C150txrx

[TOMWIZ119]

Sea trialed '99 C150TXRX. Ran like a bat outa hell BUT at the dock in idle the overheat alarm went off and gauge went high. Owner rep says it is not getting enough water so put shifter in neutral bypass and increased speed. Temp dropped and alarm shut off. Owner rep says idle is set too low. Engine just had water pump and thermostats replaced with good in-tank report. Feeling leery - any advice?

[panasonic]

Tach on the boat? What was the idle speed. I would think that the Water pump would be able to put enough water through the engine to keep it cool even if idle is too low...
How do you know Water pump was actually replaced? Was it peeing alright when at idle?

[bc545571443]

Not positive if that model has it, but if he replaced all that he said he did it could be the poppet valve.

[Jason2tpa]

Sea trialed '99 C150TXRX. Ran like a bat outa hell BUT at the dock in idle the overheat alarm went off and gauge went high. Owner rep says it is not getting enough water so put shifter in neutral bypass and increased speed. Temp dropped and alarm shut off. Owner rep says idle is set too low. Engine just had water pump and thermostats replaced with good in-tank report. Feeling leery - any advice?

Sure do. Grab a phillips head screwdriver. Get back out on the boat, allow engine to warm up to normal op temp. Turn engine off. Remove the upper cowling. Turn engine on. Take your handy dandy phillips driver and stick it in the head of the idle speed adjustment screw (located on the middle carb). Make a 1/8 turn clockwise. You'll hear the idle speed increase. Make this adjustment until rpms are within spec (700 +/- 25). Wait for overheat alarm to activate. If no alarm, the owner wasn't pulling your leg (though his laziness for not fixing this before you sea trialed is perplexing). If it does alarm, the owner is full of crap. Which at that point, everything the owner has told you about the engine becomes suspect.

[Jason2tpa]

Sea trialed '99 C150TXRX. Ran like a bat outa hell BUT at the dock in idle the overheat alarm went off and gauge went high. Owner rep says it is not getting enough water so put shifter in neutral bypass and increased speed. Temp dropped and alarm shut off. Owner rep says idle is set too low. Engine just had water pump and thermostats replaced with good in-tank report. Feeling leery - any advice?

Sure do. Grab a phillips head screwdriver. Get back out on the boat, allow engine to warm up to normal op temp. Turn engine off. Remove the upper cowling. Turn engine on. Take your handy dandy phillips driver and stick it in the head of the idle speed adjustment screw (located on the middle carb). Make a 1/8 turn clockwise. You'll hear the idle speed increase. Make this adjustment until rpms are within spec (700 +/- 25). Wait for overheat alarm to activate. If no alarm, the owner wasn't pulling your leg (though his laziness for not fixing this before you sea trialed is perplexing). If it does alarm, the owner is full of crap. Which at that point, everything the owner has told you about the engine becomes suspect.

OR

With the engine on and in neutral and overheat alarm activated....perform all of the above, but continue to turn the idle speed screw clockwise until the alarm cuts off. Note the rpms that caused the overheat alarm to cut off. If the rpms you noted that caused the alarm to cut off are over spec (>725 rpms), this would imply a cooling system issue.

Disclaimer: the 2nd method is probably a little shaky since you don't know how much time is needed for the engine to cool down after each incremental idle speed adjustment. Needless to say, the engine is overheating as you wait to see if the adjustment made causes the the alarm to cut off. And the engine should never be run when the high temp alarm is activated. Just saying.

[TOMWIZ119]

C150xtrx overheating

Fyi: actually talked to the shop that did work on engine. Saw the repair bill for new water pump and thermostat. Could see t-stat was worked on. Engine did pee both in shop tank and on the water. Like the idea of making idle adjustment since all it took was a nudge on the shifter to increase the speed and then the temp dropped and alarm went off. No problem at higher speeds on the water just at the dock. Admit that am skeptical since I believe that it shouldn't take much water to keep an idling engine cool.
Thanks for the come backs.

[rodbolt17]

I call total BS .
how many shots ya got at overheating till it wipes a piston.

I say fix the issue.
if it all is well you can idle that motor down until it dies and it stays cool.

most likely the pressure control valve or the damper seal under the impeller plate.

have a master Yamaha tech inspect it.

I have a 5.7 Volvo in the shop apart now.
the guy bought it 3 weeks ago and a week ago a local monkey put a head on the stbd side, the port bank had water in all 4 when I got it.
owner says he had a mokanik look it over in FL.
that motor was junk when the mechanic in FL looked at it.
incompetence or crooked.

had I inspected it the man would NOT have a 14,000 dollar boat that needs 8,000 dollars of long block work.

find a competent tech to look at it.

[TOMWIZ119]

the final solution

Rodbolt had the best advice AND I listened to my gut - cancelled the deal to buy the Cobia with the overheating engine. Really wanted the boat but didn't want to play shop roulette with the overheating and possible damage. Thanks for the input but there are always other boats and afterall the engine is the most important part.