Yamaha 115 Four Stroke - Thermo Assembly

[alumacomp]

My 2002 Yamaha 115 Four Stroke was experiencing excessive exhaust carbon build up on the prop hub and the oil capacity had increased by 1 litre.<br /><br />The dealer diagnosed and replaced a defective thermo assembly (sensor) which senses water temperature. They claimed this defect was causing the motor to run rich, leading to my carbon build up and making oil.<br /><br />Were they correct in stating my problems were caused by this defective sensor?

 

[rodbolt]

Re: Yamaha 115 Four Stroke - Thermo Assembly

beats me. can ya post the resistance numbers he got when testing from cold to warm?<br /> dont have much sensor propblems but its a thermistor device and subject to failure or erroneous outputs. most the time its the thermostat but anything is possible.

 

[bossee]

Re: Yamaha 115 Four Stroke - Thermo Assembly

Hi,<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=30;t=006199 <br /><br />Yamaha has a service bulletin that could cure a making oil problem, see above for what they change.<br /><br />The excessive carbon build up inside prop hub I do not know how it can be cured. I have some carbon build up on my F115 (2003) also but I would not say it is excessive (but I will ask my Yamaha dealer to check on that at next service that will be in a few weeks).

 

[alumacomp]

Re: Yamaha 115 Four Stroke - Thermo Assembly

Rodbolt,<br /><br />I don't have any resistance numbers. The mechanic told me that the fault code came up for the thermo assembly when they hooked the motor up to a laptop.