2008 185 Sport Temp Alarm

[chopperwes]

My temp alarm is driving me crazy... anything over 3000RPMs it goes off then subsides when I go back to idle. My Mercury mech. has replaced the following ( not all at once): water pump and housing (old one did not have any missing pieces), thermostat, circulating pump and temp sensor. I can disconnect the sensor and the alarm goes away. We took it out on the water and used a temp gun to see what the real temps were and the temp gauge showed 175-180 but the gun showed 165 at the block and the risers were about 10 degrees difference between the two. can anyone help???? Thanks:smt100

 

[Bumble]

Does the temp rise over 3k when the alarm hits and goes down when you drop speed? If you are sure it isn't the over rev alarm as you disconnected the sensor and it went away, that is tricky. Does it matter on trim position? Stock exhaust? If the prop isn't engaged and you rev does it do that still or just under way? Last question...are all the drains sealed and tight? I'm thinking at higher rpm maybe there is air getting into the flow of water.

 

[blaster]

Was the circulating pump replaced or was the pump impeller in the lower unit replaced? If so check it again. Did you replace the sensor again? Are the hoses in good condition? Do you remember ingesting anything such as sand or plant material? How long has this been happening and did it change with the repairs?

The small difference in temperature between sides is normal.

 

[chopperwes]

the temp stays steady just above the 175 mark, I was about half way on the trim, I slow down and the alarm goes off. Do all the sensors share the same ground? I was thinking that unplugging this sensor I was taking the ground away from the rest of the sensors.... make sense? stock exhaust, my mechanic and I have gone over every connection. ( not to say we didn't miss something) thanks

 

[Lazy Daze]

Nothing clogging the intake?

On your t-stat housing, remove the two hoses at the "T" connector. Remove the ball/spring connector and inspect. Typically, problems with this will result in overtemp at idle, but not higher RPM... but it's worth a check. Stretch the spring out a bit and then reassemble.

If still having problems, let's verify that you are indeed getting good flow to the t-stat housing - especially before you start throwing more parts at it. With a cold engine, remove the intake hose and hold it into the bilge or a bucket. Start the engine and let it run for about 30 seconds. The water should be flowing out of the hose very smoothly and quickly.