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gsmith131

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"Hi ,I have a 88' 150 blac

"Hi ,I have a 88' 150 blackmax,new water pump with good stream from telltale. the other day started to overheat out of nowhere,thermostats were also replaced before season,the higher the rpms the faster it gets hot(obviously) but when i knock the throttle down temp lightens up while still going.took thermostats out and ran without and still have same problem.any ideas would be great(im afraid to ask) like i said ,intakes seem clear being i have a good stream for discharge. thanks"
 
"George, did you replace the p

"George, did you replace the poppit valve?

The thermostats work from idle to somewhere in the 1500-2000 rpm range, then they are pretty much bypassed in favour of the poppet valve.

It may be stuck/shot/corroded/broken etc..."
 
"thanks graham,so as to not pl

"thanks graham,so as to not play around i replaced the poppit and thermostats and checked all lines for blockage.problem has not gone away,so boat is now out of the water and i checked out waterpump,seems to be good,(new at beginning of year).when i am at trolling speed,temp is midway,as soon i start to throttle up,temp rises along with rpms.motor seems to be running smooth.Any more ideas ,i am at a loss at this point."
 
"just to add when i tried to f

"just to add when i tried to flush with ear flaps i am getting no water from the tell,when i start motor i am getting small stream.I had lower unit off before to check pump and i could see intakes were clear and pump was clear,and when i put hose to fill tube i got water out of tell."
 
"Ok then, you need to confirm

"Ok then, you need to confirm that the temp is actually getting up there at the same rate your gauge is rising.

The temp sensor is a pretty cheaply built component - so while the temp is probably rising, the sensor may be making it look worse than it actually is.

The thermostats are set for somewhere around 140 degrees (143 exactly I think), that is considered "operating" temperature.

The poppet takes over after about 2000 rpms or so and the temp may well rise as high as 170 and that would still be "normal".

190 is considered "hot" and the point where an alarm would go off.

The sensor works on simple resistance and it may be on it's way out.

If you know someone with one of those infra-red tempurature guns you can take a remote reading, at 50 bucks or so for a sensor it's not something you simply want to swap to check although, I believe these can be tested with a pot of water on the stove a thermometer and a ohm meter - can dig out the method/specs if it is something you are interested in testing yourself..."
 
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