| Marine exhausts systems are an important and | | | | ensured it works. To remove water from inside |
| often overlooked part of a marine engine. Most | | | | the combustion chambers, first remove all |
| vessels have a 'wet' exhaust system. Salt water | | | | injectors, crank engine over to blow water out, |
| is injected at the riser - the outlet for exhaust | | | | refit injectors, bleed injector lines, and start. Then |
| from the exhaust manifold. This mixture of | | | | leave motor running until exhaust sorted out. |
| exhaust gas and water is then passed through a | | | | Check to see that the riser is not coked up or |
| series of bends until it exits the boat, preferably | | | | corroded - a common problem. To check the |
| at the stern. | | | | exhaust riser remove the exhaust hose from the |
| Exhaust gases mixed with salt water create a | | | | riser (often a difficult procedure) and look up the |
| highly corrosive compound. This is why exhaust | | | | pipe to see if it is restricted by exhaust/salt build |
| systems are commonly made using non-corrosive | | | | up. If build up is excessive the riser will have to be |
| components such as nitrile rubber reinforced hose | | | | removed to check the engine end of the pipe. |
| (brown - not green - stripe), galvanized steel, | | | | Coke can be scraped out to provide a short term |
| fiberglass or plastic. The purpose of these | | | | fix although often the riser will have to be |
| components, which vary in size and shape | | | | replaced. There are aftermarket systems which |
| depending on the engine size and layout of the | | | | vary in quality. Make sure you fit the right design |
| engine room, is to prevent hydraulicing of the | | | | for the application. |
| engine. This is caused when an engine has filled | | | | Ensure your water-lock is low enough and big |
| with salt water which has entered via the exhaust | | | | enough to hold all the water in exhaust system. Is |
| and can cause extensive damage if left for more | | | | there a gooseneck or central vertical loop in the |
| than two hours. Water enters the exhaust from | | | | exhaust hose at the transom exit? Is there a |
| wave action at stern and poor exhaust design. In | | | | siphon break and is it functioning properly - no |
| some ocean conditions, such as a following sea, | | | | leaking valves? |
| water can be forced back up the exhaust when | | | | Exhaust gas is poisonous and can cause sea |
| the engine is not running. Poorly designed exhausts | | | | sickness and headaches. Replace any faulty parts |
| allow water to flow back and fill the waterlock | | | | immediately. Use double hose clamps on each joint |
| muffler box then up the hose into the exhaust | | | | or, preferably, super clamps, bolt style, and |
| manifold, through the exhaust valves and into the | | | | exhaust cement if need be. Hot sections should |
| combustion chamber. With the engine full of water | | | | be lagged with fiberglass tape to prevent burns. |
| the engine cannot crank over as it is cannot | | | | Beware of asbestos lagging. Many older vessels |
| compress water. | | | | and marine engine installations had exhaust |
| You will know your engine is hydrauliced if it will | | | | systems that were lagged with asbestos tape |
| not turn over - generally after a long sailing period | | | | and rope. Asbestos sound-proofing was also |
| - and you have removed the starter motor and | | | | common in older boats. |