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Message
Yamaha 90 HP overheating while peeing
Posted on 10/8/24 at 4:43 pm
Posted on 10/8/24 at 4:43 pm
I’m at a loss with this outboard.
It overheats in idol but not if I’m running at higher rpm’s.
I’ve changed the poppet valve, thermostat, impeller blade and kit. I run it with muff and in a tank to check it but after about 10 minutes it over heats. It seems the poppet valve does stick but if I remove it and put it back together it will be free to move again.
If I flush it from the top hose flush it pees a hard stream. If I flush it with muffs or in the tank it’s a weak stream.
I have flushed from the top and then reversed it with muffs and it will not pee at all. So it had me thinking there’s an obstruction in the tube on the way up from the bottom intake. I’ve taken it all apart but can’t find anything. Ran a wire up the intake tube (metal tube) and got nothing. Seems clear all the way to the engine.
Any thoughts on what to try next? Is there a way for me to clean out the water flow in the actual engine? I can’t get to the top of the tube but I think if I could I could push it out.
I’m thinking it’s a piece of the old impeller blade. It was broken off.
It overheats in idol but not if I’m running at higher rpm’s.
I’ve changed the poppet valve, thermostat, impeller blade and kit. I run it with muff and in a tank to check it but after about 10 minutes it over heats. It seems the poppet valve does stick but if I remove it and put it back together it will be free to move again.
If I flush it from the top hose flush it pees a hard stream. If I flush it with muffs or in the tank it’s a weak stream.
I have flushed from the top and then reversed it with muffs and it will not pee at all. So it had me thinking there’s an obstruction in the tube on the way up from the bottom intake. I’ve taken it all apart but can’t find anything. Ran a wire up the intake tube (metal tube) and got nothing. Seems clear all the way to the engine.
Any thoughts on what to try next? Is there a way for me to clean out the water flow in the actual engine? I can’t get to the top of the tube but I think if I could I could push it out.
I’m thinking it’s a piece of the old impeller blade. It was broken off.
9
Posted on 10/8/24 at 8:53 pm to tigereye58
It’s gotta be something with the impeller. No other reason for it to be over heating.
2 or 4 stroke? Have you checked the oil? Are you using the correct oil?
2 or 4 stroke? Have you checked the oil? Are you using the correct oil?
Posted on 10/8/24 at 10:02 pm to Doby
It’s a 4 stroke. I just using your typical outboard oil. I’ll have check the brand. It’s ran fine with this oil in the past. But always a possibility the oil pumping enough. But it does cool at higher rpm’s.
Posted on 10/9/24 at 5:01 am to tigereye58
Did you put the key in the impeller?
Does it have water pressure in the powerhead? You need to figure that out, to determine if it is pumping or not. Report back when you know that.
Does it have water pressure in the powerhead? You need to figure that out, to determine if it is pumping or not. Report back when you know that.
Posted on 10/9/24 at 6:19 am to tigereye58
Is the impeller blades fold in the housing the correct way?
Posted on 10/9/24 at 6:49 am to tigereye58
Had the same issue after I changed mine a few years back. Check the water intake side screens or ports on the lower unit. My old impeller had some parts that had broken off and those pieces were keeping it from getting enough water to cool the engine.
Posted on 10/9/24 at 7:32 am to tigereye58
My Suzuki will only flush with the round muffs, if you use the other muffs it doesn’t flush at all. Doesn’t make any sense they both seem to hold suction. So be careful with that.
I would point to it being an impeller issue.
Are you saying the same thing happened before changing the new impeller, you put a new impeller on, and it continued to happen? Or it’s a new impeller and it’s happening?
ETA: also if it’s only happening during low rpm/ idle I’d put that in the thread title as that’s very important. Sounds like it’s a pressure issue and not getting the proper flow at low rpm
I would point to it being an impeller issue.
Are you saying the same thing happened before changing the new impeller, you put a new impeller on, and it continued to happen? Or it’s a new impeller and it’s happening?
ETA: also if it’s only happening during low rpm/ idle I’d put that in the thread title as that’s very important. Sounds like it’s a pressure issue and not getting the proper flow at low rpm
This post was edited on 10/9/24 at 7:33 am
Posted on 10/9/24 at 7:38 am to DownshiftAndFloorIt
It’s a new impeller. I actually took it apart again to make sure it was installed spinning it the correct direction. Both times it’s still a weak stream and eventually overheats.
How to I check the pressure in the power head? I’m not sure what the key is? There’s a piece of metal in the shaft when I changed it and I replace that also.
I’ve tried round muffs, square muffs with flow on both sides and put it in a tank yesterday.
How to I check the pressure in the power head? I’m not sure what the key is? There’s a piece of metal in the shaft when I changed it and I replace that also.
I’ve tried round muffs, square muffs with flow on both sides and put it in a tank yesterday.
Posted on 10/9/24 at 7:43 am to tigereye58
Posted on 10/9/24 at 9:43 am to tigereye58
I have a Yamaha 25 4 stroke that ingests a lot of sand.
I've had to remove the intake screens, remove thermostat, remove any brass hose fittings and coolant hoses. I blew compressed air, used weedeater string to chase out all passages. It's painful, but worked. (this is after installing a new impeller and cup, ensuring correct direction of impeller)
The upper hose connect always flushes strong, because the water bypasses the obstruction and gets right to the discharge.
I've had to troubleshoot with foot in trash can filled with water only.
I've had to remove the intake screens, remove thermostat, remove any brass hose fittings and coolant hoses. I blew compressed air, used weedeater string to chase out all passages. It's painful, but worked. (this is after installing a new impeller and cup, ensuring correct direction of impeller)
The upper hose connect always flushes strong, because the water bypasses the obstruction and gets right to the discharge.
I've had to troubleshoot with foot in trash can filled with water only.
Posted on 10/9/24 at 9:49 am to tigereye58
quote:
There’s a piece of metal in the shaft when I changed it and I replace that also.
The "key" is the piece of metal. The key fits in the slot on the shaft and the impellor has a similar slot that has to line up with the key/shaft slot. If you did not line those up, I think we found your problem.
Posted on 10/9/24 at 4:41 pm to Dock Holiday
Thanks. Yes those are definitely lined up.
I used YouTube to determine the direction of the impeller but I wonder if I installed it with the wrong rotation.
Do these things vary from model to model? That would certainly change the water flow.
I used YouTube to determine the direction of the impeller but I wonder if I installed it with the wrong rotation.
Do these things vary from model to model? That would certainly change the water flow.
Posted on 10/9/24 at 6:49 pm to tigereye58
You need to do some hard core Google work on how outboard engine cooling systems work so you can be thinking about how its supposed to work. Start at the bottom (impeller) and work your way up.
Don't take this the wrong way - if you dont know what a shaft key is, and can't figure out how to determine if there is water pressure in the power head, odds are you screwed something up working on it.
Don't take this the wrong way - if you dont know what a shaft key is, and can't figure out how to determine if there is water pressure in the power head, odds are you screwed something up working on it.
Posted on 10/9/24 at 6:52 pm to tigereye58
If you put the impeller in wrong it will still pump, it'll just wear out quickly.
Does it have water flow out of the prop? If it does, its pumping. Almost all of the discharge water flows out of the prop. How do you know it's getting hot?
Does it have water flow out of the prop? If it does, its pumping. Almost all of the discharge water flows out of the prop. How do you know it's getting hot?
Posted on 10/9/24 at 7:36 pm to DownshiftAndFloorIt
quote:
if you dont know what a shaft key is
Don't take this the wrong way - it's a woodruff key
Posted on 10/9/24 at 7:58 pm to DownshiftAndFloorIt
Ha. Nothing taken the wrong way. I’m a YouTube mechanic the whole way but I’ve managed to fix some crazy stuff using YouTube and no experience.
But that’s why I’m here. Admitting I’m an idiot and don’t fully understand the way everything works but willing to learn.
But I did change the woodruff key and aligned it properly with the impeller. That I am 100% sure of.
I know it’s over heating because the temperature sensor alarm goes off. I’m running it in a cow trough full of water not on muffs.
What’s odd to me is it was peeing when using the muffs but low pressure. I used the hose flush up top and got a hard stream. Then reversed it again to the muffs and got nothing this time. Reversed it again to hose up top and it peed again. Reversed to the muffs again and got a weak stream. Made me think there’s something in it that I can’t flush out. The original impeller was broken off in several places.
But that’s why I’m here. Admitting I’m an idiot and don’t fully understand the way everything works but willing to learn.
But I did change the woodruff key and aligned it properly with the impeller. That I am 100% sure of.
I know it’s over heating because the temperature sensor alarm goes off. I’m running it in a cow trough full of water not on muffs.
What’s odd to me is it was peeing when using the muffs but low pressure. I used the hose flush up top and got a hard stream. Then reversed it again to the muffs and got nothing this time. Reversed it again to hose up top and it peed again. Reversed to the muffs again and got a weak stream. Made me think there’s something in it that I can’t flush out. The original impeller was broken off in several places.
Posted on 10/9/24 at 8:05 pm to tigereye58
quote:
Made me think there’s something in it that I can’t flush out.
We used to have a john boat with a 25 hp mercury that dirt dobbers would go in the pee hole and build a nest. If the motor wasn't peeing. We had piece of coat hanger wire we would stick in there and break up the dried mud nest.
Posted on 10/9/24 at 8:16 pm to DownshiftAndFloorIt
Yes. Has plenty of water flow out of the prop from what I can tell when I use the muffs.
I definitely have dirt dobbers but can’t find anything showing that’s the reason. I clean them out of the motor housing all the time.
I definitely have dirt dobbers but can’t find anything showing that’s the reason. I clean them out of the motor housing all the time.
Posted on 10/9/24 at 8:59 pm to tigereye58
If it pisses on muffs and cools, but doesn't piss and overheats in a trough, it isnt pumping like it should. The reason it works on muffs is because the hose pressure is circulating water through the engine, not the pump.
If it was trash in the powerhead or the water tube it would probably still cool just fine at idle.
Usually there's a port somewhere on the engine you can screw a simple pressure gauge in to read water pressure in the block. That's what you really need to know. No pressure = pump problem. Pressure = engine problem.
If it was trash in the powerhead or the water tube it would probably still cool just fine at idle.
Usually there's a port somewhere on the engine you can screw a simple pressure gauge in to read water pressure in the block. That's what you really need to know. No pressure = pump problem. Pressure = engine problem.
Posted on 10/9/24 at 8:59 pm to weadjust
quote:
it's a woodruff key
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