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Yamaha C40 2 cycle, where's this spring from?

T

teseal3

New member
I was looking into why Yamaha 40hp C40 would not idle the other day in cold water, 50F, when the last 2 summers it was running good. This was the first time I tried to run it in Dec. Thinking it was related to the water temp I was checking the thermostat and pressure relief valve. When I pulled out the plastic relive valve plunger there was a very small spring laying on top of it, yes it was just setting there. The spring was approximately 1/16" in diameter and about 5/16" long. I'm not by the motor now so I can't post a pic of it but will get one soon. Any ideas what this small spring is from, or is it something the pump picked up and passed along?

By the way the thermostat was closed but the pressure valve grommet was deformed a bit, I'm replacing both.
 
Went down to the boat to get a pic of that spring, OK it is longer than 5/16". The pic is reconstructed to show exactly how I found it when I pulled the plastic valve from the head.20231217_165556.jpg
 
I'm going to go down and check today but I'm pretty certain that my spring is longer than that. I'll post dimensions later today. Thx for your reply. By the way what is that spring from?
 
teseal3 said:
I'm going to go down and check today but I'm pretty certain that my spring is longer than that. I'll post dimensions later today. Thx for your reply. By the way what is that spring from?
Click to expand...
It is shown as being used in the shift shaft support mechanism. Not all models but in some C40's. It is the only spring in a Yamaha that comes close to looking like that which you found.

windows 7 screenshot
 
Guess it would be hard to imagine how a spring from that location would end up in the water path. It also doesn't appear to be similar in shape although it's hard to tell from the diagram. One thing for certain tho my spring is not a compression spring as indicated by the parts description. I appreciate you spending the time trying to come up what it could be but I don't think that's it. Thx
 
Motor is likely due for a new impeller anyway.------I would niot consider it to be " tearing a motor apart " to look at driveshaft seals !
 
Yeah your right its really not the motor work that's bothering me. The boat now is on a floating lift and will need to be towed to the marina dock and trailed home. I live about a half mile into the woods on a winding single lane road with no place to turn around a 24' trailered pontoon boat. I know I know woe is me hey. Guess I better practice my backing skills.
 
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