Reply With QuoteYou need to confirm if it's over heating, very common for Yamaha's to have partially blocked cooling passages causing over heating at or over about 4,000RPM, be kind of handy to know what motor it is too.
Hi all,
Any suggestions on why our yami engine would be alarming and starts chugging/ cutting out when we get up to about 4000 revs? This happens in smooth water and choppy water. We just recently purchased the boat and it has been happening since.
Cheers.
You need to confirm if it's over heating, very common for Yamaha's to have partially blocked cooling passages causing over heating at or over about 4,000RPM, be kind of handy to know what motor it is too.
Thanks for your reply. It's a 2 stroke saltwater series.
Above it a video clip of what happens.
You still need to determine what is happening, over heat or lack of oil, I think on that model, only two things set alarm and RPM reduction, over heat (most common) or lack of oil, do the gauges indicate anything? you need to help us to help you.
The gauges don't indicate anything.The oil is fed automatically. We noticed that when the alarm goes off, water starts to come out from the top corner of the motor, you can see this on the video.
Can't see any water coming out the top, but I think that might be a clue! oil is injected, but it doesn't mean it's getting enough oil, can you take the cover off and run it to determine where the water is coming from?
We just brought 2 new thermostats and an impeller, will change them and take it for a run to Moreton this afternoon and see how we go.
Didn’t test drive it before buying ?
Scale build up - can see from pulling thermostats
Over heat from faulty water pump, scale build up, blocked failed thermostats
Failed poppet valve will causing overheating over half constant throttle
Low oil or fawlty oil level sensor
Over revs will generate an alarm too
Replace the water pump and thermostats
Put some premix in the tank and put a mark on the oil reservoir to make sure it’s dropping when used
Stop the premix when your sure it’s working
Take some spare plugs as will be super Smokey and may foul plugs
You said you’ve taken it out of it wasn’t getting oil would have seized by now though
The only fault on that motor that will sound the alarm AND activate RPM reduction is no oil or over heat, seeing as there is water coming out somewhere, I kind of doubt the water pump is bad (but it could be) just as a side note, don't think the RPM reduction is a "limp mode" it is activated because the alarm on it's own was not enough to tell you there's something seriously wrong, do NOT attempt to limp home, if you are getting no oil, limping will stuff your motor, if it's badly over heated, internal parts trying to get external is the next experience! just guessing by what's going on, you have blocked cooling passages (salt away, vinegar and acid will not fix it) or, the leaking water at higher speed is letting the cooling water escape, finding the leak is your first step, not the water pump.
The fact that the engine runs fine, powers up fine, power a along than the alarm sounds once u stop and let the engine idle the alarm goes away its likely stuck closed thermostats
u should really flip the switch under the cowling and fill your oil reservoir manually in a case like this don't rely on it to auto fill because it would have auto filled that whole time u were idling and driving
have u checked the oil level in the main tank in the back of the boat? these run two tanks one in the boat one on the engine
Well.first up you have one of the true classics. One of the most reliable and honest motors to hit the water. I doubt it's thermostats but check and check the pop off valve/diverter. Chances are it's the little holes in the heads blocked with sand (Noel mentioned above). Cheers
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Live: Great South East....love Moreton Bay fishing
Just a hint, if the boat is new to you, it's better to replace the complete water pump kit, not just the impeller, the wear place and the metal insert wear and should be replaced periodically. But, as mentioned before, don't replace anything yet, find that water leak.Originally Posted by sandy21
when you say water comes out of the top of the motor, i can see some dripping coming down the front right corner. this doesnt sound to healthy
@ 1.55 as soon the alarm goes on , see the water spew down the front right over the black yamaha word (small print). maybe thermostat sticky and pressure finding the weakest exit.
If everything is OK, there is no weakest point, unless it has a faulty gasket or a corrosion hole in the block/head somewhere.
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