water pumping issues with Mercury 2003 40 hp 4 st with alarm sounding above 200rpm

[trinescape]

G'day guys i have a mercury 2003 40 hp 4 stroke efi big foot ,my problem started a few weeks ago when we went for a sail 200m from our marina the temp alarm went off when i checked the tell tale it was only just dribbling out.firstly i replaced my water impeller, which wasn't that worn then my mechanic said to replace the thermostat which i had never replaced in 7 years ,well it was caked in salt and crud even though i flush my motor every time we come back ,well at first the motor pumped fine at the marina once again we got 200 or so metres and off goes the alarm and the flow has reduced again went to see my mechanic again and he said to check if the pick up pipe was on top of the water pump properly it was, but he also told me to put the hose up the intake pipe and flush the motor out with the thermostat out and in, a little bit of debris came out but here i am again with little flow and the alarm ringing in my ears any ideas guys? your help is muchly appreciated cheers Andy

 

[FLATHEAD MAC]

Re: water pumping issues with Mercury 2003 40 hp 4 st with alarm sounding above 200

Did you "back blow" with the lu off with compressed air ? Could still be some debre between the thermostat and p
'pee hole" also might try wurking a piece of weed eater line up into pee hole while running to possibly break up the crud

good luck happy new year

 

[trinescape]

Re: water pumping issues with Mercury 2003 40 hp 4 st with alarm sounding above 200

Thanks FLATHEAD MAC i will give it a try and a happy new year to you to lets hope its a peaceful one world wide ! cheers Andy