1956 15 HP johnson fuel leak where powerhead meets the lower unit

[budsbait]

I have a 1956 15 hp johnson that I recently bought on Craigslist. It sat for many years.

It is running well now after replacing coils but has a pretty bad fuel oil leak where the powerhead meets the lower unit. It is on the front of the motor the shifter side. When going full throttle not much of a leak but when going slow it sprays out. I guess this is actually the bottom of the crankcase. Could the lower crankshaft seal be causing this problem? I plan on replacing the seal but while apart I'd like to be sure and find the leak.

I've been checking for the gasket where the powerhead meets the lower unit and can't find it anywhere what is the best replacement. Should I make my own?

I hope it isn't in the crankcase I'd rather avoid taking it apart. Any ideas, Thanks

 

[Daviet]

Re: 1956 15 HP johnson fuel leak where powerhead meets the lower unit

I wonder if the base gasket for the power head is blown, select your model number and find the base gasket you need.

1956 Johnson Evinrude 15 hp Outboard Parts by Model Number

 

[budsbait]

Re: 1956 15 HP johnson fuel leak where powerhead meets the lower unit

I wonder if the base gasket for the power head is blown, select your model number and find the base gasket you need.

1956 Johnson Evinrude 15 hp Outboard Parts by Model Number

Thanks for your thoughts that is what I was thinking too. I can't find the gasket anywhere part #303892 if this is the right part # then I think I will have to make one. I have ordered some gasket material. I'm going to run the motor again today. I put a baby diaper where it is visibly leaking right now to capture that leak and see if it is oozing out somewhere else. Motor is actually starting and running really well. I have a new seal on order and will pull the motor apart when it comes in.

Thanks

 

[budsbait]

Re: 1956 15 HP johnson fuel leak where powerhead meets the lower unit

What troubles me, is why am I getting pure gas and oil at the powerhead to lower unit junction? In my mind, at that point in the engine it should be exhaust with the water mixed with some unburned fuel not pure gas and oil like right out of the gas tank getting pushed out. Maybe if the seal on the crank is really bad then the gas oil mix is blowing by into the lower unit and then finding its way out where the gasket between the lower unit and the powerhead is in bad condition. Guess I really won't know until I start pulling it apart. :grumpy:

 

[budsbait]

Re: 1956 15 HP johnson fuel leak where powerhead meets the lower unit

Okay I pulled the power head. There is a deep jam in the lower unit where the power head attaches just below the carburetor. It looks like someone did it with a screw driver either just trying to separate the pieces or on purpose. I read on one of the threads that there is no way to tell when the seal goes so I'm wondering if someone tried to make a tell tale. The rubber part of the seal actually pulled right out when I pulled the power head off. I'm thinking I want to fill the jam with something. Does anyone know if it is okay to use one of the liquid steel formulas in the small tubes available at most auto stores to fill it with or any other ideas?

 

[OptsyEagle]

Re: 1956 15 HP johnson fuel leak where powerhead meets the lower unit

A picture would help a lot.

 

[Big Jay]

Re: 1956 15 HP johnson fuel leak where powerhead meets the lower unit

Curious if you have figured out this issue....

Any news?

 

[budsbait]

Re: 1956 15 HP johnson fuel leak where powerhead meets the lower unit

Thanks for checking up on me. I believe I've had multiple issues. I pulled the power head and replaced the lower crank seal, which was bad. I used the recommended gasket sealer on the old lower unit gasket and put it on heavy where the gouge was, couldn't find a new gasket anywhere. This stopped the leak between the lower unit and the powerhead joint. However, now I can see it has also been leaking at the crankcase half joint all around really just getting very oily after running for awhile but running fine. Probably just use it as is for rest of this year. When I get a chance guess I will have to pull it apart again and check the mating surface and reseal it. The motor otherwise is in excellent shape inside and out looks almost new under the cover. It does seem to slip once in a while when in drive. It may need a clutch dog. I'll probably have a hard job finding another one.

 

[Daviet]

Re: 1956 15 HP johnson fuel leak where powerhead meets the lower unit

Check your prop hub, might be your slipping problem.

 

[budsbait]

Re: 1956 15 HP johnson fuel leak where powerhead meets the lower unit

Hi thanks for the tip. I didn't know that it was possible to have a bad hub. The prop looks fine but that could be the problem. Actually, it really doesn't act like a clutch dog issue. I have a few of these old OMCs pre 1960 and have had the clutch dog issues before. In my experience it usually jumps out of gear and I have to manually hold it in gear. This problem shows up when going full throttle then I feel a big bump in the boat like I ran over something only lasts a few seconds then just as quickly goes away. Maybe it is a bad prop. How do I check it for sure? Its evidently not completely gone south because most of the time it runs fine even at full throttle. The prop all of a sudden losing grip and then catching again might be the problem.

thanks again for the idea.

 

[F_R]

Re: 1956 15 HP johnson fuel leak where powerhead meets the lower unit

"Feeling like it hit a log" is the classic description of a clutch dog. A prop hub will slip smoothly, like spinning your wheels on the ice.

 

[budsbait]

Re: 1956 15 HP johnson fuel leak where powerhead meets the lower unit

Well it's probably a clutch dog then because it does feel like I hit something but it doesn't jump out of gear like I've experienced with other OMC outboards. I was hoping it would be a prop because they are easier to come by. Any ideas where I can find a clutch dog for a 1956 15hp johnson model FD 10, I'm finding not available so far. Probably not a good idea to run it with the bad clutch dog it might ruin the gear engagement side.

Thanks

 

[budsbait]

Re: 1956 15 HP johnson fuel leak where powerhead meets the lower unit

Sorry spoke too soon I guess I was checking for the wrong engine looks like MarineEngine has them.
375711 - CLUTCH DOG

Part Number
0375711 Johnson
0375711 Evinrude
375711 Johnson
375711 Evinrude


Manufacturer
Evinrude Johnson OMC


List Price
$139.99


Your Price
$83.48

 

[Big Jay]

Re: 1956 15 HP johnson fuel leak where powerhead meets the lower unit

They get ya on the gears boy :rant:

$$$

But on the bright side, you'll be good to go for a long time....

 

[sludgeguy68]

Re: 1956 15 HP johnson fuel leak where powerhead meets the lower unit

Pretty sure those clutch dogs are symmetrical, so if the ears on the reverse-side look decent you could just flip it around for a cheap fix. Then you shouldn't have a problem unless you run it in reverse a lot (backtrolling). I would also check the forward gear and see if it's trashed.

 

[budsbait]

Re: 1956 15 HP johnson fuel leak where powerhead meets the lower unit

HI guys,

Thanks a lot for all of your help. The slipping problem was apparently with the prop hub. I bought a second hand prop put it on and no more bumps in lake. I'll probably be posting more issues as I get this motor up to snuff. Its running well on a 14' mirrocraft pushes it right along. Take care have a nice weekend.

 

[Daviet]

Re: 1956 15 HP johnson fuel leak where powerhead meets the lower unit

Glad you found your problem.