Merc 500 water pump problems

[TominatorNY]

I have a 1970 Merc 500 50 hp, water pump only pumps much water when you rev the idle. Dropped the lower unit, cleaned pump, looks good, outlet tubes are not blocked, still pumps little water. Dropped lower unit again, hooked garden hose to the tube that carries water up into the motor. Still not much water going thru the engine, most of it returns down into the lower unit around the exhaust outlet. Could the tube from the pump to the powerhead be disconnected up at the base of the powerhead? How do I access this area? Do I have to pull of the whole powerhead?

 

[mellowyellow]

Re: Merc 500 water pump problems

welcome aboard,<br />try some compressed air into the tell-tale.<br />critters love to build nests in that lil' hole.<br />good luck,<br />M.Y.

 

[TominatorNY]

Re: Merc 500 water pump problems

Pee hole is not plugged, cleaned the tube with a wire up to where it comes out of the motor.

 

[mellowyellow]

Re: Merc 500 water pump problems

hmmmmm... how old is impeller?

 

[tinyjcboater]

Re: Merc 500 water pump problems

where do you fish in syracuse? have any good spots? new to the area

 

[TominatorNY]

Re: Merc 500 water pump problems

Hey Tiny, email me at teb1@cornell.edu and I'll give you some fishing info!<br /><br />

Originally posted by tinyjcboater:<br /> where do you fish in syracuse? have any good spots? new to the area

 

[ehenry]

Re: Merc 500 water pump problems

That model engine has a stainless insert in the water pump housing. If your impeller is new...could be that the insert in the housing needs replacing.

 

[bfast1fishing]

Re: Merc 500 water pump problems

I asked a similar question on Sat about my V150. The reply from Kclost was to check the poppet valve {relief valve} located on the starbord side down low under the switchboxes. I checked that and it is definitely bad. If stuck open it allowes the water to dump into the exhaust housing, apparently that should only open at high RPM's. May be worth checking.