Yamaha 150 HP, alarm- overheating or Oil?

[Blue Fish Bob]

I have a 150HP 2 stroke motor on 1994 Grady White. had the carbs cleaned out and ran it 6 times on Cape Cod few weeks ago and and it ran flawlessly. I brought it back to NY two weeks later and started it in my driveway with earmuffs on and I noticed no cooling pee stream and the alarm then sounded.

I turned the motor off and let it cool down, I then submerged the lower unit of engine in a 40 gallon container without earmuffs and tried it again, at first no pee stream then a weak one, followed by the alarm once more. I turned t he engine off again. I brought the boat to a Yamaha dealer, they replaced the water pump and tired it again the same result however- the alarm once again sounded with a weak pee stream.

The boat is still in the shop, they plan on removing the engine heads, they think there is blockage on the right side of the engine. Is this the next logical step? The thought is that there is blockage as a result of salt water scale and salt build-up. I noticed that there is a triagle above what I think is the oil gauge- it's the round circle that's almost entirely black? Could the alarm not be a result of overheating but rather with the oil delivery system? Both the aux. and main oil resevoirs are full, I did notice that after the carbs got cleaned that the boat seemed to use less oil- not sure if this is a cooincidence or not? Any help would be appreciated....

 

[richie rich]

Blue Fish Bob, first of all, great name....secondly, if she's not peeing you have a problem....when you first mentioned the alarm and no pee using ear muffs, that happens as sometimes you suck air in the muffs and don't have great pressure....I lost 2 impellers that way....Mr Grady told me to use FULL water pressure even though my Yamaha manual said not to...anyway, the impeller fried..melted right in the housing.

But since they changed it and don't feel its dead again, the blockage could be the correct move...been there as well....scale does build up over time especially if fresh water flushing was limited over the years. If both the oil tanks are full, its probably not the oil alarm....the light on the gauge should be clear to see whether its temp or oil...block the sun glare to see it better.....

 

[Blue Fish Bob]

Hey thanks for the feedback, I'm in even deeper now however. They pulled the heads and they were pretty clean no scale and only moderate carbon bulidup- but no blockage. The shop (Yamaha Dealer) is waiting for new gaskets and they are going to button her back up.

I am not sure what the next steps will be but my wallet is sure going to take a wallop, if any one has and ideas I sure could use the help?

 

[richie rich]

Bob, they opened it up and found nothing? Since they did exploratory surgery, see if you can negotiate a lower cost on that....if they went through the impeller, therms and anything else consumable like that and still found nothing off the head, something is really wrong with that picture.......did they repeat the warning buzzer or no pee scenario before opening up the engine? The blockage may be between the impeller and head area but you could verify that with a water hose and therms out of the head. I think J-I-T is a tech....maybe he can give you some pointers.

 

[gw204]

Thermostats and poppit valve. If your mechanic pulled the heads before checking those, find a new mechanic.

 

[JUST-IN-TIME]

well thats a good one

it could be
bad impeller housing
bad impeller exhaust rubber
bad t stats
bad poppet

the pee indicator, is just that, sometimes it pees good, other days no so go

never trust the indicator

i would have done something different

these shops got certifications?

 

[Tucker]

On these big Yamaha's the earmuffs don't always work. The only way to see if the cooling system is working is with a tank or put the boat in the water. I agree with these guys. If they didn't check the pump, poppet valve or stats; you got hacks working on the motor. Now I wonder if they are sharp enought to put the head bolts in the correct order and torque.