeps leaking it could be a puddle valve or a cylinder not firing completely. Being it is this time of year and you did fog it last fall that is probably all it is. Most common leak spot is where the bearing carrier connects and that seal goes because fishing line gets wrapped around it and damages the seal.

If you pressure test use a basketball pump and dont fill more then a couple lbs per inch.

[tigerbalm2424]

You guys were all right. It was unburned gas and foggin oil.

[Valv]

 Originally Posted By: john.wells

I would like to add for anyone looking here, NEVER use a compressor to do a pressure check! It will blow the seals out and you WILL have several leaks at that point. Have a pro do it.

Yes, as John said DO NOT use a compressor !!!

[mroyten]

Got the same situation with my engine. Thanks guys for all the helpful posts.

Matt