1994 Johnson 120 Lower crankshaft bearing replacement project J120TLER

[jstatham]

Hello everyone. I wanted to give you an update on the lower crankshaft bearing replacement project. For those of you who have helped I have linked the previous thread trying to determine the problem.
http://www.screamandfly.com/showthre...ght=frustrated

http://www.thehulltruth.com/boating-...rustrated.html
I hope this will help someone else one day. I am by no means a professional mechanic but I do know how an engine works and I do all my own automobile repairs. I have done everything from brakes to install motors. if I am not exactly right on everything don’t hate me I am just trying to help someone else down the road. Any advice or suggestions will be greatly appericated.

My Motor is a 1994 Johnson 120 TLERC
#1. Here are the symptoms of a bad lower crankshaft bearing. You hear a grinding noise in the motor while running it. The flywheel is popping up and down and the motor is spitting and sputtering and blowing off the fuel overflow lines. You will see cracks and holes on the crankcase near where the lower unit rod hooks up. You may also see metal flakes all over the motor. They are pieces of the bearing that are blowing out of the hole in the crankcase. Once you have determined it is a bad bearing it is time to get to work.

1. You have to remove the power head and get it somewhere where you can work on it.
2. Remove the carbs,intake, flywheel, starter, stator, timing piece, upper and lower covers and anything else I left off. Here are a few videos I made documenting the process for future reference as well as a few pictures.
intro
http://home.comcast.net/~kstatham/1intro.mov

http://home.comcast.net/~kstatham/2hoist.MOV

http://home.comcast.net/~kstatham/3hoist.MOV

http://home.comcast.net/~kstatham/3holeincase.MOV

http://home.comcast.net/~kstatham/4carbsoff.MOV

http://home.comcast.net/~kstatham/5flywheeloff.MOV

http://home.comcast.net/~kstatham/6bearing.MOV

3. After you get the crank case apart inspect for damage. Mine was cracked and had 1 small hole and stress cracks. I took the case to one of my friend’s house who welded it for me. Below is the before and after picture. The inside is fine because where the hole is located is the open space for the crank case to rotate.









4. This weekend I plan on getting everything cleaned up so the crankcase surfaces will seal. I am also going to paint over the welds with Hi-Temp black paint. I am also going to remove/pull what’s left of the old bearing and clean out all the metals flakes with brake cleaner/ air and vacuum. Depending on what parts come in I will start installing what I can but don’t expect to have all of them in until mid-next week. I basically had to order a new bearing, sleeve and o rings, etc. My sleeve was completely gone. This where I am at today I will update as I progress but I would love to her comments or suggestions if you see I am doing something wrong. Like I said before I am no expert I am going by the book and what I am seeing online as well as I have contact to a marine mechanic. Other than that it is the school of hard knocks and learn as you go. I do have one question what would you recommend to seal the crankcase? I know the gel seal II but is there an equivalent I could pick-up at my local Auto Parts Store.

[RoyE]

Any updates?

[jstatham]

Oh yeah I have posted to several forums all over the internet but to catch this thread up here is where I am at. I have been troubleshooting every weekend (when time Permits) and it has been a real headache. I got it all put back together and it still ran like crap. I have one cylinder (Plug) that was always soaking wet when I run it. During the troubleshooting process I discovered the upper crankshaft seal was leaking. I should of replaced it when I had the motor apart but being inexperience I did not replace. I also found the stator was weak. I replaced the stator and it fires up and starts much better. I also discovered that the fuel primer gasket was backwards and leaking. Once I got all that replaced I still have the wet plug. If I move the carb on that cylinder to another the wet plug always follows that carb. I checked and rechecked the carb and I finally discovered that the float bowl on the carb and the carb itself is warped. From what I have read that was a common problem. I actually found the exact part# guaranteed to be good on Ebay and I hope to have it by this weekend to finally get this thing running right. As for now it us running on 3 cyclinders.

To recap Here is all I have replaced since the latest post.
1. New Upper Crank Seal
2. Plugs
3. Stator
4. Carb
5. A ton of time troubleshooting and testing everything you can think of and I think I finally know what's going on. More to follow.

[RoyE]

I'm feeling exactly the same as you right now, having several issues, now sorting out a idle problem. Has me occupied every weekend this problem.

How did you determine the stator was weak? Low output?
How did you see the upper seal was leaking?

My float bowls were all warped, I wet sanded them on 600 grit, made no difference in how the engine runs.

Also see: iboats , if you have any suggestions for me.

Keep us updated, I'm very curious.

[jstatham]

I feel your pain. I used a homemade dva adapter to test the stator output and mine was way too low out of spec. The new one is much higher and hot.

To test the upper seal I cranked up the motor and squirted starter fluid under the flywheel while it was running and it started running much better. Any change in RPM's tells you there is a leak. Here is the video I made of me testing the crankshaft seal. You can also take off the flywheel and pour a little 2 stroke oil on top of the seal. Then put the nut on it and rotate the engine and if you see any bubbles in the oil it is leaking.

https://www.youtube.com/watch?v=L0N7vyc98uA



Here is a leak to all of my videos.
https://www.youtube.com/channel/UC7Y...DWGIvO2KdORJnQ


What does your plugs look like? My friend who is a marine mechanic told me that he has seen it where you cannot fix the warped carbs.

[jstatham]

I think this is all the places I posted.

http://www.screamandfly.com/showthre...34#post2700534
http://www.screamandfly.com/showthre...ght=frustrated
http://www.thehulltruth.com/boating-...rustrated.html

http://forums.iboats.com/forum/boat-...a-adapter-help
http://forums.iboats.com/forum/engin...nd-thermostats
http://forums.iboats.com/forum/engin...elp-frustrated

[Jason Joe]

I don't know if you've tried any of my previous suggestions but I would look at those brass tubes that run from the bowl to the idle and intermediate circuits for blockages. Also I notice in one of your videos that #2 plug wire has the shallow boot on the plug make sure it has a shallow boot on the coil. It might have two shallow boots but it might also be reversed. I still think it sounds lean not rich on one or more cylinders sometimes plug reading at an idle can be misleading.

[jstatham]

I have had the carbs out and cleaned several times. It is 100% clean. I hope the new carb solves the problem. I will let you know.