Leeverwitz
New member
Hello all,
First time entry here and first time forum entry ever so go easy on me. I have a 2002 25HP Yamaha Four Stroke and recently discovered water in the oil. Took it over to someone that had a little experience with outboard motors and we also noticed a significant amount of blowback coming from the dip stick hole (finger over hole showed more than normal pressure) So we both through our hands up and thought it could be the block or a blown ring becasue of all the blowback. Idles fine, just the oil in the water seems to be the mystery...* Anyways, I went to my local Yamaha dealer and told him about the water in the oil and the blowback and he instantly said, "the thermostat is stuck open, i see it all the time." What?? How could a failed thermostat put water in the oil?? So I went ahead and bought the thermostat and sure enough I went home, opened up the thermostat housing and the thermostat was corroded open, so I replaced the thermostat with hopes of fixing the problem but I need some help understanding why a failed thermostat would allow water to get in the oil?? If you could also explain why that would induce heavy blowback that would be great! It just seemed strange that a new thermostat would correct the water in the oil scenario... Now I suppose in the end it could be something else, but I just need some help understanding that whole situation. Thanks much and look forward to your responses!
First time entry here and first time forum entry ever so go easy on me. I have a 2002 25HP Yamaha Four Stroke and recently discovered water in the oil. Took it over to someone that had a little experience with outboard motors and we also noticed a significant amount of blowback coming from the dip stick hole (finger over hole showed more than normal pressure) So we both through our hands up and thought it could be the block or a blown ring becasue of all the blowback. Idles fine, just the oil in the water seems to be the mystery...* Anyways, I went to my local Yamaha dealer and told him about the water in the oil and the blowback and he instantly said, "the thermostat is stuck open, i see it all the time." What?? How could a failed thermostat put water in the oil?? So I went ahead and bought the thermostat and sure enough I went home, opened up the thermostat housing and the thermostat was corroded open, so I replaced the thermostat with hopes of fixing the problem but I need some help understanding why a failed thermostat would allow water to get in the oil?? If you could also explain why that would induce heavy blowback that would be great! It just seemed strange that a new thermostat would correct the water in the oil scenario... Now I suppose in the end it could be something else, but I just need some help understanding that whole situation. Thanks much and look forward to your responses!