REPAIRING THE ENGINE FRAME ORBLOCKSome engine block repairs are cost efficient, whileothers are not. The following paragraphs briefly discussbasic repairs to the block itself. Later paragraphs discussrepairs to block components.LEAKING WATER JACKETMost engine blocks that have a leaking water jacketare not worth the cost to repair. To determine if such ablock can be repaired economically, consult theappropriate MILSTD and technical manuals for theengine.WARPED CYLINDER BLOCK ORCRANKCASE FLANGESYou may use a hand surface grinder to correct smallamounts of surface warpage. Do not remove more metalthan necessary. The manufacturer’s manual will specifyhow much metal you may remove with the hand grinder.If the warpage exceeds the maximum allowed for handgrinding, send the block to the machine shop formachine grinding.WORN BOLT HOLESOver a period of time, bolt holes may becomeoversize due to wear from threading and unthreading thefasteners. You may correct a worn bolt problem by oneof three primary methods, depending on the situation.1. If the bolt hole is slightly oversize, you may beable to simply use a larger bolt in the hole, if such use isauthorized for the component the bolt fastens down.2. If enough metal remains around the hole, youmay be able to install a helicoil. Check the helicoilinstallation instructions and appropriate technicalmanuals to determine whether or not a helicoil isacceptable.3. You may also till the hole with weld metal andthen drill and tap a new hole.Whatever method you use to correct the problem,always check the bolt and bolt hole for proper fit.INSPECTING, TESTING, ANDREPAIRING CYLINDER LINERSCylinder liners may become damaged or wornexcessively. The following paragraphs discuss the morecommon causes and repairs.CRACKED, BROKEN, AND DISTORTEDLINERSYou should suspect one or more cylinder linerswhenever you notice one of the following indications:l Excessive water in the lubricating oill An accumulation of water in one or morecylinders of a secured enginel An abnormal loss of water in the cooling systeml High cooling water temperature or fluctuatingpressure (caused by combustion gases blowinginto the water jacket)l Oil in the cooling waterWhen you suspect that a liner is cracked, try tolocate the cracks visually. If you cannot locate the cracksvisually, use another testing method, such as the waterpressure test or air pressure test described earlier. Tocheck liners with integral cooling passages, plug theoutlets and fill the passages with glycol-type antifreeze.This liquid will leak from even the smallest cracks.Cracks in dry liners may be more difficult to locatebecause there is no liquid to leak through the cracks. Youmay need to use magnaflux equipment or penetratingdye to locate these cracks.CausesCylinder liners may crack because of poor cooling,improper fit of piston or pistons, incorrect installation,foreign bodies in the combustion space, or erosion andcorrosion. Improper cooling, which generally resultsfrom restricted cooling passages, may cause hot spots inthe liners, resulting in liner failure due to thermal stress.Scale formation on the cooling passage surfaces of linersmay also cause hot spots; wet liners are subject to scaleformation. You may remove the scale by following theprocedures outlined in chapter 233 of the Naval Ships’Technical Manual (NSTM).Proper cooling of dry liners requires clean contactsurfaces between the liners and the cylinder block.Particles of dirt between these surfaces cause air spaces,which are poor conductors of heat. Films of oil or greaseon these mating surfaces also resist the flow of heat.Distortion, wear, or breakage may result if a liner isnot properly seated. Causes of improper liner seatingmay be metal chips, nicks, or burrs, or improper fillets,In figure 3-3 an improper fillet on the cylinder deckprevents the liner from seating properly. To correct an3-3
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