1954 Johnson Sea Horse 25 ( Model RDE)

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Snowball70

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Aug 26, 2012
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I'm having problems with my 1954 sea-horse 25 (electric start Model RDE). The motor starts and runs for about 10 minutes after this the engine stalls and appears to be very hot with lots of smoke. After the engine cools down it will run again for 10 minutes and stall again.

Any suggestions? Also, what's recommended for oil to gas ratio currently I'm using 50:1.

Thx in advance.
 
nwcove

nwcove

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Re: 1954 Johnson Sea Horse 25 ( Model RDE)

50:1 will kill your motor! id go with 16:1 mix or 24:1 bare minimum. sounds like its time for an impeller !
 
D

Daviet

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Re: 1954 Johnson Sea Horse 25 ( Model RDE)

Have you looked at the exhaust port, is there water coming out? Could be overheating
I think that engine was suggested to run a 24:1 gas/ratio when it was new. I think it has roller bearings on the crank, so you should be able to run a 50:1 ratio, using today's oils.
I am sure someone will chime in with more advice.
 
HighTrim

HighTrim

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Re: 1954 Johnson Sea Horse 25 ( Model RDE)

50:1???Yikes 24:1 is what you need.

I hope you are not running it dry without proper cooling? As stated, there should be a mist exiting the exhaust port.

Step 1 will now be to check compression to see if anything got damaged.
 
T

twocyclemania

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Re: 1954 Johnson Sea Horse 25 ( Model RDE)

I would look at the water pump impeller and the head gasket.
 
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Snowball70

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Re: 1954 Johnson Sea Horse 25 ( Model RDE)

Daviet said:
Have you looked at the exhaust port, is there water coming out? Could be overheating
I think that engine was suggested to run a 24:1 gas/ratio when it was new. I think it has roller bearings on the crank, so you should be able to run a 50:1 ratio, using today's oils.
I am sure someone will chime in with more advice.
Click to expand...


Thx for the info yes there is water coming out of the exhaust port.
 
lindy46

lindy46

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Re: 1954 Johnson Sea Horse 25 ( Model RDE)

If the head is so hot you can't touch it, or if you splash water on it and it boils, you're overheated.
 
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