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Old 06 April 2012, 20:38   #1
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Hot outboard

I ran my newly purchased 15hp Johnson 1999 2 stroke today and I noticed that the leg of the outboard got pretty hot.

Water was coming out the tell tale as it should so I assume the cooling is ok but should the leg get hot? Or is there something wrong?
Thanks
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Old 06 April 2012, 23:12   #2
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Not much in the leg apart from a shaft down to the gearbox, have you checked the oil in the gearbox.
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Old 06 April 2012, 23:13   #3
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However there is the exhaust so that could be what's making it feel warm
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Old 06 April 2012, 23:17   #4
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Had it been the 4 stroke I'd expect the leg to be warm from the oil pan but no a 2 stroke shouldn't be "hot" to touch on its leg.

How hot are we talking ? Was the pumping water warm too ?
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Old 07 April 2012, 00:35   #5
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Warm fair enough. The exhaust is piped down there, and the cooling water should also exit via the same pipe to keep it cool...
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Old 07 April 2012, 08:03   #6
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Thanks for all your replies.

I will probably run it again today and will check again.
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Old 09 April 2012, 00:11   #7
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Is the fuel/oil mix ratio correct?
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Old 09 April 2012, 23:02   #8
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Quote:
Originally Posted by lightning
Is the fuel/oil mix ratio correct?
Hi yes it's run at 50:1 which is what the seller and the manual says it should be.
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Old 11 April 2012, 18:58   #9
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Update.
I've just had a chance to run the OB and the leg is hot after a short period of the OB running.
The tell tale is cool but the leg is probably about the same temperature as a freshly poured cup of tea. Bearable to touch for a short time if that make sense.
Hope someone can help with this or tell me if I'm worrying over nothing.
The OB is a 1999 Johnson J15REEA.
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Old 11 April 2012, 19:29   #10
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Quote:
Originally Posted by lockieboi
Update.
I've just had a chance to run the OB and the leg is hot after a short period of the OB running.
The tell tale is cool but the leg is probably about the same temperature as a freshly poured cup of tea. Bearable to touch for a short time if that make sense.
Hope someone can help with this or tell me if I'm worrying over nothing.
The OB is a 1999 Johnson J15REEA.
It's, normal, the leg is meant to cool from being immersed in water. The exhaust can make it quite hot to touch. I often see steam coming off mine
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Old 11 April 2012, 19:45   #11
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It is normal,the exhaust makes my 15hp warm to touch after a short time.
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Old 11 April 2012, 19:56   #12
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Thanks for clearing that up.
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Old 17 April 2012, 23:16   #13
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Thanks for clearing that up.
Very approximately; pedants welcome to have a go....

Assuming 33% efficiency and WOT, a 15hp engine may be trying to shed 30hp of heat. That's about 20kw. Some is shed via the exhaust gases, some via the water - and remember most cooling water exits via the exhaust too.
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