My boat has had intermittent issues with water cooling
since I bought it a couple of years ago.
is a Volvo
MD7A 13hp engine
with sea water cooling
. The water comes in from the saildrive
leg, up to the water pump, then round a siphon loop before going into the engine. The water pump sits about 6 inches above the effective water level in the inlet hose. Once the pump is primed the water flow if fine - occasionally it will prime by giving the engine a rev, but more usually I need to fill the inlet hose then re-attach to the pump.
I have replaced the inlet hose, the short copper pipe that push fits into the pump, and the o-ring, and experimented with sealant
and putty around these joins with little effect.
I have also checked the impeller which is intact, turns with the engine and does not seem to turn independently of the shaft (have heard the inner barrel of the impeller can sometimes detach from the rest). I have removed the outlet hose from the siphon loop and taken the inlet hose off the saildrive
leg and into a bucket of water so both hoses are loose, but still no water through.
Next I am going to try sanding
the face of the pump housing and the pump cover, then putting in a new impeller and gasket
Should I be trying anything else? And if all else fails is there a practical way to manually prime the line? Was wondering if an inline pump like the fuel
primer bulbs would be worth trying?