96 Yamaha 115 getting overheat alarm

[Fatherbohab]

Ok so I replaced my impeller but I’m getting exactly 35 seconds of full throttle followed by an overheat alarm that lasts exactly 30 seconds. This can happen in a cycle over and over again.

 

[99yam40]

thermostat or blockage in cooling channels

 

[mike_i]

Is it a 2 stroke? if so have you checked the oil level? In my old 2 stroke the low oil alarm and hi temp alarm was the same. When the alarm sounds does the motor go into limp mode? Have you checked the thermostats? What happens if you let the motor idle and not rev it? Does the alarm still sound? Did you have the problem before you replaced the impeller?

 

[LundAngler1650]

Definitely got the correct impeller?

Intake holes are 100% clear, and triple checked?

Thermostat removed, then tried it again, to eliminate that as a cause, and while out anyway, replace with a new one.

Had a customer supply his own impeller last summer, hired me to install it.
Upon looking once I had the old one out, it was the correct diameter, but slightly narrower, I refused to install it, although he kept asking me to. It wasn't a lot narrower, but i bet that bit would have been enough to pump far less water than it should have. Calipers are a great tool.

 

[Fatherbohab]

Is it a 2 stroke? if so have you checked the oil level? In my old 2 stroke the low oil alarm and hi temp alarm was the same. When the alarm sounds does the motor go into limp mode? Have you checked the thermostats? What happens if you let the motor idle and not rev it? Does the alarm still sound? Did you have the problem before you replaced the impeller?

Yes it’s a 2 stroke, funny you mention the oil thing, because I have had a few problems with it not pumping oil from main tank to the tank on motor. When that happens I get alarms and limp mode. If I hit the fill button on motor it fills it up and I’m good. But it doesn’t always do that. I took it in to have that checked, and a new impeller put in. They said it seemed fine but the actual sensor on the oil tank might need replacement. But when that alarm went off all the lights on the dash were on oil temperature everything. First time I took it out after them replacing the impeller that is when this started happening. Idols just fine no problems, it actually I’ll for a good 15 minutes before for I took off because it was in tournament and we are waiting for It to start. Then once I hit it down 35 seconds went by and it threw the temperature alarm and went into limp mode. 30 seconds later on the nose alarm stops all works well. Hit the gas exactly 35 seconds goes by alarm goes off wash rinse repeat over and over and over again to get me home. So far this is where I’m at. I have not checked thermostats or anything else can you check thermostats or do you just have to replace them. I’ve also heard that the water jackets could get plugged not sure how to deal with that myself. do you think that’s a thing a generally handy guy can do or does it need to go into the shop?

 

[99yam40]

pull the stat and place in a pot of water and heat the water while monitoring the temp and watching for when the stat opens to see if it happens in spec.
when you pull the stat look to see how bad the passages look with build up

 

[Fatherbohab]

thermostat or blockage in cooling channels

I’m not an outboard guy, they honestly confuse me. Where are the cooling channels,,and how do I access them?

 

[Fatherbohab]

Ok thank you, now I just need to find where it/ they are. Can’t be to tricky, i need to download a manual.

 

[99yam40]

thermostat controls water flow thru the motor just like on automobiles, it sits in a water cooling passage, so you should be able to see what it looks like when you pull the stat out.
the other cooling passages will require heads and other plates to be removed to inspect and clean if the stat is not the problem

 

[Fatherbohab]

Ok thanks, one thing I forgot to mention. Yeah at full throttle it throws alarms after 30 seconds, but it also does it once I go over 2500rpm. Just cruising at 2500-3000 like 9 mph it did it. I also did full throttle and immediately backed down to 2000 rpm and it still did it. So it’s not just a full throttle thing, it’s an over 2500 rpm thing.