2000 mercury optimax 225hp overheating..

[robaloroger]

I changed out the impeller, thermostats. checked the strainer screen.I get a nice flow of water out of the pee hole. I am running the motor at around 2000 rpms for about 5 minutes before the alarm sounds. When I touch the heads the 2 middle cylinders #3 & #4 are very hot to the touch. The other 4 cylinders are barely hot. Compression on the motor is between 83-90 lbs with about 1100 hours. I was thinking about replacing the poppet valve but it is overheating at low rpms.
Thanks

 

[1nebel0]

Re: 2000 mercury optimax 225hp overheating..

The compression indicates plus your hours you are getting ready for a rebuilt...Poppet valve only comes into play around 2500 rpm when the motor needs to "dump" the hot water faster than when at lower rpm's...It this is a salt water used motor the water passages can be very likely blocked... One would have to take the exhaust plate off to see however with any corosion at all the bolts will snap...That is what happens to salt water motors. You have a blockage of some sort...You can take the therms out and try and back flush the system with the lower unit off however the exhaust plate is usually where the oil and gunk pile up causing restricitions...just my 2 cents......

 

[SparkieBoat]

Re: 2000 mercury optimax 225hp overheating..

yep you will need to rebuild soon..make sure your timing is right and that you are using the correct spark plugs...the back flush idea sounds like a good thing to do..drop the gear case so the trash doesnt get stuck in your water pump.