1985 Yamaha 90ETLK - overheating?

[ctmnsow32]

I took my boat out for this first time this year and about 10 min into driving the motor seemed to suddenly shut down. A steady beeping was sounding when I had the ignition key in the start position. The motor seemed extremely hot, as well as the water coming out of the top. I let it sit for about five minutes, put the key back in and the sound stopped. Then it seemed like the motor was cranking very slowly and did not want to stay on while in a low idle. Does anyone have any idea where I should start troubleshooting this?

[99yam40]

Slow to turn after overheating,
I would start with compression test to see if cylinders/pistons/rings,headgasket were damaged

[ctmnsow32]

Slow to turn after overheating,
I would start with compression test to see if cylinders/pistons/rings,headgasket were damaged

Well the top had a compression reading at 120, middle at 120 and the bottom one had a reading of ZERO. Not good. What are my options at this point...?

[99yam40]

open it up and see what all is wrong with it

[TownsendsFJR1300]

+1 ^^^. You could start by looking down the spark plug hole. Very likely you'll see extensive damage.

Next would be pull the head and see if the block is salvageable. Absolutely zero compression is major damage has likely occurred..


https://www.boats.net/catalog/yamaha...kcase-cylinder

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[zenoahphobic]

Well the top had a compression reading at 120, middle at 120 and the bottom one had a reading of ZERO. Not good. What are my options at this point...?

Zero means the piston, and or piston and conrod, have parted company with the crank shaft.
Given the age of the motor, the only money I would spend would perhaps be on the decal changing the 90 to 60 and sell it as a 60. Sorry couldn't resist.

[ctmnsow32]

Zero means the piston, and or piston and conrod, have parted company with the crank shaft.
Given the age of the motor, the only money I would spend would perhaps be on the decal changing the 90 to 60 and sell it as a 60. Sorry couldn't resist.

So I took a look.... Bottom piston is cashed. A fin on the impeller ripped off and got sent upward causing a clog and preventing water from getting where it needed to go. Resulting in the over heating. I know Zeno says not worth a rebuild does everyone else agree?

[99yam40]

over 30 years old, you will have to look at the condition of all of it to see if it is worth rebuilding

[panasonic]

Lots of things to consider. Overall condition of engine, very high hours or low, how many people owned it, Corrosion.

What do the other cylinders look like? Was it hard to come apart?

Are the parts available. Can you do most of the work yourself?

I seen many engines that old that are in very good condition...Others that need to be unscrewed from the transom and dropped overboard....lol

If you spend say $2000.00 to fix it, that's much cheaper than a new one.

Maybe it is time for a nice quiet four stroke.