leaking lower unit, 1963 Gale Sea King (OMC) 15hp

[KonradS]

I am new to this forum, so hello. I am truly and most sincerely stumped. I have a 1963 Gale Sea King 15hp. I have completely disassembled the lower unit cleaned and re-assembled with all new Sierra seals. The original driveshaft seal was a single seal; the replacement is two seals that I installed back to back so that the first seal will act with respect to pressure in the gearbox and the second seal will act with respect to pressure from the water pump. There is very little wear to the components; the drive shaft has very slight wear where it contacted the old seal. More of a shiny spot, really. before replacing the seals the lower unit was leaking badly, and the seals were completely shot. When I ran the motor after replacing all the seals, still got the big ol' oil slick. I removed the lower unit and drained the oil. there was a small amount of water in the oil, and a lot of oil in the manifold around the water pump, dripping out the weep holes as would be expected from a leaking lower unit. Here's the kicker: when I pressure test the lower unit, I find no leaks, including when turning the driveshaft by hand and when shifting and wiggling the shift rod. I also looked for leaks in the casting of the lower unit. I don't have a pressure gauge on my home made pressure tester, but when I check for air pressure after several hours, it is still pressurized. No air flows in from compressor with regulator set to 10 psi when I try to put more air in. And yet, when I ran the motor it was like a mini Exxon Valdez. If anyone has ideas or suggestions it would be most appreciated.

 

[racerone]

Did you replace shift rod o-ring ?-----And those motors will leave an oil slick which is the oil mixed with gas.

 

[KonradS]

Hi, Thanks. Yup, replaced the shift o-ring. The oil was definitely gloppy gear oil, and lots of it. The only other observation I have that I left out is that it seemed to be leaking more after the engine was hot. May be that it simply took a while for me to notice the oil as it accumulated in the barrel. I have worked on a lot of different sorts of motors over the years and feel pretty good about my experience, but either I am missing something or there is something weird going on that I don't understand. I have the factory manual, got the complete seal kit and water pump kit and used the good 3M super gooey sealant on the spaghetti gasket etc. And it holds air! sheesh!...

 

[racerone]

It would be the oil that you mix with the gas !

 

[KonradS]

Just looked at my last post- The sheesh at the end wasn't a response to your post! I appreciate all thoughts. It was my frustration that the unit holds air but something is still leaking, poorly stated. Apologies. I may be dating myself, but I first used 2 cycle outboards in the early 70's when I was a kid- the smell of burning 2 cycle oil, creosote soaked pilings with sheet lead protecting the top and ships burning bunker oil are the smells of my youth! The oil that is leaking is gear oil rather than a slick of un-burnt 2 cycle oil. Thick globs of it covering the water pump housing...

 

[racerone]

Good luck with it.

 

[KonradS]

Thanks! Whatever is going on is not magic; when I figure out what it is I'll post it in hopes it will be useful to someone.

 

[Crosbyman]

try vacum testing also .. gc should pass both pressure and vacum tests

if it holds pressure do you actually see water in the gearcase when you drop the oil .????.. if not bucket oil is just exhausted fuel oil mix recirculated in the water pump...

run it on the lake and back in the shop drop the GC oil to see if water ingress took place.

 

[KonradS]

Thanks for the tip. Pressure testing is all over the forums, but this is the first I've heard about vac testing. I'll give it a try and let you know what happened

 

[KonradS]

Okay- here's the report- took a minute because I had to turn an adapter for the 3/8 machine thread on the lower unit to 1/8-27 npt to connect the vacuum pump... I was able to produce a small leak wiggling the shift rod. removing the bushing and o-ring for the shift rod I confirmed something I noticed earlier. there is a slight reduction in the size of the hole preventing the bushing from being over driven against the o-ring. However, when the bushing is fully seated, there is a space almost double the thickness of the o-ring so that the o-ring can slide up and down in it's seat. Is this normal? having had to make a bit of a study of the correct sizing of o-ring grooves in the past, this seems odd to me. I am considering putting in double o-rings. with all the oil in the manifold and water pump, it seems pretty clear the leak is either at the shift rod or the driveshaft, and the shift rod seems more suspect to me. Any thoughts?

 

[saltchuckmatt]

What vacuum pressure did you put on it and how long did it last? Did you check for water in the gearcase? Water goes in more than oil ever comes out.

Still very well could be 2 stroke oil, water and unburnt gas....that concoction makes some awful goopy stuff.

Those older motors require a pretty rich mix, what's your fuel to oil mix ratio?

You might be beating a dead dog.

 

[Crosbyman]

how about some pictures so we can all see this oil... in the water pump . the bucket etc...

do you or not have water in the GC after a successful run after good pressure and vacum test results ?

 

[KonradS]

Unfortunately, I didn't take photos as I went, and the lower unit is torn down again. At this I think I may be looking at a combination of things-
*compression 80 in upper cyl, 85 in lower, so not great.- lot of carbon on pistons, etc.
* gear case held 15psi, was able to create small leak at shift rod at 27 in. Hg vac after all new seals
*small amount of water in gear case after a test run
* after feedback from y'all, thinking maybe a combination of gear oil & un-burned fuel/oil mix in the manifold.
I'm going to try de-carbonizer to see if that gets compression up to 100 psi or so, if not do the rings. As I mentioned earlier, there is space for two o-rings on the shift rod, so even though unorthadox, I think I'll put two o-rings on shift rod, as a single o-ring can move around, and that appears to be the location of the gear case leak. Also timing is set by just gapping points- I'm getting a timing tool to dial in the timing better. Then, well see what all that does! I appreciate the help & suggestions!

 

[saltchuckmatt]

They are fun motors.

 

[Crosbyman]

up to you.... why not run it with a good dose of engine cleaner. Some like seafoam some don't. if it runs decently I would not crack it open. fix the oil leak is the first goal.

if you can't find the oil leak add a UV dye in the GC oil & it will show up clearly .

the engine are look a like with OMC timing can be set on the high spot of the cam or with a VOM ... no need for a fancy tool but I agree they work nice

 

[KonradS]

definitely a fan of seafoam, when it works! Much rather be fishing than tearing down a motor... The old 1963 Montgomery ward Sea King looks good on my 1963 Sears boat! Thanks for the timing video. Hadn't seen that- I'll save my 50 bucks for the timing tool and go that route! My motor is a 1963 15 hp Montgomery Ward Sea King made by Gale- subsidiary of OMC, so motor is OMC in every way- parts are all OMC. It's nearly identical to the motor in the timing video. If I still have a leak after Sea Foam, timing and reassembling the lower unit I'll try the UV dye- but maybe lady luck will smile upon me!

 

[racerone]

The bearings on the crankshaft may not be the same as an OMC 18 HP.

 

[airshot]

They are fun motors.

You must be expecting some really high water with that motor so far up the wall !! Lol...

 

[KonradS]

Well, after a day in the barn,I think there is a reasonably happy ending! Thank you all for the suggestions. I bought the motor last fall, ran it once and realized I had some work to do. I think I was flummoxed because there were multiple issues... all the seals were original and completely shot, including the upper and dreaded lower crankshaft seals, which I knew. Lower unit leaked like a sieve and it turns out the the mixture was really rich to overcome the blown lower crank seal and the timing was way late so it was dumping lots of un-burned fuel-oil mix. Total oil slick. So you guys that mentioned that were right on. The motor had probably been running badly for a while and the carbon build up was horrendous. I set the points/timing after looking at the vid Crosbyman put up above, put the lower unit back together pressure and vac tested it, put it in the barrel and fired it up. When I gave it the sea foam treatment it was like the end of the world! thought the neighbors would call the fire department! And it made some pretty thick stew in the barrel. And, given I am in Vermont, I got to do it in a snow squall! rinsed it out and leaned up the the fuel mix a bit and its running pretty good. didn't get the boost in compression I was hoping for after the sea foam, but if it runs okay and doesn't make a mess, I'll leave it for now. Maybe next winter I'll do the rings and anything else wanting inside. Thank you all again.

 

[Crosbyman]

thanks for the feedback.... if it works don't fix it any further