Water not pumping Merc 50 HP 1987

[Gnich210]

Any thoughts on why I can't get water to pump? I just replaced the impeller and verified it is in the right way. I also have verified the tubes are clear. I am hooked to a water hose covering the vents on the lower unit and running at idle. The Motor is a Merc 50HP 187 Model Ser#0b299911. Any help would be greatly appreciated.

 

[eurolarva]

Re: Water not pumping Merc 50 HP 1987

Have you checked the thermostat? Might be stuck closed. If motor is not getting up to temp the tstat may not be opening. Is motor getting hot to the touch at idle?

 

[mcginleyc]

Re: Water not pumping Merc 50 HP 1987

You might have "piched" one of the gromets that connect on either end of the water pump tube when you were installing it. I would bet there is an obstruction somewhere. I bet is is near the adapter plate end of the water pump tube up near the bottome of the powerhead.

 

[Gnich210]

Re: Water not pumping Merc 50 HP 1987

I reverified and no obstructions.<br /><br />I checked and the motor is barely warm to the touch. I hadn't thought about the thermostat. I have been scared to run it very long even at idle. I will go ahead and replace the thermostat just in case. Speaking of, where is the thermostat located? I purchased a service manual from this site but it hasn't arrived yet.<br /><br />Thanks again for your help. This is a great forum.

 

[Keith Buchanan]

Re: Water not pumping Merc 50 HP 1987

Thermostat is located under port side manifold cover, if it's the engine I am thinking of there will be 18 bolts keeping it on, gently undo these, any that are a problem may need a little heat (DO NOT FORCE)..when all the bolts are out try to split the outer water jacket gasket leaving the inner exhaust gasket intact, dont worry if both gaskets split it's just gonna cost you more. And there it is that round thing that just fell out.<br /><br />When re-assembling use new gaskets, make sure everything is clean, put the three gaskets on dry, (third gasket being the L shaped gasket between outer cover and baffle plate), a little Loctite on the threads and torque outer 16 bolts to 150inch lb. Please find out torque settings for the two middle bolts as I cannot remember and definately do not overtighten..<br /><br />Best of luck Keith B...

 

[eurolarva]

Re: Water not pumping Merc 50 HP 1987

Thermostat on that motor I believe is a 110 degree one. IF motor is only warm to the touch you probably are not getting up to operating temperature. I dont know what area you are from but if outside temperatures are cool and you are running cold water on the muffs you may not achieve operating temperature at idle.

 

[65Fabuglass]

Re: Water not pumping Merc 50 HP 1987

if this the same model 50 horse merc that i have there is no thermostat. I have a restrictor on a water line on right side of the motor looking from the back at the very bottom if this restrictor is not there water will not come out at idle. if there is no restrictor there you can use a C clamp and tighten it till water comes out. found all this out when I had a very similar problem.

 

[Gnich210]

Re: Water not pumping Merc 50 HP 1987

Well thanks to to you guys i got it running. Seems the thermostat was stuck after all. I replaced it and it pumps water like a champ.<br /><br />Thanks for all the help.