Lower Unit Issues.....Need Opinions\Ideas!

[Solomon_Man]

All,
I have a three 1950's (1956-1958) Johnson Outboards. The smallest is a 18HP the largest is 35HP. These were my dads originally and all have been winter projects. Used either on a 14ft 1980 SmokerCraft or 14ft 1959 Lonestar Monterey.

I have noticed a situation in all three lower units. They always have water in the lower units after running.
The 18HP does not seem to be as bad as the rest even though its run the most. Recently I have been working on the 30HP putting in a complete new ignition system/impellor/hoses/carb kit and finally new lower unit oil. Anyways, after running it in the test tank for 20 mins or so to try everything out I put it on my stand. This outboard motor is a backup. The next morning there was a good size puddle of oil/water foam mixture.

Anyways, I am in need of suggestions on how to deal with this consistent problem.

I have read that there is a washer that is used for the lower unit oil bolts. Are these one time use?...If so where is a good place to get replacements? Could this be some of the issue I am experiencing?

I have read that some people use Lubriplate 105 as a lower unit oil. Can someone chime in on its reliability and when to make this decision? Currently I change out the lower unit oil after every use. I am lucky to get on the water more then 5-8 times a year.

I am capable of rebuilding auto trans (manual and auto) but have not done much with lower units. They appear to be straightforward but from experience sometimes opening a old can a worms is not the best approach. Are Lower Unit seal kits readily available (Sierra/OEM)? Any good walkthroughs out there on the web/printed material?

Thanks for the help/opinions,
Chris

 

[Monte1961]

Re: Lower Unit Issues.....Need Opinions\Ideas!

In my humble opinon you will need to pressurize the LU in watertank with about 12 to 15 psi to see where the leak is really comming from. Fairly easy to do if you have access to compresser and tank. And to answer yer question on seals. There are to many to list.! best of luck to you.!

 

[Chris1956]

Re: Lower Unit Issues.....Need Opinions\Ideas!

Chris, All gearcases have seals where the driveshaft , propshaft and shiftshaft enter. In addition, all gearcases have drain and fill plugs. A lot of those old gearcases split down the center of the "bullet". If yours are like that get some seal kits and install them. The split design means it comes apart with a screwdriver (actually you will need to use an impact driver) Install gaskets on the drain and fill plugs. spagetti seals are used where the gearcase halves meet. Permatel #2 can assist with sealing as well.

 

[Solomon_Man]

Re: Lower Unit Issues.....Need Opinions\Ideas!

All,
Thanks for the responses!

All three are the bullet type. I should have mentioned I do have factory manuals for all of them but I also noticed they are available online as well. I did recently locate lower unit seals from Sierra. They are not $$$ ($17.06 each set\one set is $15.03). Is there any gotchas on replacing the seals? Will use the Permatel #2.

Monte1961 mentioned that you can pressurize the lower unit to find leaks. Do you just connect a hose to the oil fill hole and trim down the compressor pressure to 10-14 lbs and submerge in water /listen for leaks? Is this the procedure after resealing to verify its sealed?

Again thanks for the help!
Chris

 

[Chris1956]

Re: Lower Unit Issues.....Need Opinions\Ideas!

Chris, I would think that pressure test you described will work. When you disassemble the gearcases. Closely check for wear on the bearings. If the driveshaft or propshaft bearings have too much play, the seals will not work well, I would think.

 

[oldybutagoody]

Re: Lower Unit Issues.....Need Opinions\Ideas!

Soloman Man, You have three really great engines. THe best years for old OMC's OMHO. Do a search on iBoats for lower unit reseal and you'll find lots of info. Resealing one of these is not at all difficult. A little messy, but not hard. There's a seal at the prop shaft. A seal under the water pump impeller, an o-ring under a bushing for the shift rod, a spaghetti seal between the two halves of the case and a big o-ring around the prop head. Do some research and you'll be an expert in no time. The lower units on those old OMCs do leak after 60 years but a reseal is cheap and just takes a little time.. I've heard of using Lubriplate 105 but I wouldn't except as a last resort. Sometimes, even after resealing, they still leak (albeit less) because of wear around the drive shaft or the prop shaft in the seal area and if so, the Lubriplate 105 can salvage an otherwise good engine but try the reseal first. You'll need to make a tool to drive out the bushing to get at the shift shaft o-ring but it's just a 5/16" steel rod ground with a taper down to 1/4". A seal puller ($12 at harbor Fright) helps too. MarineEngines.com has seal kits. I think iBoats does too.

 

[Solomon_Man]

Re: Lower Unit Issues.....Need Opinions\Ideas!

Thanks Everyone!

I will pull the backup outboard and do the seal swap first and then once I know the lay of the land will move on to the in use outboards.

Thanks,
Chris

 

[HighTrim]

Re: Lower Unit Issues.....Need Opinions\Ideas!

Forget pressure testing it to determine where the leak is. Just reseal the whole thing while you have it apart. You'll thank me later

I personally swear by 3M 847 as the sealant of choice when doing a gearcase. Have done ALOT and can say that stuff works great.

The prop shaft seal housings are fragile, take care when removing the prop shaft seal. Ask me how I know

Ensure all the mating surfaces of the seal housing are clean, use Acetone to get good adhesion with the sealant. If you need the tool to remove the shift rod seal, F_R on this forum sells them, PM him. The hardest part is cleaning everything once it is all apart, getting all the old sealant off. Rebuilding it is the easy part.

 

[oldybutagoody]

Re: Lower Unit Issues.....Need Opinions\Ideas!

I second everything Chris told you. He helped me out bigtime. The 3M-847 is magic but boy is it tacky. It's hard to find though. I ordered a tube for $13.37 plus 5 bucks shipping from Jamestown Distributers. It was a big tube about the size of a toothpast tube and it'll probably last me a lifetime. Good stuff though. Worth every penny. One 5oz tube will be PLENTY for all 3 or your motors and you'll have enough left for 30 more.

Forget pressure testing it to determine where the leak is. Just reseal the whole thing while you have it apart. You'll thank me later

I personally swear by 3M 847 as the sealant of choice when doing a gearcase. Have done ALOT and can say that stuff works great.
The prop shaft seal housings are fragile, take care when removing the prop shaft seal. Ask me how I know

Ensure all the mating surfaces of the seal housing are clean, use Acetone to get good adhesion with the sealant. If you need the tool to remove the shift rod seal, F_R on this forum sells them, PM him. The hardest part is cleaning everything once it is all apart, getting all the old sealant off. Rebuilding it is the easy part.

 

[Solomon_Man]

Re: Lower Unit Issues.....Need Opinions\Ideas!

Thanks for the help!
Chris

 

[Willyclay]

Re: Lower Unit Issues.....Need Opinions\Ideas!

I have noticed a situation in all three lower units. They always have water in the lower units after running. ...The next morning there was a good size puddle of oil/water foam mixture. Thanks for the help/opinions,Chris

I always hate it when I am the only one thinking a certain way BUT your description did not shout "water in the lower units" to me! The foamy puddle is what I would expect to see after running a motor from that era due to the unburned fuel/oil mixture draining out of the exhaust. BTDT. Unless you have drained the gearcases AND found water in the gear lube, then you might want to hold off on tearing into all three lower units. See my signature as I make no claims on being an expert. Good luck!

 

[HighTrim]

Re: Lower Unit Issues.....Need Opinions\Ideas!

"They always have water in the lower units after running."

I dunno, sounds like water in the lower unit to me Maybe need your spectacles Old Geezer, lol (kidding)

 

[Willyclay]

Re: Lower Unit Issues.....Need Opinions\Ideas!

Currently I change out the lower unit oil after every use.

Everybody but me in thread is probably right on target but I just did not want to see him crack open all three LU's if it was not absolutely necessary. I remember the first time I found "the foamy puddle" after running one of these great old motors and I was not happy. Then I talked with an experienced outboard guy who explained what was normal and what was not!

 

[Solomon_Man]

Re: Lower Unit Issues.....Need Opinions\Ideas!

All,
Like to clarify....Keep in mind different outboards here....

The outboard oil is very similar to oil found in a car that had a bad cylinder head....grayish white....and if I let it sit a day or so the water/oil will seperate and you can clearly see the oil and water. The 18HP unit may or may not show this based on the length of time I run it. All day It will have a small amount. My plan on this outboard it to pick a seal kit up and have it in my stock just in case it starts to get worse....also it appears this one will take a extra week to get as its out of stock at both Iboats and Marine Engine so it may be in my best interest to get it now.

In the latest outboard (30HP) that I did the tune-up/cleanup it left a considerable puddle of gray oil water mixture. Which after leaving in a drainage pan seperated into oil and water. Also the 35 HP motor, I noticed it has the grayish water oil mixture after every use. So these two will be my main candidates for correcting. I have a Big Twin (25HP) that I am also converting to electric Start and a tiller setup which I may just buy the seal kit to have it type of thing as well.

My thought on this situation is basically if this is something a person who has a little more experience then the back yard mechanic can fix (I have automotive college level classes under my belt and my dad was a GM mechanic but I ended up as a engineer) then I would just replace or have them all cause the cost is really reasonable.

Does anyone know if any major chain stores carry the 3M-847 sealant?.....Having trouble finding it on MarineEngine or IBoats...Or will I be stuck buying it online somewhere else.


Again thanks for all the help,
Chris