# Yamaha overheating problem



## natureboy3002 (Jan 2, 2011)

The last two trips out in the boat I've gotten an over heat alarm. For about five or ten seconds this accures while runing .I shut it down to an idle for a few seconds and the heat goes off. Could any tell me what my be causeing this problem.


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## BullyARed (Jun 19, 2010)

Does the water pump (impeller change last time?) work? Is there a steady water stream coming out from the peehole? If yes, it could be the temp sensor.


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## ATE_UP_FISHERMAN (Jun 25, 2004)

Check your popper valve. Use saltaway


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## fishnstringer (Oct 20, 2006)

*Are you saying,*

by using saltaway in line when running your engine on a hose, it will keep the pop-off valve, and I guess thermostats from corroding or salting up? That should makes sense to me, but for some reason it's hard to fathom that short of a period of running on a hose would overcome the time the engine is running while fishing.


ATE_UP_FISHERMAN said:


> Check your popper valve. Use saltaway


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## Capt. Billy (Mar 6, 2010)

My 2003 Yamaha 150 HPDI was doing the same thing and I had a stuck thermostat. There are two on each motor and they are easy to change. Fixed the problem.


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## Sonnysmarine (Mar 18, 2007)

The pressure releif valve could be sticking, it opnes as water pressure increases, to dump out the water of the block. Stays closed at lower prms to keep water in the block to allow time for the engine to absorb heat to take it way. The older poppet valves had a cross that fit into the block, and fit into a rubber grommet that salt would build up build up and squeeze the x piece and cause it stick. The new updated poppet valve on fits against the grommet and can not stick .
It's easy to check, but if the water pump has not been changed in a couple years, then it would be wise to replace, the vanes get and can not pump enough water to the block. Bad thermostats do not let cooling water flow around the out side of the heads water jacket area and causes over heating, but should see it over heating at idle for a while. The water on a hose is a lot cooler than the water in the bay right now.. a 20-30 deg inlet water temp can make a big difference.


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## natureboy3002 (Jan 2, 2011)

It has a new impeller kit it and it has a steady pee while running.Guess that sensor or could my prop be over ramp I think my prop my need recupped not sure how to tell. But will check the popper vavle. Is that wherenthe ear muffs go.


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## Sonnysmarine (Mar 18, 2007)

no it in the very back of the block on lower right had side, has a 1" hose that runs from it to the mid-section, two bolts, to remove it has a spring so remove carefully. What motor some are easyier to see. HPDI's you have to remove computers to get to,, may not be a job you want to try


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## alant (Dec 7, 2006)

My fishing buddy is having a similar problem with his 200hp Yamaha 2-stroke. We were out fishing and couldn't run at high rpms without the alarm sounding. We'd idle for 20 or 30 seconds and the alarm would go off. This seems like a very short time for it to cool if it was overheating. It ran fine at lower rpms. He's already replaced the water pump, thermostat, and poppet valve and is still having the problem. The pee stream seems fine. The water seemed just a little warm coming out the pee hole when the alarm sounded. Seems like it would have been warmer, or even hot. He's also tried salt-away and it didn't help. He was told salt away would help to prevent salt, but wouldn't open clogged passages - I'm not sure about this information. He's trying to bring it to the shop now to get another look. I'll post if he gets a resolution. Please do the same when you resolve your issue.


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## BullyARed (Jun 19, 2010)

You may use a thermal melting pencil and see it would melt at high RPM. If it melts, the mortor doesn't get enough water. If not, it could be the sensor. I had this similar problem on my 2-stroke Suzuki 50HP outboard and I isolated it to the thermal sensor even though I got a steady water stream from the peehole. The alarm just went off at high RPM and then the motor dropped to a low RPM and then the alarm stopped. You may want to check out the thermal sensor.


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## seahorse5 (May 27, 2007)

natureboy3002 said:


> The last two trips out in the boat I've gotten an over heat alarm.
> 
> Could any tell me what my be causeing this problem.


Could you tell us which particular motor you have ?


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## Tex-Cajun (Sep 14, 2010)

What year model are you running?? The thermostats are easy to check and/or replace.


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## alant (Dec 7, 2006)

My buddy finally had a chance to run his boat after replacing the thermal sensor. Seems that was the problem. No alarms at high rpms.


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## Captain Marty (Jul 14, 2006)

alant said:


> My buddy finally had a chance to run his boat after replacing the thermal sensor. Seems that was the problem. No alarms at high rpms.


 My Yamaha 200hp was having the same problem. At about 3700 rpm the alarm would come on. After $300 at a boat shop and after replacing the thermostats, water pump, poppet valve, I replaced one of the thermal sensors. Problem resolved.


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## leslie pohl (Aug 10, 2011)

*yamaha overheating*

I had the same problem last year with yamaha 150 trp. First changed out water pump impeller,thermostats and poppet valve. went fishing and same problem anything over 3200 rpms and 1/4 mile later alarm would go off so back to square one bought marine flush mild acid from hammerhead marine hooked up pump and circulated for 1 hr in contained loop then flushed for 30 minutes with water. Went back fishing and same problem but at a little higher rpm. So bought a set of head gaskets and water jacket gaskets aprox. 120.00 and pulled off heads and found the problem. There are small channels in heads for water to flow from block thru the heads and they were plugged up the flush had softened it up but most was still there.Cleaned up with small wire brush and screw driver and reinstalled. back fishing again and no more problems.:bounce:


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