alarm buzzers

[fish1]

i have a 1990 115 yamaha outboard and am have alarm troubles.problem started a while back the alarm may buzz today and not do it again for several fishing trips,i have changed both thermal switches,the complete oil resevoir tank,pump,oil level sensor,and i have changed the oil level sensor on the tank on the motor,when alarm goes off both are full,water is coming out of discharge in a strong stream,water is not hot,did again last night 1st time since i changed parts,what do i do next??

[Ken]

fish1,
Two more things to check:
1 - thermostats: can get mineral deposits on them and not open all the way - also, debris can get stuck in behind them and restrict water flow - remove and inspect - also, do a temp test on them to determine if they are opening up all the way - should be fully open at approx 140 degrees.
2 - pressure relief valve: the PRV may be sticking partially open due to mineral deposits or broken spring and allowing cooling water to bypass the water jackets and run out the relief holes - remove and inspect.
Good luck [img]smile.gif[/img] ,
Ken k

[Ken]

fish1,
To add to my previous post - the side discharge pee stream will not get hot because it is water coming from the pump that has not gone thru the water jackets - it is only an indication that the water pump is working, and really not a very good indicator of how strong/weak the pump is.
You may have a weak water pump - if it has been at least three years since last water pump repair, then it is about due, but I would try the other two things I mentioned first.
Ken K

[Pablo]

Hi Ken:
I have a 1993 130HP Yamaha on my boat that has been doing much the same thing with the alarms, the pump has been serviced (new) the thermostats (new) I have checked the Temperature probes and I get one to close at 180-Deg and the other at 210-Deg. according to the book the thermostats open at about 187-Deg so I am thinking the one p-robe is sending a premature signal and needs to be replaced, also where is the PRV located on my engine, That I have not checked.
What is the operating temperature for this engine?
Thanks
Pablo

[fish1]

ken,will temperature make all three indicators on my gauge light up and put engine into power reduction mode?

[Ken]

Pablo,
The thermo switches you are refering to are designed to close at around 185 degrees - when they close (continuity between the leads) this sends a signal to the ignition control (CDI) and to the console to indicate an overheat condition. The motor goes into rpm reduction mode, the horn (buzzer) sounds, and on some gauges, you get an overheat indicator to come on.
The thermostats are located in the top of each head assy - one in each. They are designed to be fully open at around 140 degrees.
I have personally experienced a thermo switch going bad and closing at 130 degrees, giving a false overheat alarm, but sounds like your thermo switches are ok. Since your water pump is new, I would suspect either bad PRV or thermostats (yes, even a new one could be bad, though not likely). You can pull the thermostats and do a heated water test on them fairly easy. Also inspect them for mineral buildup and for any debris that may have collected behind them restricting water flow.
The PRV is located near the bottom of the exhaust cover between the two head assemblies. It is under a dome shaped piece of aluminum housing that has a water hose about the size of your finger going to it. The PRV housing is held in place by two small bolts - remove it and you can get to the PRV (on some models, you may have to move the CDI over a little bit) - inspect it for mineral buildup and also the spring - also inspect the seat of the PRV to make sure it is smooth. The PRV is designed to open at around 20 psi to relieve over-pressure in the cooling system - but sometimes will stick partially open and allow cooling water to bypass the cooling jackets and out the relief holes.
As far as "operating temperature" for the motor, I would have to say around 135 degrees, since that is what the thermostats are designed to regulate at (they begin to open at around 125 and are fully open at around 140).
If you don't already have one, get yourself a Yamaha shop manual for your outboard - it explains all of the above - it will pay for itself .
Hope this helps [img]smile.gif[/img] ,
Ken K

[Ken]

fish1,
The overheat signal from the thermo switch goes to the CDI and to the console. The CDI puts the motor into rpm reduction by cutting back on the spark - that's why the outboard shakes like heck when this happens, because it is missing very badly.
The signal that goes to the console goes to the digital tach on my 2000 C115 and to the horn (buzzer), I believe. The signal to the buzzer may come from the CDI - not sure - but it is still initiated by the thermo switch.
Now, I do not know if the overheat condition would light up all three indicators on your particular gauge - Yamaha has made many different models of the digital gauge - but it will definitely put your motor into rpm reduction.
Get yourself a Yamaha shop manual for your motor if you don't already have one - will pay for itself many times over.
Hope this helps [img]smile.gif[/img] ,
Ken K

[Mike E]

Is the alarm going off at full throttle or or at idle? Is it a solid horn?

[fish1]

sometimes alarm comes on when i am at full throttle,sometimes when getting up on plane,last time i had made about a 15 min run i had throttled down to stop a hole to fish just before it turned off key it went off,it was at idle that time,alarm is consistant one it starts it want cut off,last trip made it back to landing loaded pulled out of water and it cut off

[Ken]

fish1,
Are you saying that the alarm is staying on sometimes after you turn the ignition key off ?
Ken K

[fish1]

no,sorry i didn't word correctly,what i meant was that while i was loadingthe boat the buuzers where going off,i cut switch off pulled out of water and after i got thru tying down i cut the switch back on just to see if they were still buzzing but they had stopped
thanks

[fish1]

ken,i am going to try those test you recommended earlier w/ thermostat and prv,mo local marine dealer does not have replacement gaskets in stock,any problem using a good permatex form a gasket,if used sparingly?

[Ken]

fish1,
You might want to check out parts availability with boats.net (sponsor of this forum) next time - they have good prices and reasonable shipping charges.
In the meantime, I would try to get by with the old thermostat cover gaskets. I just recently pulled the thermostats out of my fishing buddie's 95 C115 and we reused the old gaskets.
Since your outboard is older, the gaskets are going to be a little harder to save - but worth a try since you don't have new ones.
Try using a putty knife and gently work the knife between the gasket and cover, or between the gasket and head assy, whichever it looks like the gasket is turning loose of the most.
On my buddie's 115, I just put a thin film of grease (Mobil 1 synthetic) on the gasket surface before reinstall of the covers. You can use Permatex, but make sure it is the non-hardening type. And get those new gaskets on order - because there is a good chance you will have to remove the covers again in a few years, maybe sooner .
Good luck, and let us know how you come out [img]smile.gif[/img] .
Ken K

[fish1]

recieved new thermostats and also a new oil control unit(thought i might as well replace since i replaced evrything else)today from boats.net,they have the prv on backorder,put parts in today going afterwork tomorrow to see what happens hope this is a fix
thanks for all your help and suggestions,fish1

[Mike E]

Just take the Pressure Relief valve out and clean it. No parts to wear out.

Senkoboy