HeatExchangers,OilCoolersandAirChargeCoolersA heat exchanger usually consists of a casing with a core (tube stack), which is the actual heat exchanger. The oil coolerusually has a smaller core and is sometimes an integral part of the engine heat exchanger.The heat exchanger and coolers should be serviced every season. However, it is stressed that, depending on operatingconditions, this period may have to be reduced. Although the coolant temperatures of new engines cease to fluctuateafter a short period of operation, the stabilized (normal operating) temperatures will vary slightly from engine to enginebecause of design tolerances, installation and hull variations. once the normal operating temperature has beenestablished for a particular engine, any excessive rise in temperature should be considered abnormal and immediatelyinvestigated. If a cooling system problem is suspected (or confirmed) the following guidelines will provide a means forisolating the cause.1.Check the coolant level in the header tank and ensure the proper pressure cap is beingused (7 psi or .492 kgf/cm2). The coolant in an operating or recently stopped engine is very hotand under pressure. If the filler pressure cap is suddenly removed the liquid may spurt andcause injury by scalding. Always stop an engine and allow it to cool before removing the cap.Once cool, loosen the cap slowly to relieve the pressure.2.Check the sea cock and strainer for obstructions - clean where necessary.3.Check the sea water pump impeller-renew if damaged. Ensure that no pieces of the impeller (if broken) havepassed into the connecting pipes (i.e., inlet and outlet) because, if so, they could restrict water flow.4.Check all heat exchangers (coolers) for obstructions within the cooling core tubes on the sea water side. Once theend cap and/or plates are removed, any minute scaling within the core tubes can be removed by passing a rod(slightly smaller than the internal bore) through the tubes. Do not use excessive force when pushing the rodthrough the tubes.If the tubes are so clogged that a rod can not be passed through them, the core will have to be removed from itscasing and boiled in a caustic soda solution. Commercial cooling system cleaners can be used for this purpose,providing they are recognized as being acceptable by the heat exchanger manufacturer. Reassemble with newgaskets, seals and "O" rings.If a reduced power and/or excessive smoke condition exists in addition to an Increase in coolant temperature with aturbo charged engine having an air charge cooler (Inter cooler), check the inter cooler and, if necessary, clean asdescribed for heat exchangers.5.Check - especially if the engine was operated in muddy or silty water- the exhaust manifold outlet elbows and theexhaust water injection connections for mud or silt restrictions.6.Oil Coolers - both engine and gear box - can also effect engine coolant temperatures. Oil coolers should bechecked and cleaned as described for heat exchangers.7.It is particulary important for TV8.510 marine engines to check the last cooler in the sea water system - usually thegear box oil cooler - for water flow restrictions. This cooler should be checked any time there is suspicion of ahigher than normal temperature and, in addition, it should be checked at least yearly with seasonal weekendcruising and twice yearly with extended cruises.-55-
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