Lower crank shaft seal replacement

[chris57]

"My 63 Johnson 10 H.P. (model QD24) is running excellent but is dripping unburnt fuel/oil mixture I believe out of a pin hole (vent) onto prop thus accumulating onto floor. I was concerned about it and have been since told that the lower crank shaft seal probably is the culprit. Due to cost of repair I have ordered Seloc manual and may plan to do this job myself. The motor has had lower unit serviced (seals & impeller) and tune up in August. Do you think lower crank shaft seal is causing this accumulation? If so, will Seloc manual step by step this fix? Please help, Thanks..."

[tom_barker]

I just went through this with a QD-23. I was told that it is caused by the condensation of unburned fuel in the exhaust housing. I had just rebuilt the motor and was only able to run it in a feed tank so it wasnt fine tuned. It was also suggested that part of the problem may have been the fact that I had it running in very cold water. After this was explained to me I stopped being concerned. I may be wrong about this but I think if your "lower crankshaft seal" were bad that you would have a vacuum leak and the motor wouldnt run at all. I am assuming that this is the seal on the powerhead that allows access to the crank shaft? tom

[joereeves]

"As Tom states, that has nothing to do with the lower crankshaft seal. His explanation about the unburnt fuel is right on."

[optsyeagle]

"I believe this is a normal condition and does not requre repair. This is what I was told about this conditon on my 75 9.9Hp Evinrude:

Black or Gray Oil Coming Out of Upper Exhaust Vent &/or Lower Unit Holes : Many of these motors are basically used as a secondary motor, & usually then as a trolling motor, and are ran for considerable length of time at a lower RPM. The fuel oil mixture ratio of 50-1 is probably too rich by some. The black oil that seeps out of the motor is just unburned oil from the gas mixture. The black color is coming from the carbon created during the pistons firing situation & is accumulated unburned inside the exhaust housing. The excess oil in the fuel is mixing & softening up the carbon, creating the black oozing oil. This oil seepage may not be evident until a day or week after usage, & then will seep out up to a couple of weeks later. It seems best for most boaters to then simply live with the idea that you may have to wipe it down after each usage."

[ken_denman]

"AND - make sure that the crud that accumulates in those weep holes does not plug the lower exhaust cavity. If you store your motor in sub-32, then any trapped water will expand and crack something."