3827299 Volvo.Penta Manometer

Where possible mount the strainer so that the top is just above the waterline to facilitate cleaning.Keel Cooling or Skin Cooling
Keel cooling or skin cooling is a closed circuit method of cooling that uses only coolant with 50/50 antifreeze mix.A properly designed and installed cooling system is essential for satisfactory engine life and performance.Keel cooling is a cooling system that uses a group of tubes, pipes or channels attached to the outside of the hull below the waterline as a heat exchanger. Keel coolers are used in preference to the standard raw water cooled engine mounted heat exchanger when operating in areas that have heavy silt and debris in the water that would erode the heat exchanger tubes or block them.Keel cooling is used in Arctic conditions to avoid the problems of freezing that is experienced with the raw water circuit on the heat exchanger cooling system.Keel coolers are available in standard designs from several manufacturers. These units are simple to install and are sized by the manufacturer for the engine model and boat application. Commercial coolers are made of erosion resistant materials and have a relatively high heat transfer efficiency.The disadvantage of external keel coolers is that they are vulnerable to damage and therefor must be guarded. An alternative to the commercially available coolers are fabricated keel coolers manufactured by the boat builder as part of the hull construction. These coolers are not as efficient and must be designed oversize to allow for a decrease in performance that follows the formation of rust, scale and marine growth on the keel cooler.
If the genset is a replacement package and the original cooling system, keel cooler and expansion tank, is to be reused, then it is essential that the system thoroughly flushed to remove sludge that may be in the system. Failure to remove sludge could block air bleeds leading to the engine overheating.
Sizing the CoolersCommercial keel coolers are manufactured in a variety of sizes and shapes. The keel cooler manufacturer will recommend a keel cooler when provided with the following data:-* Engine model and rating* Engine data sheet* Heat Rejection (see table below)* Engine Coolant Flow* Max. coolant temperatures from grid cooler* Maximum raw water temperature* Pipe connections - Min. 44mm (1.75") o.d; Min. 38mm (1.5") bore* Coolant - 50/50 antifreeze mix Figure (A) shows the connections (A1) and flow (A2) for the 4 cylinder engines to the keel cooler (A3). The size of the connections (A1) are both 38mm (1 1/2" inches). Figure (B) shows the connections (B1) and flow (B2) for the 6 cylinder engines to the keel cooler (B3). The size of the connections (B1) are both 45mm(1 3/4" inches). Keel cooler should be installed below the waterline far enough to avoid the aerated water close to the surface. Recessed and shielded coolers must allow for unobstructed flow around the coolers. The keel coolers should be installed so that air pockets are not present during the initial fill. Vents at all high points along the connecting of the pipes will be necessary.Keel coolers should not be fitted where they would be exposed to pounding seas or hull flexing. The bow of the vessel is not considered to be a good location whereas adjacent to the keel, where it is the strongest area of the vessel, is the preferred location. De-aeration
Air in the engine coolant can cause the following problems:* Air accelerates the corrosion within the engine water passages that can lead to high water temperatures as silt deposits on the surface of the cooler reducing the heat transfer. Premature failure of the engine can occur.* Air expands more that coolant when heated an may cause loss of coolant from the engine system through the expansion tank overflow.* In an extreme case, air will collect in one area and cause a loss of coolant flow around the cylinder block resulting in piston seizure and major engine damage.
Expansion Tank
The expansion volume in the tank must be large enough for the entire cooling system. Since the engine coolant expands about 5% between cold and hot engine operating temperatures, the expansion tank must have a volume equal to 5% of the entire cooling system volume.The plastic expansion tank supplied is just large enough for commercially available coolers used with short pipe runs and therefore in most applications a remote expansion tank with a larger capacity is recommended especially where fabricated coolers are used.When designing the larger expansion tank the following allowance should be made:* 3% to 5% of total system capacity for expansion losses* 10% of total system capacity for volume loss on hot shut down* 5% of total system capacity for working volumeThe illustration (A) shows the allowances required when designing a larger expansion tank. Engine Bleed (Vents)The engine bleed system provides a continuous flow of water through the expansion tank as a method of removing air from the engine coolant. Depending on the model of the engine there can be up to three bleed pipes which need to be connected to the top of the expansion tank. Each bleed must be connected to the expansion tank without using tee's or other fittings that would join the bleed pipes together in a common vent.
Joining the bleed pipes into a common vent will reduce the total water flow and may result in aerated water flowing back into the engine resulting in the engine overheating and possible failure.
Remote expansion tank
A remotely mounted expansion tank is recommended where longer pipe runs are required and where fabricated coolers are used. A remote cooler expansion tank kit can be fitted using the following procedure.1 Figure (A) shows draining the engine coolant (A1), cutting, removing and discarding the bleed pipes (A2), and removing the existing expansion tank (A3) and disposing of the rubber elbow (A4) at the base. 2 Mount the remote expansion tank in a position where the bottom of the unit is no lower than where the filler cap was (B1) on the original expansion tank, as shown in figure (B).3