Gear Oil leaking from water intake Johnson 15hp

[Lennyd123]

Hi all,

Just picked up a used 14' with a 78 15hp Johnson manual start that actually runs better than expected (seller said "it starts but won't stay running "), but has a few issues including gear oil seeping out the raw water intake.

Note that the lower unit was drained, had some water in it plus some of the dirtiest gear oil, but it was changed with quicksilver lower unit oil, and the oil stains that were wiped off came back with the new lube, but it is easier to determine it is gear oil since its no longer black.

I will be checking the lower unit oil level and any water contamination after running it tomorrow or day after, but was looking for any ideas on where to consider digging into as I doubt the problem fixed itself.

I did not see any signs of oil around the prop seal (would expect to if seal was bad even though it was water in the lower end), and I have also noticed that the water drains out of the front near the bottom of the main swivel to turn the motor and not sure if there may be a connection.

Since cooling water flow seems less than optimal even though there is a steady wealth stream from pee hole I will likely be dropping the lower to do a water pump kit so any advice on what to look for while it is apart is appreciated.

Thanks in advance for any suggestions

 

[Vic.S]

If you are sure it is gear oil , not unburnt oil from the fuel, then,the driveshaft seals below the water pump are leaking.

Relatively simple job to replace them while the lower unit is off to do the pump . Note the correct orientation of the seals.

Probably worthwhile renewing the shift rod seal ( O ring ) at the same time

If you can pressure / vacuum test the unit do so

 

[Lennyd123]

Thanks for the quick reply.

Yes definitely was gear oil (can't mistake the smell, and color when fresh), but did not see it when running, and when was just vertical both before and after swapping out the oil.

So I am sure the drive shaft seal id below the water pump, and not normally part of the pump kit?

Is the shift rod o-ring mounted in the lower unit?

If it is do you have any idea what may be going on with the water draining below the pivot point (just below the grease zerk)?

I am assuming there is a port for this like the larger outboards I had in the past.

Far as a pressure or vac test I will see what happens as I would need to pick something up (still unpacking from a recent move, and not sure of which of the boxes the tester may be in lol), but the water got in the drive from someplace, and unless the seal below the pump looks bad I agree with your thoughts on testing.

Would vac testing need to be done with the drive dry?

 

[Lennyd123]

Wasn't able to get back until after dark, will advise what I find when can see what I am looking at lol

 

[kbait]

If you find water/milky lube in gearcase, drain it out, pull gearcase off, pull waterpump/wear plate, and pressurize gearcase through one drain hole with plug installed in other hole. Won’t need much pressure, and spray soapy water around propshaft seal, driveshaft seal and shiftshaft bushing. You will find the leak in one of those locations, unless the gearcase is cracked, or leak is at he propshaft bearing carrier o-ring (rare). I commonly replace the offending seal and re-test.
Good luck!

 

[Lennyd123]

Thanks for the input.

It appears I won't be able to pull the boat and motor until Sunday, and will see what I find, and post the results.

I will also likely try pressurizing over vacuum since I had no luck finding vacuum gauge tool.

Will post back soon.

 

[Lennyd123]

Been short on time (as always lol) but did pull her, swapped out drive oil, and it was clean minus a small amount of metallic discoloration that was likely left over and flushed out etc.

No idea why there was no signs of water intrusion (it was run for over 4 hours on last lube change), but will be attending to pulling the lower to inspect and pressure test soon.

On the positive side I was able to ID a separate problem as it runs well, but after getting the revs up sometimes stalls, and found the carb leaking fuel, and what appears to be a stuck float needle so a carb kit is on order as well.

One quick question is if it is a better idea to pre order the lower unit seal kit, or wait until its tested and just pick up the seals needed?

I know it's a lot less expensive to just match up the parts needed, and so much is just coming from China now anyhow it is a tough choice to pay almost $50 for $15 in radial lip seals.

 

[Geoffrey Graydon]

Well,the shift rod seal is just an "O"ring and the skeg seals are the washers on the drain and overflow oil plugs,and the spaghetti seal for the skeg itself.They should all be available at your local marine dealer ,other wise right here at Iboats. Incidentally,
I have in an emergency used window screen spline for the skeg seal with very satisfactory results.

 

[Lennyd123]

"I have in an emergency used window screen spline for the skeg seal with very satisfactory results."

That's very interesting.

Since there wasn't any water in the gear oil, and the carb kit already arrived I will be messing with the carb first, and inspect the gear oil again after a little use, and go from there.

I suspect there must be a small leak somewhere or there wouldn't have been water in there in the first place, but I have even less information of prior history than the time to actually wrench it and have to spread it out over time etc.

 

[jimmbo]

A 78 15hp Doesn't use a Spaghetti Seal, the gear housing is one piece, the Skeg is part of the casting

 

[Lennyd123]

Thanks Jimmbo, good info.

Sadly have not had time to put her back in the water to see how the carb rebuild went, or start putting time on it to see if has any more water getting into the gear case.

Oddly the carb went without a glitch (almost too easy), there was minimal rust or putting in the bowl, it did have a bunch of "gunk" in the bowl when first opened, and appeared clean otherwise, but the part number didn't match the parts list for 1978 or 4 years up and older.

The throat is definitely larger at the intake end, but I have been told this is not a deciding factor.

Number on the carb is 0388275, and had a fast jet #56

Can anyone confirm if that is a 15 carb, and what year it may be?

 

[oldboat1]

Post a clear picture looking straight into the carb throat from the front. The number you see is probably a casting part number for the bowl or whatever. 56 is the right jet.

 

[Lennyd123]

I cant explain why but the pics I took of the throat are just black. The rest are fine though lol.

I also meant to measure it, but couldn't find my calipers (still cant).

It's back together now too.

 

[Lennyd123]

Wanted to give you guys an update as you have all been helpful.

Thankfully the motor ran great with the new carb rebuild, and I was able to run it on plane at wot without any bogging or stalling like had happened prior.

All was good except the fuel line from the pump to the carb which I couldn't find loc to replace, and was leaking because the previous owner used a hose that was too large, but did manage to get a small SS clamp on it to stop the steady flow of gas at the mounting point. Any suggestions on what this hose should be would be appreciated.

Also it had a steady light flow of water out the pee hole, but though there was a steady stream out the exhaust the flow of thence hole actually was less at higher rpm.

I will be hauling it again soon as won't be using it during the passing of hurricane Dorian, and will check this out as well as the gear oil and see what I find.

 

[Lennyd123]

Also no signs of fear oil at the cooling water intake, and put about 3 to 4 hours on it at varying speeds so maybe that was a fluke somehow.

 

[kbait]

Fuel line from pump to carb is 5/32”.

 

[Lennyd123]

Thanks is to all for your help.

Everything stayed good after many additional times out, and I am thinking it should stay that way.