1998 Yamaha 115 2 stroke - Alarm going off with new impeller and thermostats

[BOAH]

I have a 98 115 2 stroke. I flush it after every use with salt off. I replaced the impeller and both thermostats. Took it out today for first run and alarm goes off when running over 2500 rpms. The pee stream is strong but not very warm. Should it be warm/hot? I was able to make it back by just keeping it below 2000 rpms. I'm always surprised by how much salt and crap is in the thermostats even though I'm good about flushing. My guess is the water passages are getting more and more clogged. Before I pull the heads, can someone give me or point me to a post or video that spells out exactly how to do the vinegar flush?

Thought I would try that before pulling the heads.

Thanks for your help.

 

[99yam40]

look up Rydlyme marine descaler

tell tell should never be hot as it is just an indicator the pump is pumping

Oh yeh, keep running a motor that has a problem like over heat is not a good idea.
shut it off and let it cool off before restarting

 

[BOAH]

I looked at a couple of demos using Rydlyme and looks really impressive. I'll give it a try and report back.

Thanks!

 

[Doh]

I had a similar issue with my 130 V4. The water pump housing wasn't sealing tight against the SS plate. It would pump water until the boat got up on plane enough to bring the housing above water level, and start sucking air around the gap.

Blue RTV, tightened the bolts down, left it over night to set, worked good after.

Oh and make sure the Key is in the slot.

 

[schematic]

look for signs of melted plastic on the pump housing. very sensitive to this....especially behind the cup

 

[BOAH]

Update, I ran the Rydlyme through the system and unfortunately it didn't do it for me. I've been documenting this process and when I'm done, I'll post a video.

I ended up pulling the heads and manually cleaning them. In the process, I've got a spot at the top of the block where the thermostat sits that has been eaten away by corrosion. Amazing it hadn't been leaking but now that I've cleaned it up, it's a hole that goes all of the way through. What could I use to fill it? Will something like JB Weld hold up to temperatures like this?

 

[99yam40]

I had my block welded to fix something like that but inside the housing.
I did add some JB afterwards to fill in the large area inside

 

[BOAH]

I went ahead and used a product called Xtreme Heat. Like a JB Weld but rated up to 500 degrees. The spot is at the top of the block so I'll be able to keep an eye on it to see how it holds up.

 

[Yahman]

OP did you get it resolved? If not also check your poppet valve near the thermostat. It is a simple plastic valve designed to open at higher rpm (above 1500 or so) to let more water through the cooling system. I had a similar issue on my 90 2 stroke i.e. overheating at higher running speeds, but had overlooked this simple item because frankly, I didn't know what it was. (I do now! And it is very important.) Mine was jammed due to salt buildup, a new poppet valve and grommet fixed it. They are only a few bucks and simple to change.And yes JB weld will hold up fine under heat and pressure, I used it to repair a chunked off section of metal around one of my cylinder sleeves.Just be sure to use the regular JB Weld, not the Quickset one, and give it a full 24 hours to cure before you run engine. Miraculous stuff. Good luck!

 

[Yahman]

Sorry, I see you used the Xtreme Heat product. Should be fine with that.

 

[BOAH]

Update. Motor is running great. I'll keep an eye on where I patched the block. I'll post a video on this process as soon as I have it finished.

 

[BOAH]

Here is the video I did detailing the process I took in dealing with this overheating issue. Let me know what you think.