1977 115hp Johnson overheating alarm

[aintnever]

I recently purchased a 115 hp powerhead for my boat. I installed the powerhead and was able to get it to idle in the yard with the muffs on. The next day my wife and I took the boat out for a water trial. It ran for about 5 mins and the overheat alarm came on. I quickly turned the motor off and proceeded to troll back to shore. Got the motor home and hooked up the muffs and the motor fired up and ran great for about 10 mins. The mechanic I purchased the powerhead from also sold me a thermostat plastic housing block. He advised me to remove the thermostat and just put the spring and flat nipple in the bottom hole of the housing. This really doesn't seem to make sense to me because there is nothing to push that nipple back. Also, what was supposed to go into the top hole of the housing?? Is this the cause of my overheating??

 

[ezeke]

Re: 1977 115hp Johnson overheating alarm

There are different models of 115 Johnson in 1977. The ones with extra long shafts have two thermostats (vernatherms), while the long shaft models have only one.

Click the thumbnail for a diagram of the thermostat system for the longshaft model.

The part numbers are listed in the parts catalog for your model under the exhaust housing diagram: http://shop.evinrude.com/

The V4 crossflow motors can overheat from a weak waterpump, from a failing thermostat, or from water passage deflectors that have moved.

If you were running without thermostats when the engine overheated, chck the water passage deflectors.

 

[aintnever]

Re: 1977 115hp Johnson overheating alarm

Thanks for the detailed diagram. Is there a diagram that shows placement for the water deflectors??

 

[steve6]

Re: 1977 115hp Johnson overheating alarm

try this,

http://shop2.evinrude.com/Index.aspx?s1=f084de38d6617de8c51f56f8fce6e24a&catalog_id=5&siteid=1

select your year, and motor , and look for the components they are talking about..

 

[ezeke]

Re: 1977 115hp Johnson overheating alarm

Thanks for the detailed diagram. Is there a diagram that shows placement for the water deflectors??

Yes