Topic: Top speed with 18hp Evinrude on 14′ aluminum – Page 9

This topic has 105 replies, 22 voices, and was last updated 7 years, 1 month ago by stephenspann27.

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February 19, 2017 at 2:07 pm #53257
stephenspann27
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I"m going to cave in today and yank the powerhead and start pulling it apart until I find something wrong.
February 19, 2017 at 3:59 pm #53267
Mumbles
Participant
Hold on a moment before you do anything drastic. The last step on the brass plate might make contact with the block at WOT, not the shift lock lever. I’m sure some models do. There’s a few 18’s in the garage so I’ll take a look when I go out there.

Do you know if any mag parts have been swapped around in the past? There’s a reason that shift lock lever has been shortened and the motor not making full RPM could be it.
February 19, 2017 at 4:33 pm #53268
Mumbles
Participant
On this ’65 FD with a ’72 Evinrude powerhead/mag on it, at max throttle the brass plate does make contact with the lock lever but on this ’63 Gale built 15, the contact is made on the starboard bracket, leaving a slight air gap between the plate and the lever. Hmmmm…..

I have more 18’s but they aren’t handy at the moment.

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February 19, 2017 at 4:54 pm #53269
Mumbles
Participant
Going thru this thread again, I think you have already shown us the problem.

The pistons and rings in your white Ebay motor are scored. The motor will never be able to develop its designed horsepower in that condition. Pistons, rings and cylinder walls should be smooth with no grooves or scoring for the rings to seal correctly. Bottom line, the motor is tired and needs attention.

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February 19, 2017 at 5:19 pm #53275
stephenspann27
Participant
The above is correct, I just thought since it had good compression and passed the leak down test it was worth trying some other things. I tore the powerhead all the way down this morning. Not a single gasket was leaking, the burn looked even between the cylinders according to the piston tops and the carbon on the head. No smoking guns as far as getting fuel/air in and out of the motor. The verdict is a like mentioned above, the pistons and rings are scored. The rings are still free on the pistons, and bores are not terrible. The motor has definitely been hot. The crank bearing surfaces are blue from running hot. The crank bearing surface at the top (where the seal was leaking) is trashed. The crank out took out of my original, blue powrehead is actually in better shape than this one. Pictures in the next post.
February 19, 2017 at 5:21 pm #53276
stephenspann27
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February 19, 2017 at 5:22 pm #53277
stephenspann27
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Crank from teh white powerhead on the right
February 19, 2017 at 5:24 pm #53278
stephenspann27
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February 20, 2017 at 4:05 am #53313
david-bartlett
Participant
Stephen,

That one is surely worn out. It is like Bill W said, they will continue to run way beyond when they should quit. Time for a new powerhead on your otherwise good motor.

In your next to last picture, the reed plate looks like one of the reeds was not lined up properly to seal. Maybe this happened when you took it apart. NOt really an issue now, but was just curious if this had anything to do with your dry spark plug issue.
February 20, 2017 at 11:26 am #53319
stephenspann27
Participant
quote david bartlett:

Stephen,

That one is surely worn out. It is like Bill W said, they will continue to run way beyond when they should quit. Time for a new powerhead on your otherwise good motor.

In your next to last picture, the reed plate looks like one of the reeds was not lined up properly to seal. Maybe this happened when you took it apart. NOt really an issue now, but was just curious if this had anything to do with your dry spark plug issue.

On the reeds, yea that was my fault, I had taken them apart then just slapped them together. The motor was really in great shape as far as gaskets, torque specs, and corrosion.
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