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Author Topic:   1978 Johnson 9.9-HP Gear Case Seals

Smokeeta posted 04-13-2010 12:41 AM ET (US)
[I] have a 1978 [J]ohnson 9.9-HP. [I] replaced the lower unit seals about a week ago. [I] took the boat out for about two hours, and, when [I] brought it back, [I] checked the grease. It was just as milky as it was before [I] changed all my seals[.] [W]hat could [the contamination of the gear case lubricant] be [casused by][?] [Could the cause be a] bad set of seals? [W]hat do [I] do next[?]
Martino posted 04-13-2010 07:49 AM ET (US)
You need to pressure test the lower unit. You remove it, drain the oil, and pressurize it slightly using a pressure tester. Then you immerse it in water and look for bubbles. Every one I have ever had to reseal leaked at the same place, the driveshaft seal located under the waterpump.
seahorse posted 04-13-2010 08:09 AM ET (US)
Don't overlook the shift shaft O-ring as a source of leakage or the one under the shift pin screw.
Pressure and vacuum testing the gearcase will tell the whole story.
jimh posted 04-13-2010 09:00 AM ET (US)
The new seal kit may have contained a defective component, or, perhaps the installation was not done correctly.
Smokeeta posted 04-13-2010 12:09 PM ET (US)
[I] put [the outboard engine gear case] in a tank today[.] [I] had to work on the fuel pump[.] After [the outboard engine had] run about 10 [minutes] the [tank] had grease in the water[.]
contender posted 04-13-2010 09:48 PM ET (US)
You have four places the lower unit can leak from: the seal on the prop shaft, the shift shaft, and the two oil screws. Do you know what you are doing? Or was this the first time? Maybe did not [install the seal] correctly. I would check the seal on the shaft again. Where the O-ring goes you need to be sure the area is clean, clean. A small amount of dirt can push the seal out of round, thus causing a leak. I would first check [the integrity of the seal] under air pressure as Martino stated. I hate to say it, but another problem maybe could be a hair line crack some where on your lower unit. Good luck to you
dscew posted 04-13-2010 09:55 PM ET (US)
I think contender has some good points. I resealed a water pump housing on an old Evinrude 80 a while back, and as meticulous as I thought I was, water was coming in around the prop shaft seal. The seal was good, it was the shaft that was bad. Over time, sand and dirt, etc., had worn minute grooves in the shaft. The mechanic who figured it out said he shimmed the seal so that it ran on a different area of the shaft. That experience told me a lot about my level of experience.
jimh posted 04-14-2010 09:22 AM ET (US)
The appearance of grease in the water in the tank where you ran the outboard motor is a reasonably good indicator that the exhaust from the outboard contains some oil, however it is not the recommended method for testing the gear case for leaks. The recommended method for testing the gear case for a leak is to evacuate the lubricant from the gear case, then apply both a positive and then negative pressure to the gear case. With positive pressure you can immerse the gear case in clean clear water and observe for bubbles.
You should obtain the factory service manual for your engine, and then follow the illustrated procedure for replacing the seals and testing them. The procedures generally consist of many pages of steps and include many illustrations. It is not reasonable to expect that this information could be summarized and conveyed to you in a few sentences and without illustrations.
Tohsgib posted 04-14-2010 10:58 AM ET (US)
I have a nice 9.9 foot if you need one. Probably cheaper than a new seal kit: $75+shipping

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Author	Topic: 1978 Johnson 9.9-HP Gear Case Seals
Smokeeta	posted 04-13-2010 12:41 AM ET (US) [I] have a 1978 [J]ohnson 9.9-HP. [I] replaced the lower unit seals about a week ago. [I] took the boat out for about two hours, and, when [I] brought it back, [I] checked the grease. It was just as milky as it was before [I] changed all my seals[.] [W]hat could [the contamination of the gear case lubricant] be [casused by][?] [Could the cause be a] bad set of seals? [W]hat do [I] do next[?]
Martino	posted 04-13-2010 07:49 AM ET (US) You need to pressure test the lower unit. You remove it, drain the oil, and pressurize it slightly using a pressure tester. Then you immerse it in water and look for bubbles. Every one I have ever had to reseal leaked at the same place, the driveshaft seal located under the waterpump.
seahorse	posted 04-13-2010 08:09 AM ET (US) Don't overlook the shift shaft O-ring as a source of leakage or the one under the shift pin screw. Pressure and vacuum testing the gearcase will tell the whole story.
jimh	posted 04-13-2010 09:00 AM ET (US) The new seal kit may have contained a defective component, or, perhaps the installation was not done correctly.
Smokeeta	posted 04-13-2010 12:09 PM ET (US) [I] put [the outboard engine gear case] in a tank today[.] [I] had to work on the fuel pump[.] After [the outboard engine had] run about 10 [minutes] the [tank] had grease in the water[.]
contender	posted 04-13-2010 09:48 PM ET (US) You have four places the lower unit can leak from: the seal on the prop shaft, the shift shaft, and the two oil screws. Do you know what you are doing? Or was this the first time? Maybe did not [install the seal] correctly. I would check the seal on the shaft again. Where the O-ring goes you need to be sure the area is clean, clean. A small amount of dirt can push the seal out of round, thus causing a leak. I would first check [the integrity of the seal] under air pressure as Martino stated. I hate to say it, but another problem maybe could be a hair line crack some where on your lower unit. Good luck to you
dscew	posted 04-13-2010 09:55 PM ET (US) I think contender has some good points. I resealed a water pump housing on an old Evinrude 80 a while back, and as meticulous as I thought I was, water was coming in around the prop shaft seal. The seal was good, it was the shaft that was bad. Over time, sand and dirt, etc., had worn minute grooves in the shaft. The mechanic who figured it out said he shimmed the seal so that it ran on a different area of the shaft. That experience told me a lot about my level of experience.
jimh	posted 04-14-2010 09:22 AM ET (US) The appearance of grease in the water in the tank where you ran the outboard motor is a reasonably good indicator that the exhaust from the outboard contains some oil, however it is not the recommended method for testing the gear case for leaks. The recommended method for testing the gear case for a leak is to evacuate the lubricant from the gear case, then apply both a positive and then negative pressure to the gear case. With positive pressure you can immerse the gear case in clean clear water and observe for bubbles. You should obtain the factory service manual for your engine, and then follow the illustrated procedure for replacing the seals and testing them. The procedures generally consist of many pages of steps and include many illustrations. It is not reasonable to expect that this information could be summarized and conveyed to you in a few sentences and without illustrations.
Tohsgib	posted 04-14-2010 10:58 AM ET (US) I have a nice 9.9 foot if you need one. Probably cheaper than a new seal kit: $75+shipping