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72 18Hp Evinrude overheated

R

razorbackgreg

New member
Either the water pump failed or thermo failed on my 18Hp Evinrude while on the lake. Moving along at 3/4 throttle engine slowed and died. Smoke coming from under cowling and the engine paint was coming off. Wouldn't restart. Compression check showed 30 and 60. Removed head and the top piston had material burned from the ridge in the middle. Walls in both cylinders showed some scoring. How bad does the scoring have to be to require a reboring and then oversize pistons? It looks like oversize pistons for this engine are no longer available. My dad gave me this motor and I would like to have it repaired if it is not to unreasonable. It ran like a champ until this happened.
 
Very common for the waterpump impeller to fail.----------They really must be replaced about every 5 years.--------------Where you are located has a lot to do with availability of used parts and even a set of O/S pistons.------------These motors were basically the same for about 20 years so lots of parts around.
 
I live in Montgomery Texas, about 35 miles north of Houston. Is there a good way to tell if a new set of standard pistons and rings will work with the scoring instead of having to use O/S pistons? I've been looking on the web and have had no luck with finding O/S pistons. Do you know a source I can check with on this or know where I can get a good block?
Thanks for any help.
 
Find a website for antique outboards , such as the ---------aomci----------------Post on the webvertize with what you are looking for.---------First take the motor apart / evalute / measure stuff and then decide on a path forward.
 
These motors were basically the same for about 20 years --------Complete lower unit will interchange.----Internal gearcase parts may be different, so the entire unit must be installed if needed.
 
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