While winterizing my Yanmar 18 today on H320, the raw water intake wasn't taking while in idle. The water just sat there, yet it was coming out the stern. After five minutes I revved up the engine and the suction/intake proceeded as normal. What gives? Thanks.
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Could be the pump
Bill - I had a similar problem on my YSM12 Yanmar. The pump kept losing its prime and would not pull water thru unless I bled the system. Turned out the face plate on the impeller cover was worn down causing the pump to lose its prime occassionaly. You could either replace the cover or better yet - just the whole pump.
Bill - I had a similar problem on my YSM12 Yanmar. The pump kept losing its prime and would not pull water thru unless I bled the system. Turned out the face plate on the impeller cover was worn down causing the pump to lose its prime occassionaly. You could either replace the cover or better yet - just the whole pump.
Could be a partial clog...
...at the raw water intake. If the boat has been setting in the water, some growth could be fouling the intake. As the engine gets revved, it may be sucking what it needs and draws the water. Are you in salt water?
...at the raw water intake. If the boat has been setting in the water, some growth could be fouling the intake. As the engine gets revved, it may be sucking what it needs and draws the water. Are you in salt water?
I'm in brackish water...
... Sara Creek off the York River of the Chesapeake Bay. I hadn't considered the priming concept, since I thought these were self-priming. In any case, I know the water pump is okay because I just replaced the impeller and resealed the gasket tightly. Could it be a gravity fluke, since I had the tall funnel high up to about the level of the airhorn? Again, the issue is water not pumping through at idle.
... Sara Creek off the York River of the Chesapeake Bay. I hadn't considered the priming concept, since I thought these were self-priming. In any case, I know the water pump is okay because I just replaced the impeller and resealed the gasket tightly. Could it be a gravity fluke, since I had the tall funnel high up to about the level of the airhorn? Again, the issue is water not pumping through at idle.
Bill , the impeller pump is positive displacement.
If it is turning it must be sucking either air or water or be blocked. Since you were supplying it with a positive head and had water coming from the exhaust and it started taking from the supply above an idle I think that you have a gremlin and need to call in a Witch Doctor. I can't think of a logical explaination.
If it is turning it must be sucking either air or water or be blocked. Since you were supplying it with a positive head and had water coming from the exhaust and it started taking from the supply above an idle I think that you have a gremlin and need to call in a Witch Doctor. I can't think of a logical explaination.
Air
doesen't matter if you replaced the impeller....the plate cover can be worn and it will still suck air. I had the same problem.
doesen't matter if you replaced the impeller....the plate cover can be worn and it will still suck air. I had the same problem.
Water in the muffler
Air leak in the impeller that was overcome by revving the engine. The water coming out the exhaust port was "old" water stored in the muffler. When you reved up the engine the air leak could not provide all the volume so the "new" water made up the difference.
Air leak in the impeller that was overcome by revving the engine. The water coming out the exhaust port was "old" water stored in the muffler. When you reved up the engine the air leak could not provide all the volume so the "new" water made up the difference.
Sucking water
I have an Atomic 4 and do some of the same cooling system winterization processes that you do on a diesel as well (running fresh water through raw water cooling system). I have never experienced your situation as I try not to engage our prop when on the hard (fear of dreaded cutlass bearing replacment job) during winterization and our water pump always sucked instead of blowed. I replaced this water pump 3 years ago, under duress as we had an overheating condition. The rubber impeller spins around in the pump body and both the rubber and metal wear down (especially in silty, gritty water - read abrasives). I am not trying to tax your checking account but I agree with Rob from Mattituck and only partially with Ross that due to the unit wearing down your pump is only sucking air at idle speed. There will be a good amound of water in the engine and exhaust systems that the air can blow out for some time. If I am not mistaken the process of burning gasonline will produce some water (and if not water) vapor that will condense into a liquid - you would still hear and see some moisture dripping out(Ross, please follow up on this, you know you love to correct all the Dr. Science loose ends on these discussions). All I am saying is that the replacement water pump will set you back several hundred and you will get to curse a lot like I did while replacing mine, and you will know a lot more about this important part of your engine. My water pump has a grease valve that needs to be refilled every season and turned a half a screw before each use or every 5 hours (like I do it, but at least I know it is there). You keep your old water pump as a backup and see if you can figure out why it is not working at idle speed only. I would not like to discover that a few grains of sand did in my cooling system when I needed it most. That my 2 cents. CalebD Link below is for the replacement water pump for MY A4 engine.
I have an Atomic 4 and do some of the same cooling system winterization processes that you do on a diesel as well (running fresh water through raw water cooling system). I have never experienced your situation as I try not to engage our prop when on the hard (fear of dreaded cutlass bearing replacment job) during winterization and our water pump always sucked instead of blowed. I replaced this water pump 3 years ago, under duress as we had an overheating condition. The rubber impeller spins around in the pump body and both the rubber and metal wear down (especially in silty, gritty water - read abrasives). I am not trying to tax your checking account but I agree with Rob from Mattituck and only partially with Ross that due to the unit wearing down your pump is only sucking air at idle speed. There will be a good amound of water in the engine and exhaust systems that the air can blow out for some time. If I am not mistaken the process of burning gasonline will produce some water (and if not water) vapor that will condense into a liquid - you would still hear and see some moisture dripping out(Ross, please follow up on this, you know you love to correct all the Dr. Science loose ends on these discussions). All I am saying is that the replacement water pump will set you back several hundred and you will get to curse a lot like I did while replacing mine, and you will know a lot more about this important part of your engine. My water pump has a grease valve that needs to be refilled every season and turned a half a screw before each use or every 5 hours (like I do it, but at least I know it is there). You keep your old water pump as a backup and see if you can figure out why it is not working at idle speed only. I would not like to discover that a few grains of sand did in my cooling system when I needed it most. That my 2 cents. CalebD Link below is for the replacement water pump for MY A4 engine.
Maby its not the pump at all, but something else?
What about the thermostat? If the engine is till cold, water will be kept from going into the engine untill it warms up, once the water inside the engine warms up, the thermostat will open, allowing the water to be sucked up into it, and the heated water to be expelled.
What about the thermostat? If the engine is till cold, water will be kept from going into the engine untill it warms up, once the water inside the engine warms up, the thermostat will open, allowing the water to be sucked up into it, and the heated water to be expelled.
Thermostat and gravity feed
Mike makes a good point here. Did the pump work once the engine was warm, and you idled back down? I have a connection spliced in the line for winterizing for my Yanmar 2qm15(?) The only way I can get the engine to take antifreeze is to close the raw water intake, and gravity feed the antifreeze through a funnel. I have to lift the funnel just about 5 feet above the level of the intake. I've never tried warming up the engine first though. Never even thought about the need.
Mike makes a good point here. Did the pump work once the engine was warm, and you idled back down? I have a connection spliced in the line for winterizing for my Yanmar 2qm15(?) The only way I can get the engine to take antifreeze is to close the raw water intake, and gravity feed the antifreeze through a funnel. I have to lift the funnel just about 5 feet above the level of the intake. I've never tried warming up the engine first though. Never even thought about the need.
Bill, sounds like the blades to the impeller,
have parted ways. An impeller with no blades will not pump. If you have replaced the impeller, if it had no blades.... where are they. You may have to back flush to expell the parted blades that have lodged in the motor. Note that Ross is the correct answer. If that is not true, se the above. r.w.landau
have parted ways. An impeller with no blades will not pump. If you have replaced the impeller, if it had no blades.... where are they. You may have to back flush to expell the parted blades that have lodged in the motor. Note that Ross is the correct answer. If that is not true, se the above. r.w.landau
Check R.W. Landau's post, below
Some impellers have "slipped" in the past. That is, the hub loosens at the shaft and "free wheels" without turning the impeller and the blades that bring in the raw water. That may be another source of the problem.
Some impellers have "slipped" in the past. That is, the hub loosens at the shaft and "free wheels" without turning the impeller and the blades that bring in the raw water. That may be another source of the problem.
I replace my themostat every 2 years
and this year we extracted the thermostat before pumping fresh water and antifreeze through the system. Ross is again correct, that the thermostat does need to be bypassed during overhaul (see what I am saying about Ross knowing all the technical this's and that's about everything; we must all be in contact with God or Bietzpadlin or something through the web). What I really wanted Ross to correct me on was the gasses produced by combustion of gasoline (and oil). I have driven behind enough cars to know that they occasionally drip water out of their exhaust tail pipes. This would be water vapor entering the exhaust system from the engine, not from the cooling system, and could supply a continuall drip to your manifold and water lift muffler. Anyway, Ross is right. Caleb
and this year we extracted the thermostat before pumping fresh water and antifreeze through the system. Ross is again correct, that the thermostat does need to be bypassed during overhaul (see what I am saying about Ross knowing all the technical this's and that's about everything; we must all be in contact with God or Bietzpadlin or something through the web). What I really wanted Ross to correct me on was the gasses produced by combustion of gasoline (and oil). I have driven behind enough cars to know that they occasionally drip water out of their exhaust tail pipes. This would be water vapor entering the exhaust system from the engine, not from the cooling system, and could supply a continuall drip to your manifold and water lift muffler. Anyway, Ross is right. Caleb
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