Fifties 7 1/2 OMC

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melugin
Posts: 158
Joined: Mon Mar 16, 2015 9:41 pm
Location: Western Kentucky

Fifties 7 1/2 OMC

Postby melugin » Sun Jul 16, 2017 5:02 pm

What was the main failure point of these motors? I know the '54 Evinrudes had an aluminum exhaust plate which often corroded. I've seen and had more of these with thrown rods than the 5 1/2hp models. Did they usually break or were they discontinued due to too many similar size motors?

FrankR
Posts: 2687
Joined: Tue Mar 10, 2015 6:32 pm
Location: Florida

Re: Fifties 7 1/2 OMC

Postby FrankR » Sun Jul 16, 2017 5:13 pm

I keep harping on the subject of those tossed rods on 5.5 and 7.5hp motors. I submit that most of them are caused by water entry through the lower main bearing due to people ignoring the carbon seal when they do powerhead removal and reinstallation. It takes the water awhile to do it's nasty deed, but it will with time. Then people look at the damage and swear that it was caused by lack of oil. JMHO

Chris_P
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Location: Hamilton ON
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Re: Fifties 7 1/2 OMC

Postby Chris_P » Sun Jul 16, 2017 5:18 pm

Yup, seen ALOT with tossed rods, and found damaged or missing seals on the drive shaft, allowing water in, as Frank stated. Also lots of Ignorants out there on the old internet telling people to run them at 50:1 or some other silly mixture.

ddwilson
Posts: 222
Joined: Wed Mar 11, 2015 1:05 pm
Location: Carmel, IN

Re: Fifties 7 1/2 OMC

Postby ddwilson » Sun Jul 16, 2017 10:30 pm

I have to agree with Frank and Chris. If the seals in good shape and enough oil hard to hurt them. If they broke easy my cousin would have demolished the CD-16 I have when we were growing up. No show winner but starts every time 1-3 pulls even after setting a year.
Doug
Member MOB Chapter
1930 Johnson A50
1932 Johnson K50
1951 Wizard WG7
1953 Wizard WH7
1958 Johnson QD19
1959 Johnson CD16
and the list goes on........


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