Johnson 50esl73r hole in crankcase

S

scragglygoose

Recruit
Joined
Jul 18, 2011
Messages
3
Hi, first poster here! I have a Johnson 1973 50 hp that has blown a hole in the side of the crankcase on the top cylinder. I also have a 1974m model that I got when I bought the boat that had the same problem and was re-welded. Can anyone tell me if this is/was a common problem with these old motors? It is odd that both motors have the same problem in the same general area. The case seems very thin at the point it blew out. How is the best way to repair this? Welding? Does the entire powerhead have to be torn down to re-weld? Thanks and I'll post a pic.
The starter motor was removed for photo clarity.
 

Attachments

  • pic1.jpg
    pic1.jpg
    123.8 KB · Views: 0
  • pic2.jpg
    pic2.jpg
    80.6 KB · Views: 0
W

wilde1j

Vice Admiral
Joined
Apr 15, 2002
Messages
5,964
Re: Johnson 50esl73r hole in crankcase

It didn't just "blow out". Typically this happens when internal moving parts come apart (like a con rod, etc.). If you open the motor, I'll bet you'll find something 'exploded' inside. It's not common at all, other than in cases of thrown rods, etc.
 
Wrongsyde

Wrongsyde

Petty Officer 3rd Class
Joined
Jun 24, 2010
Messages
77
Re: Johnson 50esl73r hole in crankcase

Whew, that's a good one! I suggest you don't try to start it up like that. ;)
 
S

scragglygoose

Recruit
Joined
Jul 18, 2011
Messages
3
Re: Johnson 50esl73r hole in crankcase

The motor runs with this hole in it, it happened while on the water so I can't think that there would be something exploded inside because we ran the motor in order to get back to the dock. That and the fact that I have a 1974 model motor with the same problem seems a little strange.
 
J

jayyyy

Seaman
Joined
Jul 17, 2011
Messages
52
Re: Johnson 50esl73r hole in crankcase

Usually when there is a hole in the crankcase its from a broken con rod, rod cap or piston/wrist pin. Could be the motor threw a rod and during the rebuild someone patched with jb weld etc. and the patch fell off. It should be tig welded and ground flush on the inside. I would have a professional look at it.
 
mstahl1171

mstahl1171

Petty Officer 1st Class
Joined
Mar 16, 2010
Messages
209
Re: Johnson 50esl73r hole in crankcase

WOW....something is not right for sure. Maybe it was a bad casting?? metal fatiuge??...but 2 motors with the samething...buy a lotto ticket...lol Get it checked out by a pro...keep us posted
 
B

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: Johnson 50esl73r hole in crankcase

Don't run it that way or you could have a fire on your hands. Seen it happen before.
 
S

scragglygoose

Recruit
Joined
Jul 18, 2011
Messages
3
Re: Johnson 50esl73r hole in crankcase

well I'm definitely going to pull it apart and find out what happened and have it welded up. I found another pic that was posted on this forum about a year ago that had this same problem. pic attached of 55 hp 1978 model. This is what led me to think that it might be a metal fatigue problem. Will let you know what I find out.
 

Attachments

  • Johnson_55E78S_crankcase_hole.jpg
    Johnson_55E78S_crankcase_hole.jpg
    131.3 KB · Views: 0
C

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
29,031
Re: Johnson 50esl73r hole in crankcase

My old fat fifty had a hole in the front of the crankcase, when I got it. It had been epoxied over. I assumed the motor fell over(or something) when being installed since that part of the motor did not have moving parts. I never had any issue with it.

Those holes must be investigated and the cause found. also the crankcase needs to be sealed for the motor to run properly.
 
You must log in or register to reply here.
Top