posted 05-31-2003 02:34 PM ET (US)        

A few months back I posted a question concerning causes that triggered the overheating alarm on my 1989 Yamaha 200. I received a lot of assistance as to possible causes and remedies to the problem, including a defective water pump and thermostat as the primary culprits. My nephew replaced the water pump and thermostats for me. Last weekend we started up the engine on its trailer. Unfortunately, the telltale water stream was still weak. The stream strengthened slightly when I gave the engine more fuel. However, after a few seconds, the telltale stream stopped altogether. We shut down the motor, and my heart dropped. It seems that a blockage has occurred somewhere in water-cooling system. I have to admit that it appears that my worst fear has happened, that corrosion has finally taken its toll on the motor. I also have to admit that I was not prudent in flushing out the motor after every use; the boat was used only in the ocean. The boat has also been moored in a slip for the 14.5 years that I have owned her, except for haul outs to apply new bottom paint and other out-of-the-water maintenance work.

We are making arrangement to take the boat to a Yamaha mechanic. Does anyone have a suggestion(s) as to what can be done, or should be done, to determine the cause of the blockage? Even more important, is there anything that can be done to clear the waterways; if it is determined that corrosion is the problem. I知 not aware of products or methods to remove blockages or clear blocked waterways. I知 sure the mechanic will also look into the possibility that my nephew did not install the pump or thermostats correctly. My nephew is familiar with boats and outboard motors; he owned a Montauk and replaced the pump and thermostats on his boat. He also had a Yamaha Maintenance Manual to guide him. However, my nephew is not a seasoned mechanic, at least he does not make a living as a mechanic.

If the worst-case scenario comes to pass, and the waterways cannot be cleared. What are my options? I certainly cannot afford to buy a new motor at this time. I believe a new four-stroke Yamaha runs around $16-17 K. I知 not familiar with outboard motor cooling systems. I guess, depending if we can determine where the blockage is located (in the heads or block), that I can replace the affected part of the engine. However, due to the age of the engine, replacement parts may not be available.

Well, I think I have written enough. I await your comments with a heavy heart LOL.

Regards,

posted 05-31-2003 04:17 PM ET (US)            

A friend of mine went throught the same excersize that you are with nearly the same vintage and identical horsepower Yamaha. His is on an Outrage moored at Long Beach, CA.

On tear down it was found that his cylinder walls had corroded through into the exhaust chambers. That powerhead was finished.

He ended up having the powerhead replaced and it was about $4,500.00 parts and labor. Not bad for California.

posted 06-03-2003 11:14 AM ET (US)            

By the way, even though the telltale does not pee, is there water coming out from the lower unit? that is where the bulk of the water will exit during running. You can tell if it feels warm.

posted 06-05-2003 10:36 PM ET (US)            

Thanks for the advice. We did check the tube between the block and the outlet orifice. The hose checked out OK. We were also getting good water flow from the exhaust hub. I have not yet heard from my nephew, we are having problems finding a mechanic that will be able to look at the engine. The waiting time right now is 3-4 weeks. In the interim, my nephew and I may fool around with the motor some more, taking into consideration all of your suggestions.

Thanks again,

posted 06-11-2003 01:02 AM ET (US)            

Regards,

posted 06-18-2003 02:35 AM ET (US)            

Good news: The cause of the non-existent tell-tail stream was solved. It turned out that an "O" ring somewhere along the path of the water intake system (at the lower end I believe) had caused the blockage. The stream now is as strong as an 21 year old after a six-pack of beers!

Bad news: After launching the boat, the alarm came on again about halfway (5 minutes) to my slip.

So, one problem solved, but the original one still lingers. I do remember that one readers suggestions as to the cause of the problem did not concern the cooling system, but rather problems in the fuel system. This reader suggested that I check the primer bulb. Apparently, if air works its way into the fuel system, the alarm is triggered, or something along those lines. This specific possibility was not an issue in that I had replaced the primer bulb. However, for a while now I have notices fuel odors near the rear sump. At first I thought it was the result of all of the work that we had been doing in the motor and fuel line area. I replaced the fuel lines a while back. However, when I looked closer, I noticed a fuel leak at a coupling where the fuel line passes through the wood sump haatch. I thought to myself, could this be the problem. After replacing the coupling, and determining that the fuel leak had been mitigated, I decided to start and run the engine to see if the alarm would activate. To my surprise, the alarm did not come on after about 10 minutes of running the motor slightly above idle. I then put the motor in gear for another 5 minutes, and the alarm still did not go off. Unfortunately, I did not have time to take the boat for a cruise, the real test. So, at this time I really do not know for sure if the alarm problem had actually been solved. I知 hoping to get some time to take the boat on a sea trial this weekend to see what happens. I知 also going to try and get hold of an infrared temperature gage or some low-tech temperature crayons to make sure the motor is not overheating before I take her for a spin.

One reader asked about me about the condition of the 2-cycle oil system. I checked the oil reservoir, and it is full. No one yet has mentioned the possibility of a faulty oil injector unit (I知 not sure of the proper terminology since I知 not that knowledgeable about motors) as a possible problem. I will look into that possibility as well.

I値l keep all of you informed.

Thanks for all of your impute,

posted 07-05-2003 12:33 PM ET (US)            

I wanted to let everyone know that it appears that my alarm problem has been resolved. Following is a recap of my ordeal:

ｷAbout a year ago I posted my alarm problem on this web site.
ｷI received quite a few responses with various opinions as to the cause of the alarm-sounding problem, most of which centered around the cooling system.
ｷI eventually, with the help of my nephew, replaced the impellors and thermostats.
ｷWhen performing an out-of-water test the telltale stream was a dribble then eventually stopped altogether.
ｷI had a mechanic look at my motor and he found that an O-ring had deteriorated an had become an obstruction,
ｷI ran a test on the motor again, and the tell-tail-stream was strong.
ｷI launched the boat and half way to my slip, the alarm sounded @#$%&!@#@$^%$!!!!!!
ｷI went back and reviewed all of the opinions and suggestions that were offered to me on the alrm problem. A couple of suggestions concerned leakage in the fuel system, resulting in air infiltration that could trigger the alarm.
ｷI inspected all of the fuel lines and fittings of the fuel system, and I found a crack in one of the fittings below the cockpit deck.
ｷAfter replacing the fitting I ran the engine in my slip for 30 minutes without the sounding of the alarm. I did not have time to taker her on a sea trial until the following weekend,
ｷThe following weekend I ran the motor at the dock in neutral and in gear for another 30 minutes with no alarm. I finally took a one-hour harbor cruse without incident.

So, it appears that my alarm problem has been solved. It would be difficult to conclude that the leaking fuel line was the sole culprit for the sounding of the alarm because replacement of the impeller and thermostats were well over due. In addition, the leak at the fitting was hidden but obvious, so why did I not notice this condition earlier is a mystery. I did notice a considerable loss in fuel when I looked at my fuel gauge recently, but since the boat sat unused for nearly a year, I had no reason to look at the gage. None-the-less, I cannot ignore the fact that even after replacing the impeller, thermostats and O-ring that the alarm still sounded. So, I have concluded that the fuel leak was definitely a problem, but that the other engine components also were also likely contributors to the sounding of the alarm.

I think that one thing is for certain, that this site was very helpful in the resolution of my problem. If it were not for the two gentlemen who痴 fuel line diagnosis had not been mentioned, I would still be scratching my head. I suppose during this entire process would have been shortened if I had broken down and had taken my boat to a mechanic. But, that痴 water under the bridge now.

Anyway, thanks for all of you that had made suggestions.

Regards,