What is it part ? Re: 1975 Evinrude 25 hsp

Ned120

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Aug 8, 2008
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Directly beneath the carb, is a hose nipple for a very narrow inner diameter hose that loops up to the top left of the motor (facing it from the carb) and plugs into another nipple, not well described in the Clymer manual,that is my only source of help, but possibly the exhaust cover. The only vague reference in the manual is to an "outboard water indicator hose" . No idea if that is what this part really is. The old hose was bad and I replaced it with a piece of clear narrow diameter fuel line. Once I got the motor started, it bucked each time a droplet of fluid was pulled up the line by the action of the motor running. What is this hose and what's its function? many thanks for all responses.
 

Chinewalker

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Aug 19, 2001
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8,902
Re: What is it part ? Re: 1975 Evinrude 25 hsp

It's a recirculation hose. It takes unburned fuel/oil mix from the bottom of the cankcase where it tends to collect and uses crankcase pressure to feed it to the top of the crankcase. This gives a little extra lube to the upper bearing and also helps the motor burn off the extra fuel...
 

F_R

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Jul 7, 2006
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28,226
Re: What is it part ? Re: 1975 Evinrude 25 hsp

It's a recirculation hose. It takes unburned fuel/oil mix from the bottom of the cankcase where it tends to collect and uses crankcase pressure to feed it to the top of the crankcase. This gives a little extra lube to the upper bearing and also helps the motor burn off the extra fuel...

Or, possibly he is speaking of the crankcase drain hose, goes to the upper bypass cover. In bygone years, the crankcase drainage was merely dumped overboard. Due to environmental concerns, it was then dumped into the upper cylinder via the bypass cover, where it hopefully gets burned. Sounds noble, but doesn't really burn that well and causes rough idle.
 

Ned120

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Re: What is it part ? Re: 1975 Evinrude 25 hsp

Thanks, that nails it pretty well. My theory was that it was something like that. Appreciate the help.
 
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