Bout Time 1 Posted December 29, 2017 Report Share Posted December 29, 2017 Lately I ‘ve been getting the overheat alarm and then Limp mode only at high RPM, like close to WOT. If I shut it down, wait 30 seconds and turn the key on, the alarm goes off and I can run all day under 4500 rpm. I started out by changing thermostats, checking the poppet valve (old style) and cleaning it. No change. Recently put a new water pump in. No change. Checked both thermo switches per the repair manual. They are both good. Pulled the heads and checked all water jackets. Some minor blocked areas but have always flushed with ears with fresh water after running in salt. Heads looked pretty good. Cleaned everything up and installed new head gaskets. I also installed the new mushroom style poppet valve. I’m hoping I finLly got this solved but cold and rainy here so no trial run yet. Had anyone had a similar problem? Could it be the poppet valve? I swear the old one looked fine. Thanks. PS this engine has 588 hrs on it Quote Link to comment Share on other sites More sharing options...
Lap it Up Posted December 29, 2017 Report Share Posted December 29, 2017 The new poppet is a big improvement over the old style. Yamahas are very sensitive to blockage in the water jacket passages. I plastic bead blast the heads and jacket covers to get rid of all the scale and build up. I also lap the heads flat again. Try Mary Kate On/Off in a squirt bottle for the passages in the block. use lots of water to clean it all out. Hopefully your issue isn't a corrosion hole in the exhaust plate mixing exhaust and cooling water. Quote Link to comment Share on other sites More sharing options...
dabear Posted December 29, 2017 Report Share Posted December 29, 2017 Overheating after running over 4500 RPM sure sounds like restricted water flow in the cooling system . Quote Link to comment Share on other sites More sharing options...
Bout Time 1 Posted December 30, 2017 Author Report Share Posted December 30, 2017 Agreed. Thanks guys. I hope I got this solved. I’ll update the post after a trial run. Ran it today in the shop and had no leaks. Thats a good thing!! Quote Link to comment Share on other sites More sharing options...
Bout Time 1 Posted December 30, 2017 Author Report Share Posted December 30, 2017 When I bought the gaskets at Atlantic Coast Marine here in Jax I asked about the exhaust plate and the water tube grommet. They said they rarely get that repair into the shop but have done a ton of the poppet valves. I got my fingers crossed. Quote Link to comment Share on other sites More sharing options...
polliwog Posted January 4, 2018 Report Share Posted January 4, 2018 Had the same engine ,same yr. It is a great engine, mine finally died of water jacket corrosion. I never had a over heating alarm. Mine was kept in water at a brackish water marina. Hope yours is ok,600 hrs is nothing for that engine. Mine had well over 1500 hrs. You just don't that power sound from the 4 strokes. Quote Link to comment Share on other sites More sharing options...
Bout Time 1 Posted January 4, 2018 Author Report Share Posted January 4, 2018 Still have not had a chance to run it WOT yet. Dang cold weather!! Hope its ok. Quote Link to comment Share on other sites More sharing options...
captpn Posted January 16, 2018 Report Share Posted January 16, 2018 Had the exact same issue on a previous yamaha. Replaced everything without solving the problem. Finally pulled the heads, cleaned up the passages, and problem solved. You should be good to go. Mine looked just like yours, which Id consider pretty clogged. How did it go? Quote Link to comment Share on other sites More sharing options...
Bout Time 1 Posted January 21, 2018 Author Report Share Posted January 21, 2018 Well finally got it out today. Ran it WOT up the ditch and it never overheated. That’s a plus. However the last couple times I’ve taken it out it has been smoking from under the powerhead and today I recorded the leak. Looks like the powerhead is coming off to change the exhaust seal which also has the water tube from the water pump running thru it. Does not leak like this when running at home with the ears on. Just when its in the water. B-O-A-T.....lol 31E1947A-FC65-421C-9CEE-291BAD3219AC.MOV Quote Link to comment Share on other sites More sharing options...
Bout Time 1 Posted January 21, 2018 Author Report Share Posted January 21, 2018 Quote Link to comment Share on other sites More sharing options...
Bout Time 1 Posted January 21, 2018 Author Report Share Posted January 21, 2018 B6C7F8D3-E521-4916-84FA-77F8BC76B54A.MOV Quote Link to comment Share on other sites More sharing options...
Desperado213 Posted January 31, 2018 Report Share Posted January 31, 2018 My motor is having the same issue. I am going to upgrade the poppet valve soon and test the thermostats. I am hoping that fixes the issue. Quote Link to comment Share on other sites More sharing options...
Bout Time 1 Posted January 31, 2018 Author Report Share Posted January 31, 2018 Update: Took my boat to a mechanic here in Jax cuz I didn’t want to tackle pulling the power head. Even though I changed the poppet valve, once he got the powerhead off he found that the other end of the hose from the poppet valve spring assembly was clogged solid. Also the power head gasket was roached. He charged me 300.00 labor and about 60 bucks in parts for the gasket, a new hose and the nipple on the return end of the hose. I think I got off cheap! I should be good for awhile now!! Glad no holes in block or exhaust plate! Dude is a solid fair mechanic! Thanks Chris!! Quote Link to comment Share on other sites More sharing options...
lurem Posted January 31, 2018 Report Share Posted January 31, 2018 in the first picture, the rubber hose with the zip tie was clogged on my 115. I replaced the rubber hose, spring, valve and metal connector that was on the block. I guess salt deposits build up there over an extended period of time. good find! Quote Link to comment Share on other sites More sharing options...
Bout Time 1 Posted January 31, 2018 Author Report Share Posted January 31, 2018 Yep, I replaced the spring, valve and grommet but not the hose. I however did not check the other end of the hose where it enters the mid section. That’s where the bad clog was. So this time the hose and that return nipple get replaced after cleaning out the clog. Quote Link to comment Share on other sites More sharing options...
lurem Posted February 1, 2018 Report Share Posted February 1, 2018 Is that spring and valve what everyone is calling a poppet valve? What is its function? Besides clogging with salt deposits and causing us grief? Haha Quote Link to comment Share on other sites More sharing options...
Lap it Up Posted February 1, 2018 Report Share Posted February 1, 2018 6 minutes ago, lurem said: Is that spring and valve what everyone is calling a poppet valve? What is its function? Besides clogging with salt deposits and causing us grief? Haha Poppet valve allows cool water to stay in the block while idling or running at very low RPM. The poppet opens (from pressure) at higher RPM when the flow from the water pump is a lot more. 1 Quote Link to comment Share on other sites More sharing options...
Lap it Up Posted February 1, 2018 Report Share Posted February 1, 2018 14 hours ago, Bout Time 1 said: Update: Took my boat to a mechanic here in Jax cuz I didn’t want to tackle pulling the power head. Even though I changed the poppet valve, once he got the powerhead off he found that the other end of the hose from the poppet valve spring assembly was clogged solid. Also the power head gasket was roached. He charged me 300.00 labor and about 60 bucks in parts for the gasket, a new hose and the nipple on the return end of the hose. I think I got off cheap! I should be good for awhile now!! Glad no holes in block or exhaust plate! Dude is a solid fair mechanic! Thanks Chris!! Indeed you got a fair deal there! I assume he didn't break any bolts which is rare on an aged Yamaha. Only thing I may have opted for would have been new upper motor mounts since he was in there. The rubber looks pretty tired. Quote Link to comment Share on other sites More sharing options...
Bout Time 1 Posted February 1, 2018 Author Report Share Posted February 1, 2018 Yeah I asked the same question when I saw them but the picture makes them look worse than they are and since he has not had any broken bolts yet I didn’t want to push my luck. Those mounts could get pricey if a bolt broke and they really aren’t that bad. Have not had any shaking at all. Quote Link to comment Share on other sites More sharing options...
Desperado213 Posted February 1, 2018 Report Share Posted February 1, 2018 Could you access the other end of the hose from the poppet with the motor still mounted or is it too tight of space? Quote Link to comment Share on other sites More sharing options...
Bout Time 1 Posted February 1, 2018 Author Report Share Posted February 1, 2018 Might have to remove one of the side panels. Not sure but will check when I get it back Saturday. Gonna pick up the boat and splash it on way home to check it all out. Quote Link to comment Share on other sites More sharing options...
Bout Time 1 Posted February 4, 2018 Author Report Share Posted February 4, 2018 Update: my mechanic got the engine back together and I still have a leak. The water leak is coming from somewhere in the exhaust plate. Probably the water tube grommet. It’s all apart again to dig further. Getting more expensive by the day!:( On a good note he has not broken any bolts yet miraculously. Quote Link to comment Share on other sites More sharing options...
Bout Time 1 Posted February 14, 2018 Author Report Share Posted February 14, 2018 Finally got the boat back. Leak was in the exhaust plate. Sand clogged in discharge holes in base plate as well as old leaking grommet on water tube. Good to go now. Just in time for a trip to Rodman! Quote Link to comment Share on other sites More sharing options...
lurem Posted February 14, 2018 Report Share Posted February 14, 2018 Whoo hoo! Quote Link to comment Share on other sites More sharing options...
Bout Time 1 Posted May 15, 2018 Author Report Share Posted May 15, 2018 Boat running great now had it out several times and have run it WOT with no issues. Glad To have it back right again. All waxed up and ready to ride. 1 Quote Link to comment Share on other sites More sharing options...
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