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Old 01-27-2009
mcatan2468
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Default Pressure Control Valve and Overheating

I had problem with 2000 - 90 yamaha 2stroke overheating as soon as I ran it up to 4000 rpm..... finally ended up replacing the thermostat and pressure control valve. I noticed that the Pressure Control Valve that I took off looks different from the new replacement . Is this an improved design? This finally fixed the problem that stumped the mechanic. He had replaced impeller and took apart the water jacket costing me $. I replaced the thermostat and pcv myself from advice on this forum and the motor runs great now.
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Old 01-27-2009
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Good job! Glad to hear you got it. They did change the PCV, the new ones don't stick open as bad.
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Old 01-27-2009
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Default Do I have a potential cooling problem

I have a 1994 225 hp 2 stroke that was put in service last season after being idel for approximately 10 years. A marina did replaced the water pump.
I have notices that when the engine runs at idle the pilot stream is very weak and only improves at engine speeds above 1800 rpm or after warming up (but only on an intermittant basis). I do not know how the engine was cared for prior to my ownership but it does run very well and does not overheat.

Is there as possible problem with the thermostate and/or pressure control valve?
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Old 01-28-2009
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If the thermostats and pressure control valve wasn't check when water pump was replaced then they do need to be checked.
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Old 01-28-2009
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Thanks for the heads up.
Is this the possible reason the pilot stream is week and only intermittently better as the engine warms up?
I don't believe the marina checked the thermostats and pressure control valve so I will do as soon as the snow clears. I assume this is a straight forward job but are there any hidden issues? I may as well just replace these parts.
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Old 01-28-2009
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It's hard to say, what you call weak and what I call weak may not be same. Water pressure will increase as rpm's increase because water pump is spinning faster. If not overheating then probably ok.
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Old 01-28-2009
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Just comparing to my older 84 Johnson 70 and 2004 Honda 15 hp kicker (both at idle) it seems very weak. I've also noted better flow from other Yamaha 225's at the boat ramp.
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Old 01-30-2009
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Quote:
Originally Posted by boats.net View Post
Good job! Glad to hear you got it. They did change the PCV, the new ones don't stick open as bad.
Is it possible for the same sort of problem to happen with a 115 ? i see in the manual the pcv is in the rear cover !
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Old 01-30-2009
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Yes if the pressure control valve sticks open there will be a loss of water pressure.
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