Mecury BlackMax 175Hp, Constant Beep and Overheating

[Robertse]

Hi, I Mecury BlackMax 175Hp, which Constant Beep and Overheating. I have replaced the impeller water pump, it has a strong pee (pumps water strongly), howver the water coming out of the pee hole is very hot. All help will be respected. Thanks in advance.

 

[racerone]

Blown head gasket can cause overheating.

 

[Dukedog]

do you have a water pressure gauge?... if so need readings at idle, mid range and wfo.........

 

[Chris1956]

Did you replace the thermostats? Rebuild the poppit valve?

A hot telltale is a sign on a lot of motors, that the thermostats are not working properly, or the cooling passages have a blockage.

 

[Faztbullet]

What year?

 

[Dukedog]

when ya guessin' with an over heat problem and no pressure guage... replace "complete water pump"(not jus impeller), poppit kit and replace both t-stats... its relatively cheap maintenace anyway... then install a guage....... jmo.

 

[Njsloans1]

My 150hp Saltwater was doing that. I changed the impeller, 2 thermostats and poppet valve. My thermostats were completely corroded and blocking the passage ways. Problem solved.

 

[Robertse]

Blown head gasket can cause overheating.

Thanks for the repy. The compression test come in at about 115-120psi, which is good, the head gasket is fine, no breaks or leaks.

 

[Robertse]

My 150hp Saltwater was doing that. I changed the impeller, 2 thermostats and poppet valve. My thermostats were completely corroded and blocking the passage ways. Problem solved.

Thanks, I have the Thermostats which seems fine, but I will replace them. Then the poppet valve.

 

[Robertse]

do you have a water pressure gauge?... if so need readings at idle, mid range and wfo.........

Sorry, I don't hwave a water presure gauge.

 

[Robertse]

What year?

1989

 

[Robertse]

Thanks, I have check the Thermostats which seems fine, the open when heated, I also flushed engine via the Thermastats holes when I took them out. It was clean. However I have just ordered new Thermastats and eplace them. Then if there issue is still there I will also replace the poppet valve.

 

[Robertse]

1989

Thanks, I have the Thermostats which seems fine, but I will replace them. Then the poppet valve.

Thanks for your reply. I have checked the Themostats which are fine and clean, the open up in a pot of boiling water, I still ordered new Themostats, but for the time being, I removed the Themostats and run the engine, it still runs hot, the alarm is going off

 

[Chris1956]

Those motors are not made to run without thermostats.

Is the poppit valve working properly? It should open at about 2000RPM and allow a whole lot more cooling water thru the block.

Put a torque wrench on the head bolts and check 'em for tightness. Sometimes they can get loose and allow compression to leak into the cooling system causing overheat.

 

[Robertse]

Thanks Chris, Note I will not run the motor without the Thermostats. I hope I didn't damage the engine as I ran it for about 30 minutes without the Thermostats... I have already torque the head bolts to 30 lb. ft. (40.5 N·m) then turn an additional 90°.