93 yamaha alarm sounding

[sunpacman]

My port engine is sounding the alarm and the temp. light is blinking. Engine drops RPM as expected when this happens. Not sure what is causing problem. The engine does not appear to be hot and does not happen everytime I take boat out. Also, after turning key off and waiting just a few minute (3-15minute),engine restarts and runs just fine for hours. Next time I go out...alarm within first 30 minutes and sometimes...no alarm at all? What gives?Not sure were to look first as it does not happen everytime I go out..HELP

 

[rodbolt]

Re: 93 yamaha alarm sounding

when was the last cooling system tune up?

 

[deejaycee_2000]

Re: 93 yamaha alarm sounding

Sounds like an oil problem ..... what HP is the motor?

 

[rodbolt]

Re: 93 yamaha alarm sounding

does not sound like any oiling issue I ever saw.<br /> sounds like a cooling system problem or possibly a temp swith is failing.<br /> only way to check is with a melt stick or temp gun,

 

[sunpacman]

Re: 93 yamaha alarm sounding

The engine has had the water pump replaced last season. Thats all that been done. The engine does not appear to be hot when the alarm sounds. I am gaging this on the fact that the engine restarts easily when the alarm is sounding. How do I test?

 

[sunpacman]

Re: 93 yamaha alarm sounding

oh, its a 200hp yamiha

 

[rodbolt]

Re: 93 yamaha alarm sounding

ya have to use a melt stick or a temp gun. once you verify engine temp at the head area that the temp switches are located we can figgure oout whats going on.<br />ease of restart is NOT an indicator unless you just run it so hot the pistons stick.

 

[sunpacman]

Re: 93 yamaha alarm sounding

Where might I buy a melt stick or will those inexpensive (50.00) temp. guns work?

 

[sunpacman]

Re: 93 yamaha alarm sounding

Where would I find the temp switches on a 93 yami 200hp. I'm going to get pricing on them and probably just replace. i feel confident the engine is not hot when the alarm is sounding. <br />Thank you

 

[rodbolt]

Re: 93 yamaha alarm sounding

it only costs pistons if your wrong, the switches are in the head with the pink and black wires on them.<br />they can be tested easily on the stove with hot water,a multimeter and a candy thermometer.

 

[sunpacman]

Re: 93 yamaha alarm sounding

I jsut dont no how to fix when the alarm and overheating sign do not happen everytime I go out. Was out today for several hours with no warning issues. What temp am I looking for with the candy thermometer? I assume that what its used for while testing.

 

[rodbolt]

Re: 93 yamaha alarm sounding

the switch closes at about 185*F.<br />I buy my meltsticks at ron's marine in portsmouth VA. if a 175* stick melts its overheated. its rare the switch's fail but it does happen. more likly its getting hot.

 

[sunpacman]

Re: 93 yamaha alarm sounding

thanks Rod. I'll take your advice again as it has been helpful to me in the past.I'll buy the meltstick and give it a go..update to this post will follow.

 

[rodbolt]

Re: 93 yamaha alarm sounding

break off a chunk and tape a piece to each head, if it ever melts you know it then. that meltstick is very similar to a crayon.

 

[sunpacman]

Re: 93 yamaha alarm sounding

UPDATE:<br />I was able to check the temp. with a temp. gun. Warmed engine for 30 minutes at idle...no alrm. Temp variable....high was 129. Never higher in idle. Alarn never went off.<br /><br />Drove the boat at 4800 + rpm's and finally temp light and alarm. Was not able to ck temp....turned key off to that engine and watched light that remained on for approx 1.5 minutes. Light then turned off and procedeed to restart engine....alarm was off. Again drove engine for 15-20 minutes on plain before alrm sounded again. Turned off again and light went out after less than 1 min. Restarted engine agian and of course no alrm. This hapened 2 more times before I was an no wake zone for the remained 3 mile ride and had no alarm the rest of the way.<br /><br />Any ideas? <br /><br />Also, PSI guage on that engine has always shown low PSI but has been that way since the impeller was changed last summer..<br /><br />HELP

 

[sunpacman]

Re: 93 yamaha alarm sounding

UPDATE:

 

[rodbolt]

Re: 93 yamaha alarm sounding

why could you not immediatly check the temp after the alarm? its only a matter of popping the hood.<br /> you only get so many chances at overheat before a piston lets go.

 

[sunpacman]

Re: 93 yamaha alarm sounding

Robo,<br />I forgot the temp gun in my truck. It would not sound again when I got back to the ramp. Should it cool that quikly? After shutting engine down and taking key out, light goes out in <br />40 seconds-1 min. Then continues running for 15-20 minutes before alrarm again.

 

[rodbolt]

Re: 93 yamaha alarm sounding

it almost sounds like scale is built up under the pocket the temp sensor sits in. its a blind passage.<br /> usually if the motor was actually above 180* it takes a few minutes to cool it.<br /> try it again and dont forget your temp gun. make readings from the block and area around the sparkplugs and the temp senders.<br /> if its hot they should all pretty much agree. if its scale they wont.

 

[sunpacman]

Re: 93 yamaha alarm sounding

I'm going to go forward with the waterpump replacement. Since I'm showing low PSi on the guage, I'm guessing its not a bad idea to check. I'll update once complete and tested.