Yanmar 2QM15 raw water pump problem
Hi, I am new member and I have learned something good from SailNet member: put the starting key into the raw water intake valve.... yes if I can remember to put it there.
My boat is 1980 Spencer 34 Sloop, flat bottom U shape hull and the engine is forward under the V berth,because of this the raw water intake was only about 16 inch below water line. The Yanmar 2QM15 (raw water cool ) has about 2300 hours since new. She sailed beautiful and the engine run faultlessly in any sea conditions for over 27 years until this summer. In the pass few years the raw water pump has been dripping water from the pump shaft seal, so last winter I replaced the seal and put in new impeller put in good grease to lubricate but notice the housing wall and the cover plate were worn. This spring I took her out sailing in Gulf Island for about a week, had a good sailing in strong breeze and the sea was choppy but not really disturbed and the engine run smooth no problem. Under the engine was dry no more water dripping. This Summer I sailed up to Desolation Sound for about 4 weeks, used the engine often when calm no problem. On the way back, very strong Northwest wind was blowing 26 kt behind me running with jib only (engine not run) doing well over 6 knot, 3 foot sea from behind white caps all over the boat get toasted around. When arrived at the entrance of Pender Harbor, drop sail start the engine and within minutes the temperature alarm went off. Shut the engine off, rehoist the jib and sailed into the Harbor good thing the wind blow right into the harbor. After drop anchor, inspect the intake water filter no water in it, released the top screw air came out, water came in to the filter disconnect the hose to the water pump, water came out of the hose, water dripping out from the pump (from the engine). inspect the impeller looks OK Put the system back in, did few minutes of hand cranked (decompress the engine) to make sure the water pumped into the engine and start the engine runs OK water came out of the exhaust. Next day flat calm motor all the way to Gulf Island all day no problem. Sailing and motoring for several days in Gulf Island no problem. On the way back to home port (up in Fraser river in Landner BC) motor to Pollier Pass ( inside was flat calm, 16 kt NW wind out side in Georgia strait) 70 minute after slack water, flood water was about 4knot. The tide rip out side was big 3 foot waves white caps all over had the mainsail up. As soon the boat bouncing up and down the water temperature alarm went off . Shut the engine off and sail with main only, tried to hoist the genoa but the halyard got wrapped in to the top spreader took a while to get it off and hoist the gene and sail on up to the middle of the strait before the wind died. The sea still had the NW swell and boat was still bouncing some what but no more white caps.Went down to the engine room and bleed the water intake system (I became expert by then) started the engine everything was OK motor to Sand Head and all the way to Captainís Cove Marine in Ladner no Problem. I took out all the intake hoses and inspect, found no damage no soft spot no kink all the clamps are OK.
What I think was these:
The water pump was no longer self priming (the ability to create limited vacuum in the hose of about 4-5 ft length to pump the air out so water could get in) because of worn housing and cover plate, but as long as water in the intake hose and no air in it, it will pump the water.
With only about 16 inches deep from the sea surface, the water in that layer of sea was very well air rated especially in choppy confused sea. That is how the air got in even the water intake was not exposed above the water line (as all builder claim).
Yanmar does not sell the pump housing only the complete pump for $800 CAD. and have to order form Chicago.
I intend to replace with other make pump of similar size or even electric pump.
Before replaced the bad shaft seal and the water was dripping, probably it act as air bleeder, that was why I had no air lock problem before. So I intend to build air breathing system with a little tank for experiment until I found water pump replacement (not the :confused:$800 one).
Any comments and suggestions and advice from all member are welcome and appreciate.
What about re-locating the intake thru-hull to a spot on your bottom that will always be under water? It would mean a longer hose run, but so what?
I find it really hard to believe your engine is located in your forepeak! Really? Where is your propeller? How does the shaft run through your boat? Would love to see pictures!
I have the same engine in my '78 C&C. This spring I had to rebuild my waterpump because a replacement was too expensive. Yanmar wanted about $600 to replace it. But I bought replacement parts for about $80 and totally rebuilt the pump. As long as the housing itself is good it is a pretty simple job. You can get an exploded view of the engine here: literature (thanks to NOLASAILING)
In spite of the rebuild though I have had similar problems with air getting into the water intake pipe and breaking the suction after or while I was being bounced around by the waves. I don't think it is because the water intake was too close to the surface, but I don't know definitively what caused the problem.
You said the Housing and cover plate were worn. Try a new cover plate and a new gasket. Or if the outside of the cover is clean and flat, turn it inside out. You may be loosing suction here especially since you said you have a leak.
Thanks for the info and advice folks. To relocate the intake I have to take the boat out and maybe gain extra 3 to 4 inches by the keel, but it work fine for 27 years. Yes the engine is in the forepeak and has a long shaft run under the mast step (a box) then to U joint and a short shaft to the propeller (b etween the fin keel and the rudder) same as 1980 Yamaha 30 and 33 sail boat (popular concept in 1980 by IOR). I will send a picture if I can find how to do it. I will flip over the cover plate and re route the hoses for shorter run and install a breathe tube or tank.
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