Yanmar cylinder head gaskets

How can you identify a faulty Yanmar cylinder head gasket? The symptoms below may indicate a damaged cylinder head gasket, but they are not a definitive diagnosis. Overheating, a clogged heat exchanger, a faulty water pump, a blocked exhaust elbow or a defective injector can produce similar signs. ●      Bubbles in the cooling circuit: combustion gases may pass into the water circuit. On an engine with a heat exchanger, this can create excess pressure or visible bubbles in the expansion tank. ●      Persistent white exhaust smoke: water or coolant may enter a cylinder and vaporise. However, light vapour during a cold start is not enough to conclude that the cylinder head gasket has failed. ●      Abnormal overheating: a temperature rise under load, with no visible external leak, may come from the cylinder head gasket, but also from a water pump, thermostat, heat exchanger or seawater circulation fault. ●      Emulsified oil or a “mayonnaise” appearance: the presence of water in the engine oil is a serious sign. It can come from the cylinder head gasket, but also from a heat exchanger, an oil cooler or water entering through the exhaust. ●      Unexplained drop in coolant level: on an indirectly cooled engine, regular loss with no visible leak should raise suspicion of an internal leak or transfer towards the exhaust. ●      Difficult starting or low compression: a gasket failure between two cylinders or towards the outside can cause compression loss and irregular running. ●      Black marks or seepage at the gasket face: combustion deposits or visible leaks between the block and cylinder head may indicate a loss of sealing. What are the golden rules for reliable reassembly? ●      Identify the correct gasket before installation: compare the old and new gasket: bores, oil passages, water passages, thickness marks, notches, holes and reference. ●      Check cylinder head flatness: a removed cylinder head must be checked with a straightedge and feeler gauges. A warped cylinder head can quickly destroy a new gasket. ●      Check the condition of the block: the block gasket face must be clean, free from scratches and corrosion, and without deposits around the water passages. ●      Clean the gasket faces carefully: remove old gasket residue with a suitable tool, without gouging or scratching aluminium or cast iron. Aggressive abrasives should be avoided as they can alter flatness. ●      Do not fit the gasket upside down: check the markings, installation direction and alignment of all passages before fitting the cylinder head. ●      Follow the manufacturer’s tightening procedure: use a calibrated torque wrench and follow the tightening order, torque values and any specified angles in the Yanmar workshop manual. ●      Replace bolts or studs if the manual requires it: some engines may require the cylinder head bolts to be replaced or their condition to be checked precisely. ●      Do not assume retightening after running-in is always required: on some older engines, checking or retightening may be specified after heating. On others, it must not be done. Always follow the manufacturer’s manual procedure. ●      Bleed and check the cooling system after reassembly: fill the circuit correctly, bleed air if necessary and monitor the temperature during the first tests. What are the compatibilities and references for Yanmar cylinder head gaskets? The references below come from the DAM Marine catalogue for Yanmar cylinder head gaskets. Some are Yanmar OEM references, while others are DAM/ORB catalogue references. Before ordering, always compare the reference, engine, gasket thickness, installation marks and, where possible, the engine serial number.   Displayed reference Reference type Listed applications Points to check 119415-01330 OEM Yanmar Joint de culasse Yanmar — application à confirmer selon moteur Check the exact model and serial number ORB63056 DAM/ORB catalogue reference 6LP-STE, 6LP-STP, 6LP-STZE, 6LP-STZE1, 6LPA-STE, 6LPA-STP, 6LPA-STZP — thickness 1.0 mm Check gasket thickness and identification marks ORB63057 DAM/ORB catalogue reference 6LP-STE, 6LP-STP, 6LP-STZE, 6LP-STZE1, 6LPA-STE, 6LPA-STP, 6LPA-STZP — thickness 1.1 mm, Mark 3 Check notches/marks and original thickness ORB63053 DAM/ORB catalogue reference 6LP-DTE, 6LP-DTP, 6LP-DTZE, 6LP-DTZE1, 6LP-DTZP, 6LP-DTZP1, 6LPA-DTE, 6LPA-DTP, 6LPA-DTZE, 6LPA-DTZP — thickness 1.2 mm Do not confuse the 6LP-DT and 6LP-ST versions ORB63058 DAM/ORB catalogue reference 6LP-STE, 6LP-STP, 6LP-STZE, 6LP-STZE1, 6LPA-STE, 6LPA-STP, 6LPA-STZP — thickness 1.2 mm Check the engine version and gasket thickness ORB63054 DAM/ORB catalogue reference 6LP-DTE, 6LP-DTP, 6LP-DTZE, 6LP-DTZE1, 6LP-DTZP, 6LP-DTZP1, 6LPA-DTE, 6LPA-DTP, 6LPA-DTZE, 6LPA-DTZP — thickness 1.3 mm Check the thickness marks before ordering ORB63055 DAM/ORB catalogue reference 6LP-DTE, 6LP-DTP, 6LP-DTZE, 6LP-DTZE1, 6LP-DTZP, 6LP-DTZP1, 6LPA-DTE, 6LPA-DTP, 6LPA-DTZE, 6LPA-DTZP — thickness 1.4 mm Check original thickness, piston protrusion and gasket marks ORB63023 DAM/ORB catalogue reference Yanmar 1GM Do not confuse 1GM and 1GM10 ORB63024 DAM/ORB catalogue reference Yanmar 1GM10 Check the engine type and serial number ORB63028 DAM/ORB catalogue reference Yanmar 2GM, 2GMF Do not confuse with 2GM20 / 2GM20F ORB63029 DAM/ORB catalogue reference Yanmar 2GM20, 2GM20F Check the exact variant: F, YEU, C or other installation 124060-01331 OEM Yanmar Yanmar 2QM15 Confirm with the engine serial number 124772-01331 OEM Yanmar Yanmar 2QM20 Confirm with the engine serial number ORB63033 DAM/ORB catalogue reference Yanmar 3GM Do not confuse 3GM, 3GMF, 3GM30 and 3GM30F ORB63034 DAM/ORB catalogue reference Yanmar 3GM30, 3GM30F Check the generation and cooling type ORB63036 DAM/ORB catalogue reference / marked Yanmar on the page Yanmar 3HM, 3HMF Do not confuse with 3HM35 ORB63035 DAM/ORB catalogue reference Yanmar 3HM35 Check the 3HM35 / 3HM35F version ORB63039 DAM/ORB catalogue reference / marked Yanmar on the page Yanmar 3JH4 / 3JH5 Check the exact version: 3JH4E, 3JH5E, 3JH5AE, etc. 121370-01332 OEM Yanmar Yanmar 3QM30 Confirm with the exact engine type 119515-01331 OEM Yanmar Yanmar 3YM20 Check serial number and generation 119717-01331 OEM Yanmar Yanmar 3YM30 Check serial number and generation 129693-01341 OEM Yanmar Yanmar 4JH4 Check the exact version: 4JH4E, 4JH4-TE, 4JH4-HTE, etc. ORB63050 DAM/ORB catalogue reference Yanmar series 3JH2 : 3JH2, 3JH2BE, 3JH2E, 3JH2Z Check the exact 3JH2 variant ORB63038 DAM/ORB catalogue reference Yanmar 3JH3, 3JH3E, 3JH3CE Check the exact variant and engine generation ORB63045 DAM/ORB catalogue reference Yanmar 4JH, 4JH-HT, 4JH-HTE, 4JH-T, 4JH-TE, 4JHE Check thickness and engine version DM_MA_129573-01341 DAM reference associated with a Yanmar reference Yanmar series 4JH2 — thickness 1.3 mm Check thickness: 1.3 mm or another variant ORB63046 DAM/ORB catalogue reference Yanmar 4JH2-DTE, 4JH2-HTE, 4JH2-TE, 4JH2-UTB, 4JH2-UTE, 4JH2E — thickness 1.4 mm Do not confuse with the 4JH2 1.3 mm gasket ORB63043 DAM/ORB catalogue reference Yanmar series 4JH3-DTE / 4JH3-HTE Check the exact 4JH3 version ORB63041 DAM/ORB catalogue reference Yanmar 4JH3, 4JH3E, 4JH3CE, 4JH3ZA, 4JH3-TCE, 4JH3-TE Check the naturally aspirated or turbo version ORB63042 DAM/ORB catalogue reference Yanmar series 4JH4 Check compatibility with OEM reference 129693-01341 if necessary ORB63047 DAM/ORB catalogue reference Yanmar series 4LH — thickness 1.3 mm Check 4LH / 4LHA version and gasket thickness ORB63026 DAM/ORB catalogue reference Yanmar YSM12, YSB12, YSE12 Check the exact engine generation ORB63025 DAM/ORB catalogue reference Yanmar YSM8, YSB8, YSE8 Also listed as included in the ORB61002 decarbonising gasket set