Mercury 2000 140 v6 over heating

[NO BULL]

Hi,I have a 2000 v6 140 over heating at low revs under load,the motor is happy to be on ear muffs running with water coming out the water pump indicator hole,also at idle in the water heading out a channel the guage sit's 1/4 on guage and running 2000rpm to 2800rpm the temperature guage goes up to just under the hot if pull throttle back to idle the guage comes down or opening the throttle to wot it comes down.Have replaced water pump base,housing and impeller with gasket's,2 120 thermostat's,temperture sender,and water pressure relief valve diaphragm as the old one has cracked.Now have ordered the seal and grommet that sit's in the side of the engine block,new poppet valve and spring and washer,the question i have is i have been told to cut a coil off the new spring to help with opening as less pressure is needed to open it but have been told the valve need's to close fully and open fully when needed and cutting the spring will cause over heating also.Anyone else got idea's has im getting stuck.

 

[1nebel0]

Re: Mercury 2000 140 v6 over heating

Be sure and put the rubber grommet back on top of the outside of the water pump...this keeps exhaust gasses out of the water pump..Not saying this is your problem but many people leave this off so let us know if you left it off....good luck...Steve

 

[Dukedog]

Re: Mercury 2000 140 v6 over heating

Don't "cut" anything. If they wanted a "weaker" spring it would come that way. Why 120 T-stats? Heat makes horsepower but has ta be controlled. Tha motor needs ta run between 140 and 170 degrees ta be at its best. Are you getting a warning buzzer? Do ya have a pressure gauge?............Tha poppet assy. can be a very finicky piece at times.............

 

[NO BULL]

Re: Mercury 2000 140 v6 over heating

Took the boat out for a test run with spare's and tools on board,running the motor at idle in gear the left head was 125 and the right was 124.5 and the guage was 1/4 and the water telltail was 77.9,at 1/2 on the guage the left head was 137.8 and the right was 137.3 and water telltail was 78.9 and last one with guage just below H the left head was 137.8 and the right was137.9 and the telltail water 79.9 so the guage goes up to hot with with a small temperture rise so thinking the wiring or the guage is faulty.In the test run changed the temperature sender on the water and the same reading were very close.

 

[NO BULL]

Re: Mercury 2000 140 v6 over heating

Don't "cut" anything. If they wanted a "weaker" spring it would come that way. Why 120 T-stats? Heat makes horsepower but has ta be controlled. Tha motor needs ta run between 140 and 170 degrees ta be at its best. Are you getting a warning buzzer? Do ya have a pressure gauge?............Tha poppet assy. can be a very finicky piece at times.............

Put 120 thermostats in getting it to run cooler,no warning buzzer went off but does work when earthed,no dont have a water pressure guage only temperature have put poppet valve assembly back together as normal just think the calibration is out on the temperature guage.Thanks Paul.

 

[Dukedog]

Re: Mercury 2000 140 v6 over heating

Glad ya figured it out. Almost all "factory" (especially tha METAL reading type) temp gauges are that way. That's why ya gotta rely on tha warning stuff and pressure gauge till ya get it figured out.......Still need tha 143's though imo.................

 

[NO BULL]

Re: Mercury 2000 140 v6 over heating

Are there different types of guage's that can be used for temperature local boat shops only have quicksilver or is a water pressure guage the way to go but have been told pressure guages just tell's you the water pump impellor is working not a over heating problem or should i put a temp guage in with numbers on the guage and do i need to replace the sender and guage as a complete unit.

Cheers Paul

 

[Dukedog]

Re: Mercury 2000 140 v6 over heating

Gauges are just a reference, something ta look at. You hafta know actual temps first before ya even consider believing tha gauge. What your seein' is typical with those types. Main thing is keepin' tha buzzer workin' right. Some add an LED light that comes on when tha buzzer is energized. Which is a very good idea. A big one.

Water pressure is way more important and anyone that's says not don't know squat about these motors. Think about what ya said, "just tells ya tha water pump is workin'"!!! If ya look at it it will tell ya your "gonna have a problem" long before ya do. It will tell ya all is good or not so good with tha whole coolin' system way before tha buzzer and/or temp gauge if ya pay attention to it. A strong stream can be very misleading. Tha pressure gauge "always" tells tha truth......jmo

 

[Faztbullet]

Re: Mercury 2000 140 v6 over heating

Water temp guages cause more "nonexistent" problems and chasing "ghosts" than they are worth, I will n ot sell a customer a temp guage. Always use a water pressure as its instant reading, tell condition and wear of pump and if it reads "0" run can shut it down way before a gauge reads hot!!!!