Hi guys boat runs great 5years and then did a little work , new water pump, thermostat , gas and water seperator, raw water intake strainer all brand new. I could run it 7 or 12 hrs , doesnt matter, but all of a sudden it starts up and no water pumping out , blocked somewhere. It happenned 5 times yhis year , never in the last 5 years but this year , boom never on the run only at a intial start.I went all over the vinyard ran great one day then boom it takes abour five hrs, then it starts up. Runs great then i shot it off to sail the at any given time , no water . The mechanic told me old engine and sediment builds up and blocks it , he sent me a new 90 degree elbow at thye the thermostat but still at any given time it doesnt pump yet i will run 7 or 10 hrs at a time , what gives ?? HAS any one have this similar problem ?
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The way that thermostat works is when the engine is cool, it channels all the water from the water pump in to the exhaust beyond the riser. When the engine gets hot, the thermostat allows engine water to flow with mixes with the water to the exhaust and cools the exiting gases. Since the pump is new, I would check to see that you haven't built up too much water intake resistance with the water separator and strainer...You can do that by opening up the waterpump output hose and crank the engine without starting it. You should have good out output flow while cranking....you can take out the plugs to reduce the load on your starte and don't crank longer than 20 seconds at a time.
Possible exhaust manifold problem .....
My bet is a plugged exhaust manifold. The water jacketed exhaust manifold is prone to giving off huge platelettes of rust that can break loose internally and totally block the entire raw water cooling circuit. When the engine is running the attempted flow will hold the huge plateletts across the flow path and no water comes out the exhaust outlet; Shut the engine down and eventually the slab drops back down and the water can flow again, etc. This is very common to atomic-4s that are winter stored with all of the cooling water drained. Old engines should NOT be 'dried out'. Simple test: when there is no water flow, carefully remove the rubber hose at the aft end of manifold and see if water is flowing at about 3 gallons per minute at 2000 rpm. If not, remove the hose at the front end of the exhaust manifold and check the flow. If there is flow into the manifold but not out ...... take a long stiff wire and shove it inside the water jacket side of the manifold to break up the rust slabs. Better to remove the manifold, break up the rust slabs then invert the manifold and shake out all the broken rust slabs. Once you get all the rust out, consider to 'pickle' the manifold (and engine) with a non acid boiler descaler such as Marsolve, etc. Then do a pressure check on the 'water-side' of the manifold to ensure that you havent developed any pin hole leaks that will allow water be sucked back into the engine when the engine shuts down --- very bad. Such rust slabs form when the engine is stored with the water drained from the cooling system. Cast iron castings are like an 'onion' and if ferric (bad) rust begins to form it will begin to loosen one layer of the onion at a time. If storing the engine for long periods its better to fill the system with antifreeze with rust inhibiters added. Hope this helps.
My bet is a plugged exhaust manifold. The water jacketed exhaust manifold is prone to giving off huge platelettes of rust that can break loose internally and totally block the entire raw water cooling circuit. When the engine is running the attempted flow will hold the huge plateletts across the flow path and no water comes out the exhaust outlet; Shut the engine down and eventually the slab drops back down and the water can flow again, etc. This is very common to atomic-4s that are winter stored with all of the cooling water drained. Old engines should NOT be 'dried out'. Simple test: when there is no water flow, carefully remove the rubber hose at the aft end of manifold and see if water is flowing at about 3 gallons per minute at 2000 rpm. If not, remove the hose at the front end of the exhaust manifold and check the flow. If there is flow into the manifold but not out ...... take a long stiff wire and shove it inside the water jacket side of the manifold to break up the rust slabs. Better to remove the manifold, break up the rust slabs then invert the manifold and shake out all the broken rust slabs. Once you get all the rust out, consider to 'pickle' the manifold (and engine) with a non acid boiler descaler such as Marsolve, etc. Then do a pressure check on the 'water-side' of the manifold to ensure that you havent developed any pin hole leaks that will allow water be sucked back into the engine when the engine shuts down --- very bad. Such rust slabs form when the engine is stored with the water drained from the cooling system. Cast iron castings are like an 'onion' and if ferric (bad) rust begins to form it will begin to loosen one layer of the onion at a time. If storing the engine for long periods its better to fill the system with antifreeze with rust inhibiters added. Hope this helps.
Manifold flakes
Have the same problem occasionally. If you are at the dock, pull the hose off of the rear of the manifold, attach the a dock hose to the rear of the manifold, then run a piece of hose from the front of the manifold into a bucket and back-flush it. It will loosen the scale and get you going. Of course, the proper way is to remove the manifold and take it to a machine shop and have it hot-tanked, but you may break off the manifold studs and then you have compounded your problems. It's best to save that until you have to do more extensive repairs. PS If you are underway and have the problem, have a piece of hose long enough to reach from the output side of the water pump to the manifold, hook it up and do a partial backflush that way. You just have to run it for a few seconds like that, not long enough to overheat the engine.
Have the same problem occasionally. If you are at the dock, pull the hose off of the rear of the manifold, attach the a dock hose to the rear of the manifold, then run a piece of hose from the front of the manifold into a bucket and back-flush it. It will loosen the scale and get you going. Of course, the proper way is to remove the manifold and take it to a machine shop and have it hot-tanked, but you may break off the manifold studs and then you have compounded your problems. It's best to save that until you have to do more extensive repairs. PS If you are underway and have the problem, have a piece of hose long enough to reach from the output side of the water pump to the manifold, hook it up and do a partial backflush that way. You just have to run it for a few seconds like that, not long enough to overheat the engine.
WATER FLOW
I concur with what the other guys said. To take it one step further. I pulled the head on My engine a couple of years ago because of stuck valves. Really not that difficult. While I had the head off I used a drill bit slightly ssmaller than the journals in the head and block and twisted the bit back and forth with my fingers to open up all the blocked journals in the head and block. Worked like a charm, opened everything up so that the water could flow everywhere. Use a portable vacuum to suck out all the loose scale and change your oil. Good Luck
I concur with what the other guys said. To take it one step further. I pulled the head on My engine a couple of years ago because of stuck valves. Really not that difficult. While I had the head off I used a drill bit slightly ssmaller than the journals in the head and block and twisted the bit back and forth with my fingers to open up all the blocked journals in the head and block. Worked like a charm, opened everything up so that the water could flow everywhere. Use a portable vacuum to suck out all the loose scale and change your oil. Good Luck
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