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1978 Evinrude (15804B) 15 hp thermostat replacement.

R

RP1

New member
Can the thermostat on a 1978 Evinrude (15804B) 15 hp be replaced without removing the power head? Very tight quarters.
 
Removing the cylinder head is likely the best way.----Loosening the lower cowling may give you extra clearance to remove just the thermostat cover.-----If there was a SEVERE overheat other inspections are needed.----Done a compression test ?----Replaced pump impeller every 5 years or so ?
 
Thanks for the reply racerone! This was my grandfather’s motor, bought new in 1978, taken to Canada on fishing trips for a couple of years, & then he passed in 1983. It hasn’t been run since probably 1982. It has always been stored inside, & it looks brand new. It’s my goal to get it up & running again, and use it myself. My current plan is to replace the water pump assembly, thermostat, fuel lines, & spark plugs, & then see if she’ll start. The plugs were finger tight, & there is fogging oil (or some kind of lubricant) in the cylinders. …….. For the amount of these 9.9 / 15 hp motors that Evinrude produced in that era, it amazes me that I don’t see this thermostat issue discussed in forums, on YouTube, etc. I don’t want to pull the power head if it’s not necessary, but I also don’t want to get it partially taken apart, & still find that it can’t be done, & have to pull the power head.
 
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