My 1983 O’Day 28 is equipped with a 5 gallon hot water tank. After 5 minutes of engine running, sea water still was not discharging by the transom exhaust. My understanding is that sea water circulate through the engine cooling and run afterward in the hot water heater coils. How long does it normally takes to see the water discharging? To avoid overheating the engine, I had a valve installed on the HWT intake. Thanks
Hot water heater
- Thread starter Mojo4166
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Pump problem
Not sure about your system but usually the raw water & engine coolant are 2 different systems the raw water is circulated through the heat exchanger and then exausted with the air from your engine.You should see this water within a minute after starting the engine. The engine coolant is circulated through the hot water tank & then the heat exchanger where it is cooled by the raw water system and then back in the engine. The engine coolant should be a mixture of antifreeze and freshwater. Hope this info will help you with the problem. Things to check. Sea cock is turned on. Water pump is working Ok, check the rubber empellor. ( This is oftem the problem) Check the heat exchanger for any obstruction. check all hose etc etc. Good luck.
Not sure about your system but usually the raw water & engine coolant are 2 different systems the raw water is circulated through the heat exchanger and then exausted with the air from your engine.You should see this water within a minute after starting the engine. The engine coolant is circulated through the hot water tank & then the heat exchanger where it is cooled by the raw water system and then back in the engine. The engine coolant should be a mixture of antifreeze and freshwater. Hope this info will help you with the problem. Things to check. Sea cock is turned on. Water pump is working Ok, check the rubber empellor. ( This is oftem the problem) Check the heat exchanger for any obstruction. check all hose etc etc. Good luck.
Water heater
The layout of the cooling system is dependant on what engine you have & not necessarily related to a particular boat model. Normally, the raw water system would be inlet sea-cock -> strainer(optional) ->raw water pump->heat exchanger->exhaust->overboard The engine coolant (a closed loop) would usually run thru the water heater and the heater would actually improve engine cooling by drawing off some of the heat from the anti-freeze mix in the engine loop. As noted in the previous posts, you should see raw water from the exhaust in a fairly short time. Make sure your inlet isn't blocked, the pump impeller is OK and the heat exchanger is clear. Also,verify that the exhaust riser ( the point where the raw water is fed into the exhaust) is not blocked by scale & corrosion.
The layout of the cooling system is dependant on what engine you have & not necessarily related to a particular boat model. Normally, the raw water system would be inlet sea-cock -> strainer(optional) ->raw water pump->heat exchanger->exhaust->overboard The engine coolant (a closed loop) would usually run thru the water heater and the heater would actually improve engine cooling by drawing off some of the heat from the anti-freeze mix in the engine loop. As noted in the previous posts, you should see raw water from the exhaust in a fairly short time. Make sure your inlet isn't blocked, the pump impeller is OK and the heat exchanger is clear. Also,verify that the exhaust riser ( the point where the raw water is fed into the exhaust) is not blocked by scale & corrosion.
Not Related
Mojo, This response is based on my O'28 with a Universal fresh water cooled 10 HP. Yes, the water heater works off the heat generated by the engine, but there is no physical connection of the raw engine cooling water. You have a problem with the primary cooling system for your engine. Check the path as listed by Nova Scotia and somewhere in that path will be the problem. My O'28 starts overboard discharge almost immediatly upon starting. Possibly whoever installed the shut-off valve did not get things back in the right place. The water heater has no effect what so ever in the overheating of your engine. If you installed the valve because of overR566heating, you probably have a raw water impeller that is about to die or already has. The only way that the water heater could effect your engine is if the heat exchanger has a problem and the two different fluids are mixing. Even then someting should be coming out the back within seconds of starting. PM
Mojo, This response is based on my O'28 with a Universal fresh water cooled 10 HP. Yes, the water heater works off the heat generated by the engine, but there is no physical connection of the raw engine cooling water. You have a problem with the primary cooling system for your engine. Check the path as listed by Nova Scotia and somewhere in that path will be the problem. My O'28 starts overboard discharge almost immediatly upon starting. Possibly whoever installed the shut-off valve did not get things back in the right place. The water heater has no effect what so ever in the overheating of your engine. If you installed the valve because of overR566heating, you probably have a raw water impeller that is about to die or already has. The only way that the water heater could effect your engine is if the heat exchanger has a problem and the two different fluids are mixing. Even then someting should be coming out the back within seconds of starting. PM
Cold running engine
From what I have experienced with my 1983 O'Day 28 with Universal 11 hp engine, water does not come out the exhaust until the themostat opens and the engine begins to warm up. Sometimes this is 5 minutes or perhaps more. There might be a few drops prior to that time. The engine runs at about 140 degrees. Once it is warm and the flow from the exhaust begins, it is more or less steady, but frequently in spurts. I have had this boat for 7 years and each time I start it, I end up wondering if the impeller has failed since the last sail.
From what I have experienced with my 1983 O'Day 28 with Universal 11 hp engine, water does not come out the exhaust until the themostat opens and the engine begins to warm up. Sometimes this is 5 minutes or perhaps more. There might be a few drops prior to that time. The engine runs at about 140 degrees. Once it is warm and the flow from the exhaust begins, it is more or less steady, but frequently in spurts. I have had this boat for 7 years and each time I start it, I end up wondering if the impeller has failed since the last sail.
No bypass??
Wayne - Isn't there supposed to be a bypass to allow some flow of raw water thru the exhaust before the thermostat opens ?? My engine is raw water cooled ( Yanmar YSB-8 in an O'Day 27) and my exhaust system is made up of rubber hose, a plastic Vetus Waterlock & a plastic Vetus gooseneck. I'd be kinda worried abt the life span of the exhaust hose & plastic bits if there wasn't any water flow at all for 5 mins± on every cold start. True, there's some residual water in the waterlock, but the exhaust gas is hot as soon as combustion ocurs.
Wayne - Isn't there supposed to be a bypass to allow some flow of raw water thru the exhaust before the thermostat opens ?? My engine is raw water cooled ( Yanmar YSB-8 in an O'Day 27) and my exhaust system is made up of rubber hose, a plastic Vetus Waterlock & a plastic Vetus gooseneck. I'd be kinda worried abt the life span of the exhaust hose & plastic bits if there wasn't any water flow at all for 5 mins± on every cold start. True, there's some residual water in the waterlock, but the exhaust gas is hot as soon as combustion ocurs.
Hot water issue
Thanks everyone for your comments & tips. I guess I’ll have to wait until the boat is back to its slip to investigate furthermore. I know the water pump works perfectly. Seconds after the engine is started, raw water rushes out of the exhaust. As soon as I open the valve installed on the water heater line, raw water only drips. I’ll will disconnect the lines one by one and see where the dam water go. Thanks again.
Thanks everyone for your comments & tips. I guess I’ll have to wait until the boat is back to its slip to investigate furthermore. I know the water pump works perfectly. Seconds after the engine is started, raw water rushes out of the exhaust. As soon as I open the valve installed on the water heater line, raw water only drips. I’ll will disconnect the lines one by one and see where the dam water go. Thanks again.
Missing Bypass?
TT: I don't know if there is supposed to be a bypass or not. I have checked the cooling diagram in the manual and the engine seems to match it. Exhaust gas, of course, exits as soon as the engine starts. None of the hoses seem to be particularly hot when the water does start to be exhausted. Wayne
TT: I don't know if there is supposed to be a bypass or not. I have checked the cooling diagram in the manual and the engine seems to match it. Exhaust gas, of course, exits as soon as the engine starts. None of the hoses seem to be particularly hot when the water does start to be exhausted. Wayne
Cooling systems & water heaters
Mojo - I'd check with whoever sells/services your engine: you didn't specify what make it is in your post. The symptoms you described sound rather strange, almost as if the water heater is getting heat off the raw water side of the cooling system. This strikes me as odd, simply because the raw water flow would normally not be nearly as hot as the coolant circulating thru the engine and therefore your water heater wouldn't be as effective. In raw water cooled engines like mine the thermostat opens @ 130°F± and the engine shouldn't run much warmer than that, to prevent salt in the raw water from crystalizing & forming deposits in the cooling passages of the engine. In a "fresh water" cooled engine, the engine can run hotter as the coolant, an anti-freeze solution, contains corrosion inhibitors and no salt or minerals so salt crystalization isn't an issue. Diesels run better when they're hotter and a FWC engine can have an operating temp. in the 180-200°F range, while the raw water stays at a relatively cool temp. Your water heater is just another heat exchanger: the hot engine coolant is piped thru it and gives off heat to the domestic water in the heater tank. There should be no mixing of the two fluids. What I described is the most common set-up, but there may be other configurations that I'm not familiar with. By the way, make sure there's no air trapped in the engine coolant loop: this can cause engine overheating as the coolant can't circulate properly. Just like a car heater: you have to bleed the air out of the system for it to work.
Mojo - I'd check with whoever sells/services your engine: you didn't specify what make it is in your post. The symptoms you described sound rather strange, almost as if the water heater is getting heat off the raw water side of the cooling system. This strikes me as odd, simply because the raw water flow would normally not be nearly as hot as the coolant circulating thru the engine and therefore your water heater wouldn't be as effective. In raw water cooled engines like mine the thermostat opens @ 130°F± and the engine shouldn't run much warmer than that, to prevent salt in the raw water from crystalizing & forming deposits in the cooling passages of the engine. In a "fresh water" cooled engine, the engine can run hotter as the coolant, an anti-freeze solution, contains corrosion inhibitors and no salt or minerals so salt crystalization isn't an issue. Diesels run better when they're hotter and a FWC engine can have an operating temp. in the 180-200°F range, while the raw water stays at a relatively cool temp. Your water heater is just another heat exchanger: the hot engine coolant is piped thru it and gives off heat to the domestic water in the heater tank. There should be no mixing of the two fluids. What I described is the most common set-up, but there may be other configurations that I'm not familiar with. By the way, make sure there's no air trapped in the engine coolant loop: this can cause engine overheating as the coolant can't circulate properly. Just like a car heater: you have to bleed the air out of the system for it to work.
Wayne
Don't know what to tell you: you say it checks out with the engine manual & it's been working OK for the 7 yrs you've owned the boat, so it must be OK. The 140°F operating temp you mentioned seems kinda cool for a FWC engine, but if the manual calls for a 140° t'stat then that's the temp the designers wanted the thing to run at. I've always believed that a marine diesel runs better & more efficiently at a higher temp, as is the case for diesels & gas engines in automotive use. Can't understand why you don't see raw water out of the exhaust untill the engine warms up though: the raw water flow should be independant of the engine t'stat in a FWC system. My old Yanmar is raw-water cooled & before the t'stat opens a postion of the raw water is sent directly into the exhaust, to prevent cooking the exhaust hoses. As the engine warms up, the t'stat opens and more of the coolant flow passes thru the engine before entering the exhaust, but there's always some water directed into the exhaust at all times. It comes out the exhaust pipe in burps & farts as the exhaust gas has to develop enough pressure to overcome the static head of water in the waterlock, so the stream isn't a steady flow as from a tap, but it's always there as soon as the engine lights up.
Don't know what to tell you: you say it checks out with the engine manual & it's been working OK for the 7 yrs you've owned the boat, so it must be OK. The 140°F operating temp you mentioned seems kinda cool for a FWC engine, but if the manual calls for a 140° t'stat then that's the temp the designers wanted the thing to run at. I've always believed that a marine diesel runs better & more efficiently at a higher temp, as is the case for diesels & gas engines in automotive use. Can't understand why you don't see raw water out of the exhaust untill the engine warms up though: the raw water flow should be independant of the engine t'stat in a FWC system. My old Yanmar is raw-water cooled & before the t'stat opens a postion of the raw water is sent directly into the exhaust, to prevent cooking the exhaust hoses. As the engine warms up, the t'stat opens and more of the coolant flow passes thru the engine before entering the exhaust, but there's always some water directed into the exhaust at all times. It comes out the exhaust pipe in burps & farts as the exhaust gas has to develop enough pressure to overcome the static head of water in the waterlock, so the stream isn't a steady flow as from a tap, but it's always there as soon as the engine lights up.
My engine is a 1982 Universal Atomic 4 diesel and is raw water cooled. As TT stated the hot water tank must be regarded as an additional heat exchanger. Eventually raw water should find its way toward the exhaust system. I had my engine running for more than 5 minutes to see just little water coming out of the stern. This is why a valve was installed to direct the cooling water to the exhaust pipe. When I both this used ODay 2 year ago, it had been sitting on a cradle for at least 2 years. I am no mechanic but is it possible that an internal moving part is rusted or obstructed? Yvon (Mojo)
Sorry Mojo
I made the mistake of assuming that you guys with the "big" 28's all had FWC engines, while the older 27's like mine came with the earlier, raw water cooled engines. Wayne's posts suggest that he's running into the same delay in seeing water from the exhaust as you are, and that it's because the thermostat isn't opening untill the engine's warmed up. I'm surprised that there isn't some bypass that allows raw water into the exhaust ASAP, as is the case with my Yanmar, but Wayne's set-up has apparently been working for some time, so who's to argue with success? Tony
I made the mistake of assuming that you guys with the "big" 28's all had FWC engines, while the older 27's like mine came with the earlier, raw water cooled engines. Wayne's posts suggest that he's running into the same delay in seeing water from the exhaust as you are, and that it's because the thermostat isn't opening untill the engine's warmed up. I'm surprised that there isn't some bypass that allows raw water into the exhaust ASAP, as is the case with my Yanmar, but Wayne's set-up has apparently been working for some time, so who's to argue with success? Tony
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