Why does grease leak between the prop and the foot on my 1977 Johnson 75 Stinger Outboard?

Question

I just bought a 1977 Johnson Stinger 75HP from a guy and it has set for about 3 years outdoors on an old boat. It starts and runs fine. The forward and reverse works fine. I put the waterhose on it in the yard and it just leaks grease. Is there a seal if I take the prop off that would need replaced or what? Thanks

Answer 1

This engine's exhaust is dumped into the gear housing and comes out the center of the prop hub.  If this motor was winterized, and had a lot of oil in the fuel (it should have 50:1 TWC oil mixed with the fuel) then it will come out of the drive at the prop.  It will be black!     If you are in  fact leaking lower unit oil, it will be honey colored.  If that is the case, look just above the cavitatiln plate on the starbard side. there is a large vent plug s***w. Take it out and use a wire tie, and use it like a dip stick.  See how far down the oil level is.  If it's not, white but amber, I don't think the gearcase is leaking. If the oil is white it is.  The Prop seals don't often fail first, it's the drive shaft seal that fails first.  If this is the problem, I'd recommend you take it to a dealer for service.   Good luck!!

Answer 2

There's no reason you can't do all the maintenance on this motor yourself but you'll need a good manual.  get the original factory service manual at http://iboats.com or http://marineengine.com

starboard side of the lower unit you'll see two s***w plugs, they'll be obvious because they fit a very large slotted screwdriver.   The lower one is the gearcase drain and the upper is the gearcase vent.

Remove the drain first then the vent.  Let some of the oil drain through your fingers, look for bits of metal.  Small amount of shavings on the drain plug magnet is normal.  A lot of metal or larger shards indicates a problem.

If the oil has a milky or streaky appearance, it means water is getting in and you need to re-seal the lower unit.  Not something you want to attempt with the manual.  Three seals -- propshaft, driveshaft and shift rod.  You have to pull the bearing carrier out with a gear puller to change propshaft seals.

If there's no water in the oil, then what you're seeing is just unburned engine oil dripping through the exhaust.  Normal in a motor that's sat unused for a long time, or been used a lot for trolling.

Refill the gearcase from the drain plug -- for $10 get a plastic pump that screws into the drain, pump the oil in till it starts coming out the vent.  s***w the vent plug in, then the drain plug.  It'll hold about 24 oz. of oil - use only marine gearcase lubricant.

Change the gear oil annually -- I do mine before the first hard freeze, so in case of water intrusion it won't crack open the gearcase.

How it runs on the muffs, without backpressure on the underwater exhaust, is no indication of how it will perform once you put a load on it in the water.

As gasoline evaporates it leaves behind a varnish that can clog your carburetor jets.  Don't be surprised if it bogs down when you go to full throttle.  If it were mine, I'd rebuild the carbs just as preventive maintenance.  It's really easy -- you have 3 fixed jets per carb, so there's no adjustments.  You'll need 3 kits (about $12 apiece from iboats) -- there's an instruction sheet in the kit.

Replace the waterpump impeller -- after 3 years it'll take on a "set" and be less effective.  Worse, it might've started to dry rot -- you don't want bits of impeller clogging up your water jacket.  Do this every couple or 3 years.

This motor will run best with Champion QL77JC4 gapped at .030

if you are a do-it-yourselfer, check this out:

http://forums.iboats.com/forumdisplay.ph...