2001 mercury optimax 135 running hot

Faztbullet

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Mar 2, 2008
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As stated earlier probes not the problem as they are reading but cleaning wont hurt, might make em react faster. Check the seal behind poppet valve as problem is water pressure too low. Either a problem in impeller area (torqued to tight warping housing) or powerhead.
 

Sea Rider

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Next time removing the lower leg check the vertical water passage which delivers water upwards under the water pump's housing is free of salt layers which will reduce the amout of water intake being pumped upward thru the WP when at idle. If everytng checked is in excellent working order and this motor having worked in salt water for the past 21 years keeps doing same it's a firm candidate for a long descaler, desalting sesion...

Happy Boating
 
Joined
Jan 21, 2022
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As stated earlier probes not the problem as they are reading but cleaning wont hurt, might make em react faster. Check the seal behind poppet valve as problem is water pressure too low. Either a problem in impeller area (torqued to tight warping housing) or powerhead.
Thank you for your help.
Next time removing the lower leg check the vertical water passage which delivers water upwards under the water pump's housing is free of salt layers which will reduce the amout of water intake being pumped upward thru the WP when at idle. If everytng checked is in excellent working order and this motor having worked in salt water for the past 21 years keeps doing same it's a firm candidate for a long descaler, desalting sesion...

Happy Boating
Thank you, that’s what I think as well I googled and found barnacle Buster flush kit it will be here by Saturday so I will know more by Monday. Lower unit is clean under the lower water pump impeller housing.
 

Sea Rider

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That’s what I think as well. Lower unit is clean under the lower water pump impeller housing.
I'm not familiar with your motor, but all have an internal vertical water passage...

Lower Leg's Water Passage.JPG

Assume that have checked under the lower water pump's housing going downward that the tall water passage eding at the lower water intake screens is 100% free of salt layers, barnacle, marine growth, whatever already housed there over the boating years ?

Happy Boating
 
Joined
Jan 21, 2022
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I'm not familiar with your motor, but all have an internal vertical water passage...

View attachment 355076

Assume that have checked under the lower water pump's housing going downward that the tall water passage eding at the lower water intake screens is 100% free of salt layers, barnacle, marine growth, whatever already housed there over the boating years ?

Happy Boating
Yes sir all of that has been cleaned
 

racerone

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Dec 28, 2013
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36,047
Well----.5 PSI ( 1/2 PSI ) at idle means that you have a lousy gauge or something is wrong.-----You are sure the key is driving the impeller ?-----And are you using a factory impeller or some aftermarket good deal ?
 

vroom ZOOM

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Aug 15, 2017
Messages
369
IMHO 0.5 psi at idle could be OK. Ive had a few outboards, and at idle, they would have under 1 psi water pressure at idle. Not saying yours should be, but not necessarily a cause for concern. Opti has a large telltale because all the water that goes through the compressor exits out the telltale. The large telltale can also cause a fairly large water pressure drop.

What does this mean? This means that if you have water out the telltale, it does not mean it is going through the block. A lot of opti overheats were done because the owner saw the telltale and thought the motor was cooling ok. Again, telltale does not indicate the amount of water going through the block. The air compressor has a separate water supply directly from the pump, and the water from the compressor goes right to the telltale.

Also check the tube coming out of the water pump. Those sometimes get melted. I also recall reading somewhere about opti heads getting salted up and causing an overheat. i agree that it is time for some salt treatment flushing.
 
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