1982 Johnson 50 Sea Horse - Constant Beep While Accelerating

Joined
Jan 17, 2019
Messages
902
Nope, runs perfectly fine at idle. It's not until I start accelerating past, say, 2000/2500 RPMs or so that the high-pitch ringing sound starts. It was very faint this time, almost inaudible. Changing the water pump seems to have helped a lot. It only overheats when under load at speed.
yep definitely check that those relief holes are spitting water after it warms up. with the IR gun, blip the throttle in neutral. you should see the temp sharply decrease. if you dont you know you have a restriction in the water tube grommet or exhaust seals as i mentioned (if theres no crack in the block or something but can easily check the plugs after a high speed shutdown to see if they are steam-cleaned).
 

cyclops222

Lieutenant Commander
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Mar 21, 2024
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Once cooling water gets above 145 to 160 F. Some minerals in the water start sticking to hotter metal parts. Basic chemistry.
Why us geezers used 130F Boat thermostats. Some salt water Commercial Clammers just removed the the thermostat. And reset the choke to be manual control. Spark plugs were cheaper. They ran at almost WOT all the time when not clamming. I still drive that way. Trolling or WOT.
 

Mc Tool

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Aug 7, 2024
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You stated on post 28 that those bolts were removed.

Which is it?
" I think there is one final bolt hidden underneath the trim tab holding up the LU"
Aint that hard to understand , sounds like OP believed with all his heart and soul , before God an all that , that he had found all the LU bolts only to later discover the one bolt remaining under the trim tab ( yep , the one numerous peeps miss the 1st lap round that ring of bolts );):)
 

Mc Tool

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LOL that is the plan!!!! Cannot get the LU off anyway because the bolt that holds the trim tab in is badly stripped / rounded. I think there is one final bolt hidden underneath the trim tab holding up the LU. The stripped bolt will need to be drilled out. Irwin extractor socket didn’t work. I just want to get this thing reassembled and run it. Maybe I’ll get an infrared thermometer to verify if it’s actually overheating.
Sometimes banging on the head of the bolt can sorta help shock them loose , and if you can get at it a bit of heat around where the bolt threads go into the mid section. If you can drill a piolet hole in the bolt head get a 3/8 or 7/16 ( I converted this to inches for you Trumpets :D ) drill and drill the head off , the idea being that if you can then remove the LU there will be a nice long bit of bolt sticking out for you to work with . :)
 

racerone

Supreme Mariner
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Dec 28, 2013
Messages
38,165
MC TOOL----See post #45------The 2 cylinder gearcase bolts are not the same as 3 and 4 cylinder models !
 

saltchuckmatt

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Jul 19, 2019
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" I think there is one final bolt hidden underneath the trim tab holding up the LU"
Aint that hard to understand , sounds like OP believed with all his heart and soul , before God an all that , that he had found all the LU bolts only to later discover the one bolt remaining under the trim tab ( yep , the one numerous peeps miss the 1st lap round that ring of bolts );):)
Nope, he later disclosed that he had removed the bolts but two of them broke off. Salt corroded broken bolts would have given us a clue that the driveshaft wasn't frozen in the powerhead.

Alls good with the OP so their really is no more reason to post here.
 

Elessar_94

Seaman
Joined
Nov 27, 2024
Messages
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Sometimes banging on the head of the bolt can sorta help shock them loose , and if you can get at it a bit of heat around where the bolt threads go into the mid section. If you can drill a piolet hole in the bolt head get a 3/8 or 7/16 ( I converted this to inches for you Trumpets :D ) drill and drill the head off , the idea being that if you can then remove the LU there will be a nice long bit of bolt sticking out for you to work with . :)
Luckily I was able to remove the trim tab bolt using an Irwin bolt extractor socket. They are designed for removing stripped/rounded bolts. Worked great, I had to destroy the trim tab to do this but the trim tab has since been replaced with a brand new one.

Also, turns out there was no hidden bolt underneath the trim tab holding up the LU. The only thing holding up the LU were the two snapped bolts. I brought the motor to an outboard repair shop and they used heat and wedges to get the LU off. That problem has been solved - and they put in a new water pump too 🙂

However, the original problem still persists: I am getting an overheat alarm at speed under load. I just ordered a new head gasket and will be taking a look inside the cylinder cooling channels to remove any salt buildup as that’s the next likely culprit.
 

Elessar_94

Seaman
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Nope, he later disclosed that he had removed the bolts but two of them broke off. Salt corroded broken bolts would have given us a clue that the driveshaft wasn't frozen in the powerhead.

Alls good with the OP so their really is no more reason to post here.
Correct, the only thing holding up the LU were the snapped bolts. Heat and wedges did the trick!

However, the initial problem still persists: I’m getting an overheat alarm at speed under load. It’s better now but not gone completely. I just ordered a new head gasket and will be replacing the old one / cleaning out the cylinder cooling channels next week. I’m thinking there may be salt buildup in there blocking the water flow.
 

Elessar_94

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MC TOOL----See post #45------The 2 cylinder gearcase bolts are not the same as 3 and 4 cylinder models !
You were right about this. There was NO hidden bolt underneath the trim tab. The trim tab bolt was load-bearing and needed to come out but it had snapped. I believe you were also correct about using heat + wedges to remove the snapped bolts. The repair shop did all that for me and replaced the water pump.

I’m changing the head gasket next week and cleaning out the cylinder cooling channels as I suspect a salt buildup is blocking the water flow as the reason we’re still getting an overheat alarm. The alarm isn’t as loud as it was prior to the new water pump/impeller, but it’s still ringing when I accelerate.
 

Crosbyman

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5,556
strange isn't.. you indicate the sound level of the alarm isn't as loud as it was before.
the heat sensor being a variable resistance & in theory proportional to the heat level being sensed..... seems to me the alarm itself should simply "kick in" and produce a constant sound level when a given current (temp) threshold is reached.

you checked/replaced the thermostat did you try a new alarm module ?

the module needs power to receive and properly process the sensor output . did you inspect all the wiring, connections voltage level supplied to the module itself. etc... ?

NOTE:
on some models they can the sensor a SWITCH... if yours should be direct ON -OFF device it may itself be defective producing a poor contact and end up supplying a " resistive" ground instead of a solid output hence a tone level less than what it should be.
 
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Grub54891

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Jun 17, 2012
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6,109
Had one at the shop that did that. It was the beeper itself that was shorted. New beeper solved the issue. I don’t actually know why it received the signal but it’s been fine since then.
 

racerone

Supreme Mariner
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38,165
Some beepers have a wee circuit in them,----When power is applied they do a " self check " and then turn off.----That little " circuit " can be defective.----The faint tone can also mean a poor connection or a wire touching ground somewhere.
 

Elessar_94

Seaman
Joined
Nov 27, 2024
Messages
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strange isn't.. you indicate the sound level of the alarm isn't as loud as it was before.
the heat sensor being a variable resistance & in theory proportional to the heat level being sensed..... seems to me the alarm itself should simply "kick in" and produce a constant sound level when a given current (temp) threshold is reached.

you checked/replaced the thermostat did you try a new alarm module ?

the module needs power to receive and properly process the sensor output . did you inspect all the wiring, connections voltage level supplied to the module itself. etc... ?

NOTE:
on some models they can the sensor a SWITCH... if yours should be direct ON -OFF device it may itself be defective producing a poor contact and end up supplying a " resistive" ground instead of a solid output hence a tone level less than what it should be.
I looked into getting a new temp sensor a while back but for this particular model (50hp, part# 0386686) they are quite expensive. I see one on eBay for $50 and it looks to be in worse condition than mine. That’s why I decided not to bother. But you bring up a good point, it is very strange how the sensor changes in volume. You can even hear how it changes in the video from my original post on page 1 (it gets noticeably louder towards the end of the video).

Here are some pics of the temp switch. I recently installed a WAGO as a quick disconnect and I thought that actually improved the connection a little. The wire strands looked fine and weren’t corroded any. I do think the engine is overheating still because it’s quite hot to the touch when it beeps. I promise I’m bringing an IR gun to the lake this weekend lol
 

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Elessar_94

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Some beepers have a wee circuit in them,----When power is applied they do a " self check " and then turn off.----That little " circuit " can be defective.----The faint tone can also mean a poor connection or a wire touching ground somewhere.
Roger that. This weekend I’ll scan the cylinder heads with a temp gun to confirm their temperature. Maybe it is just a faulty sensor, who knows. That would be an easy fix.
 

Elessar_94

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FYI - this clip is from this past weekend. Was testing the motor after the new water pump/impeller was installed. You can hear the high-pitch ringing noise coming from the motor. It’s very faint but it’s there.
 

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racerone

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???----Agreed , there is no alarm on the motor itself.-----Alarm buzzer is in the control box.----Clear communication is needed.
 

Elessar_94

Seaman
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I wonder what we’re hearing then :unsure:
It’s not a buzzer sound, it’s more of an extremely high pitch ringing noise, like a dog whistle. It is definitely coming from the motor, not the control box. I know it’s hard to hear in the video but we can both hear it on the boat. It’s a high pitch beeeeeeeeeep.

It starts when I begin accelerating and disappears when I slow down. It’s a bit more noticeable in this video, especially at the very end:
 

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