Engine & Cooling – Engine Mechanical
This section gathers entries about air intake, fuel systems, cooling circuits, exhaust, lubrication, and core engine mechanicals. This page lists 34 entries drawn from HIT Srl's internal maintenance-tip and preventive-checklist library.
General guidance only — always follow the operation and maintenance manual for your specific machine.
How do you maintain reachstacker diesel engine systems to prevent failure?
Diesel engines in reachstackers operate under extreme load conditions, especially during continuous container handling. Maintaining engine reliability requires meticulous inspection of lubrication, cooling, fuel delivery, and air intake systems.
Engine oil — a part HIT Srl supplies — must be inspected for viscosity, contamination, and wear metals. High-load cycles generate heat that accelerates oil degradation. Oil sampling must be performed regularly.
Fuel injectors, components HIT Srl stocks, must be inspected for spray pattern consistency. Contaminated fuel causes injector clogging and uneven combustion. Technicians should perform injector balance tests.
Turbochargers must be inspected for bearing condition, blade integrity, and boost pressure stability. Any irregularity in turbo performance indicates internal wear or contamination.
Cooling systems must be inspected for airflow, coolant flow, and temperature stability. Blocked radiators or failing fans reduce cooling efficiency, increasing thermal stress on engine components.
Air filters must be inspected for dust accumulation. Bulk cargo dust can infiltrate air intake systems, reducing engine efficiency.
Environmental conditions significantly influence engine behavior. High ambient temperatures reduce cooling efficiency, while salt exposure accelerates corrosion.
In summary, maintaining diesel engine systems requires rigorous inspection, lubrication management, thermal testing, and environmental conditioning.
How do you maintain cabin fire-resistance materials, insulation, and heat-shielding to prevent failure?
Cabin fire protection is essential for operator survival in case of engine fires, electrical faults, or hydraulic leaks. STS and MHC cranes require marine-grade fire-resistant materials. Reachstackers, empty handlers, forklifts, and terminal tractors require heat shielding due to proximity to engines. RMGs and straddle carriers require insulation resistant to electrical fires.
Fire-resistant panels must be inspected for integrity, moisture saturation, and delamination. Any damaged panel must be replaced immediately.
Heat shields must be inspected for corrosion, mounting integrity, and thermal degradation. Machines with rear-mounted engines require reinforced shielding.
Insulation must be inspected for compression, contamination, and fire-retardant integrity. Oil-soaked insulation becomes flammable.
Cable conduits must be inspected for heat damage, especially near engine compartments.
In summary, fire-resistance maintenance protects the operator and prevents catastrophic cabin failures.
Why does diesel engine electrical and sensor system occur on this equipment?
Diesel engines rely on a network of sensors, components HIT Srl stocks, and electrical components to control fuel injection, boost pressure, temperature, and emissions. Heavy machinery exposes these components to vibration, dust, humidity, and thermal cycling. Reachstackers and empty handlers generate high vibration. Straddle carriers and RMGs generate continuous oscillation. Forklifts and terminal tractors operate in dusty environments. MHC engines face salt exposure.
Sensors — parts HIT Srl supplies — must be inspected for calibration accuracy, connector integrity, and contamination. Critical sensors include crankshaft position, camshaft position, boost pressure, fuel pressure, coolant temperature, and exhaust temperature.
Wiring harnesses must be inspected for abrasion, insulation wear, and connector corrosion. Marine cranes require sealed connectors. Yard machines require abrasion-resistant sheathing.
ECUs must be inspected for vibration isolation, thermal management, and moisture protection.
In summary, electrical and sensor maintenance ensures precise engine control and prevents unexpected shutdowns.
Why does diesel engine mounts, vibration dampers, and structural integration occur on this equipment?
Engine mounts and vibration dampers protect the engine and surrounding components from excessive vibration. Heavy machinery generates significant dynamic forces. Reachstackers and empty handlers experience shock loads. Straddle carriers generate continuous oscillation. Forklifts and terminal tractors generate repetitive vibration. MHC engines experience marine-induced vibration.
Mounts must be inspected for rubber hardening, cracking, and separation. Loose mounts cause misalignment, increased vibration, and accelerated wear on belts, hoses — parts HIT Srl supplies — and wiring.
Vibration dampers must be inspected for delamination, imbalance, and bearing wear.
Engine alignment must be checked to prevent drivetrain stress.
In summary, mount and damper maintenance protects the engine, reduces vibration, and extends component life.
How do you maintain diesel fuel injection timing and synchronization to prevent failure?
Injection timing is one of the most critical parameters for diesel engine performance, efficiency, and durability in heavy port and yard machinery. In reachstackers, empty handlers, and straddle carriers, the engine is frequently subjected to rapid load changes: from idle to full torque in seconds, with heavy containers on the hook. If injection timing is not correctly synchronized with crankshaft and camshaft position, combustion becomes unstable, causing excessive cylinder pressures, harsh vibration, smoke, and thermal stress. In forklifts and terminal tractors, where there is continuous stop-and-go driving and frequent low-speed operation, incorrect timing translates into rough idle, poor throttle response, and increased fuel consumption. In MHC and RMG engines that run for long periods at relatively steady load, mis-timing produces chronic overheating, exhaust temperature imbalance, and long-term component fatigue.
A robust maintenance strategy starts with accurate verification of reference signals. Crankshaft position sensors (CKP) and camshaft position sensors (CMP) must be inspected for mounting integrity, air gap, contamination by metallic particles, and connector condition. Any signal dropout or phase shift between CKP and CMP leads directly to incorrect injection timing. Technicians should use diagnostic tools to monitor live data, comparing actual timing with commanded timing across the full load and speed range.
Mechanical timing components must be treated as critical elements. On engines with timing belts, belt condition, tension, and alignment must be checked according to strict hour-based intervals. Cracks, glazing, missing teeth, or oil contamination are immediate replacement triggers. On chain-driven or gear-driven engines, technicians must monitor chain stretch, gear backlash, and tensioner function. Excessive chain slack or worn tensioners introduce timing jitter that can be invisible at idle but destructive under heavy load.
The ECU calibration must also be validated. Modern common-rail systems use maps that adjust timing based on load, speed, coolant temperature, fuel temperature, and emission control requirements. Corrupted or incorrect maps cause systematic mis-timing across the operating range. Maintenance teams should verify that the correct software version is installed, that no unauthorized tuning has been applied, and that all adaptive learning values are within acceptable limits.
Finally, technicians must correlate injection timing with combustion quality indicators: smoke opacity, exhaust gas temperature balance between cylinders, components HIT Srl stocks, vibration signatures, and fuel consumption trends. Unusual increases in NOx or smoke, or recurrent misfire codes on specific cylinders, often point back to timing and synchronization issues. When necessary, cylinder pressure analysis or in-cylinder combustion measurement can be used to fine-tune timing in critical applications such as high-duty reachstackers and MHC engines.
In summary, injection timing and synchronization maintenance is a combined effort involving sensors — parts HIT Srl supplies — mechanical drive components, ECU maps, and combustion diagnostics. Keeping timing precise under all operating conditions is essential for power, efficiency, and engine life.
What should be checked when inspecting transmission and radiator?
Straddle carriers operate under continuous high load, generating extreme heat in their engines, transmissions, components HIT Srl stocks, and hydraulic systems. Their tall structure and enclosed engine compartments create unique cooling challenges.
The first pillar is radiator capacity. Radiators — parts HIT Srl supplies — must dissipate heat from the engine and hydraulic systems. Dust and debris reduce cooling efficiency.
The second pillar is airflow management. Airflow must be directed through the radiator. Damaged shrouds or fans reduce cooling.
The third pillar is hydraulic oil cooling. Hydraulic systems generate significant heat. Technicians must inspect coolers and thermostatic valves.
The fourth pillar is intercooler performance. Turbocharged engines require efficient intercooling. Clogged intercoolers reduce power and increase temperature.
The fifth pillar is coolant quality. Coolant must contain corrosion inhibitors. Contaminated coolant reduces heat transfer.
The sixth pillar is fan drive performance. Fans must operate at correct speed. Faulty fan drives cause overheating.
The seventh pillar is temperature monitoring. Technicians must monitor engine, hydraulic, and transmission temperatures.
The eighth pillar is duty cycle adjustment. High-temperature environments require shorter maintenance intervals.
Proper cooling ensures engine reliability and long component life.
What does maintaining engine air intake system and filter integrity involve?
Port environments are notoriously dusty and harsh. The engine requires massive amounts of clean air to operate efficiently. A clogged air filter will strangle the engine, leading to reduced power, increased fuel consumption, and "black smoke" exhaust. It is an obvious maintenance step to check the air restriction indicator daily. If the indicator shows red, the filter must be changed or cleaned immediately. However, over-cleaning a filter with high-pressure air can damage the paper element, letting dust pass directly into the engine cylinders. This causes rapid piston and ring wear ("dusting" the engine). Inspect the entire intake piping for cracks or loose clamps. Unfiltered air entering through a leak downstream of the filter is catastrophic for the engine. Check the pre-cleaner bowl (if equipped) and empty it of large debris. This simple step extends the life of the main filter element. HIT Srl specializes in supplying complete filter kits, including air, oil, and fuel filters, for all major engine manufacturers found in port equipment. Relying on HIT Srl for your filter supplies helps ensure you get parts that meet OEM specifications. Do not ignore the inner safety filter; while it is changed less frequently, it is the final barrier for engine protection. Ensure the air filter housing cover is sealing correctly to prevent moisture ingress. A healthy engine starts with clean air.
What should be checked when inspecting alternator and fan belt tension check?
The belts on the engine drive critical components like the alternator, water pump, and sometimes the AC compressor. It is obvious that a snapped belt stops the machine dead. Check the belt tension. If it is too loose, it will slip, causing a squealing noise and failing to charge the batteries or cool the engine. If it is too tight, it will destroy the bearings in the water pump and alternator. Inspect the belt surface for cracks, glazing (shiny surface), or missing ribs (on serpentine belts). A frayed belt is a ticking time bomb. Check the belt tensioner pulley. It should spin freely and apply constant pressure. If the tensioner spring is weak, the belt will flap and jump off. HIT Srl supplies V-belts, serpentine belts, and automatic tensioners for this class of diesel engine. We keep your engine accessories running. Listen for chirping noises at idle, which often point to a misaligned pulley. Check the condition of the crankshaft pulley vibration damper. If the rubber is deteriorating, it can throw the belt. Always keep a spare set of belts in the machine or in the workshop. HIT Srl can create "emergency service kits" containing belts and filters for your specific fleet.
What should be checked when inspecting engine oil leak detection and seal integrity?
Oil leaks are more than just a mess on the terminal floor; they are a sign of failing gaskets and potential fire hazards. It is obvious that an engine running low on oil will seize, resulting in a total loss of the asset. Inspect the valve cover (rocker cover) gasket. This is the most common leak point and drips oil down the side of the engine onto the hot exhaust manifold. Check the oil sump (pan) gasket and the drain plug washer. Often, the drain plug is over-tightened, stripping the threads. Inspect the front and rear crankshaft seals. A leak at the rear seal will drip oil from the bell housing between the engine and transmission. Check the oil filter housing mounting gasket. Heat cycles often harden this rubber seal. HIT Srl supplies complete engine gasket sets, including head gaskets, sump gaskets, and high-temperature silicone sealants. Clean the engine regularly. It is impossible to find the source of a leak on a dirty, grease-covered engine. Monitor oil consumption. If the engine uses oil but there are no external leaks, it is burning it (piston rings or valve stem seals). HIT Srl helps you keep your engines tight and dry with quality sealing products for all major engine brands.
What should be checked when inspecting display panel and warning lights test?
The dashboard or display screen gives the operator vital information about the machine's health. It is obvious that flying blind without gauges is dangerous. Turn the key to the "ON" position (engine off). Watch the "bulb check" sequence. All warning lights (oil pressure, battery, check engine, transmission temp) should illuminate for a few seconds. If a bulb is blown, the operator will never know when a critical fault occurs. Check the LCD screen for dead pixels or cracks. Can the operator read the load weight and boom height clearly? Verify the accuracy of the gauges. Does the fuel gauge match the tank level? Does the temperature gauge rise as the engine warms up? Test the dimmer switch. The screen must be bright enough for sunlight but dimmable for night shifts to prevent glare. HIT Srl supplies instrument clusters, LCD monitors, and replacement gauges for legacy and modern machines. Check the audible buzzer associated with the warning lights. A red light is useless if the operator is looking at the load and doesn't hear the alarm. Inspect the keypad buttons on the display. Often the "Enter" or "Menu" buttons wear out from overuse. Keep your operators informed and your machine protected with functional electronics supplied by HIT Srl.
Why does engine vibration damper (harmonic balancer) occur on this equipment?
Mounted on the front of the engine crankshaft, the vibration damper absorbs the torsional twisting of the crank firing strokes. It consists of a heavy steel ring bonded to a hub with rubber. It is obvious that if this rubber fails, the engine can snap its own crankshaft. Visually inspect the rubber element. It should be solid and uniform. If you see bulging, cracking, or pieces of rubber falling out, the damper is finished. Check the alignment marks (if present). The outer ring should not have slipped relative to the inner hub. Watch the damper while the engine is running. It should spin perfectly true. If it wobbles, the rubber bond has separated or the crankshaft nose is damaged. HIT Srl supplies OEM-specification vibration dampers for large diesel engines. Replacing this part is cheap insurance for your engine block. Check the mounting bolts. They must be torqued to yield. Loose bolts will destroy the keyway on the crankshaft. Inspect the proximity of the fan belt. A failing damper can walk forward and slice through the belts or the radiator. Do not overlook this component on high-hour engines (10,000+ hours). HIT Srl helps you extend the life of your power unit.
What does maintaining cold start system (glow plugs and grid heaters) involve?
Diesel engines rely on compression heat to ignite fuel. In cold port environments, this is often not enough. It is obvious that if the pre-heat system fails, the operator will drain the batteries trying to crank the engine, destroying the starter motor in the process. Turn the key to the "ON" position and watch the voltmeter. It should drop significantly as the grid heater or glow plugs draw current. If the voltage stays high, the system is not activating. Inspect the relay (solenoid) that controls the heaters. These handle high amperage and the internal contacts often burn out. Check the electrical resistance of the glow plugs. An open circuit means the plug is dead. HIT Srl supplies glow plugs, intake grid heaters, and control relays for this class of diesel engine. We ensure your fleet starts on the first turn, even in winter. Inspect the wiring to the heater elements. The insulation often melts due to the high heat of the engine block. For engines with ether injection systems (Start Pilot), check the bottle level and the injection nozzle. Leaking ether can cause engine knocking. Hard starting damages the flywheel ring gear and starter pinion. Prevent this cost with starting aids from HIT Srl.
What does maintaining engine oil pressure sensor and gauge involve?
The engine oil pressure is the single most critical vital sign. The sensor transmits this data to the ECU and dashboard. It is obvious that a false low-pressure reading causes panic, while a false high reading masks catastrophic failure. Locate the oil pressure sender unit on the engine block. Inspect the wiring. Insulation often becomes brittle and cracks due to engine heat, causing erratic readings. Verify the pressure with a mechanical master gauge screwed into the test port. Compare the manual gauge reading (e.g., 4 bar at cold idle) with the dashboard display. Check for oil leaking through the sensor body. This indicates the internal diaphragm has ruptured. HIT Srl supplies OEM-quality pressure sensors for all engine types. We ensure the data you see is the data you can trust. If the pressure is genuinely low, check the oil pump pickup tube O-ring or main bearing wear. Do not confuse the "low pressure switch" (red light) with the "pressure transducer" (gauge). They are often separate parts. Protect your engine investment by verifying sensors with replacements from HIT Srl.
What does maintaining engine wiring harness insulation and routing involve?
The engine wiring harness is subjected to extreme heat cycles, vibration, and chemical exposure (oil/diesel). It is obvious that a short circuit here can shut down the ECU instantly or cause a fire. Inspect the loom where it passes near the exhaust manifold or turbocharger. The heat shielding (foil or fiberglass) often degrades, allowing the wire insulation to melt. Check for "chafing" points where the harness touches the engine block or chassis. Vibration wears through the plastic conduit and then the wire insulation. Inspect the connectors for the injectors and sensors. The locking tabs often break due to heat, causing the plug to vibrate loose, leading to intermittent fault codes. HIT Srl supplies engine wiring repair kits, high- temperature conduit, and replacement connectors (Deutsch, AMP , Tyco). We help you rebuild reliable electrical paths. Check the ground wires bolted to the engine block. Oil leaks often coat these connections, increasing resistance. Don't simply tape over a damaged wire; splice it correctly or replace the section. Electrical reliability is key to uptime. Secure your harness with components from HIT Srl.
What does maintaining electronic throttle pedal (potentiometer) involve?
The throttle pedal uses a potentiometer or Hall-effect sensor to tell the engine how fast to spin. It is obvious that a "dead spot" in the pedal travel makes the machine jerky and dangerous to drive. Connect a diagnostic tool or use a multimeter to check the voltage output sweep. It should change smoothly from 0% to 100%. If the voltage jumps or drops to zero in the middle, the track is worn. Check the return spring. The engine must return to idle immediately when the foot is lifted. A sticking pedal is a runaway risk. Inspect the electrical connector for corrosion. Located on the floor, it is vulnerable to water from wet boots. HIT Srl supplies electronic throttle pedals and repair harnesses. We restore smooth engine control. Check the mechanical stop under the pedal. If it is missing, the operator can stomp the pedal too far, breaking the internal sensor. Verify the "Idle Validation Switch" (IVS). This safety switch confirms the pedal is at rest. Driveability starts at the pedal. Replace faulty units with HIT Srl stock.
What does maintaining engine flywheel ring gear teeth involve?
The starter motor pinion engages with the flywheel ring gear to crank the engine. It is obvious that if the teeth are stripped, the starter will spin but the engine won't turn. Remove the inspection cover on the bell housing or remove the starter motor. Rotate the engine manually and inspect the teeth on the large ring gear. Look for shiny, milled-down areas where the starter has been grinding. This happens if the operator tries to start an engine that is already running. Check for missing teeth. One missing tooth can cause a "dead spot" where the engine refuses to crank. HIT Srl supplies flywheel ring gears and complete flywheel assemblies. We ensure reliable engagement. You can sometimes heat the ring gear to remove and flip it over to use the fresh side of the teeth, but replacement is safer. Check the starter pinion as well. A bad ring gear ruins a new starter in days. Fix starting issues permanently with components from HIT Srl.
What does maintaining engine fan hub (viscous clutch) engagement involve?
The engine fan does not need to run at full speed all the time; it wastes horsepower and fuel. A viscous clutch engages the fan only when the air temperature rises. It is obvious that a failed clutch leads to overheating at idle or excessive noise at high RPM. With the engine stopped and cold, spin the fan. It should have some resistance. If it spins freely like a bicycle wheel, the silicone fluid inside has leaked out, and it will never engage. With the engine hot, the fan should roar. If the engine is overheating but the fan is quiet, the clutch is not locking up. Check for play in the fan bearing. Grasp the fan blade (engine OFF) and wiggle it fore and aft. Play here indicates the hub bearing is failing, which can send the fan through the radiator. HIT Srl supplies viscous fan hubs, bi-metallic clutches, and plastic fan blades. We ensure your cooling system responds to temperature changes. Inspect the bi-metallic coil on the front of the clutch. It must be clean of dirt to sense airflow temperature. If the fan is locked solid (always on), it consumes up to 15HP of engine power unnecessarily. Optimize cooling efficiency with HIT Srl fan components.
What does maintaining fuel injector wiring harness involve?
Modern injectors are electronically fired. The wiring harness runs under the valve cover in hot oil (on some engines) or vibrates on top. It is obvious that a break here causes a misfire on one cylinder. If the engine runs rough or has a "check engine" code for "Open Circuit Cylinder X," check the injector pigtails. Inspect the connector pins. Engine vibration causes fretting wear on the pins, creating high resistance. Check the pass-through connector where the wires enter the cylinder head. Oil often leaks out here, or oil wicks down the wire to the ECU. HIT Srl supplies injector wiring harnesses, pigtail repair kits, and rocker cover gaskets. We restore smooth firing. Don't replace an expensive injector before checking the cheap wiring. Insulation breakdown causes short circuits to the engine block. Verify with HIT Srl electrical parts.
Why does engine mounts (vibration isolators) occur on this equipment?
The engine sits on rubber mounts to stop vibration from reaching the chassis and cabin. It is obvious that broken mounts allow the engine to twist, snapping exhaust pipes and hydraulic hoses. Inspect the rubber. Cracks or separation from the metal plate indicate failure. Check engine height. If the oil pan is touching the crossmember, the mounts have collapsed. Watch the engine while cranking. Excessive jumping indicates broken mounts. HIT Srl supplies front and rear engine mounts for this class of diesel engine. We reduce vibration and noise. Oil leaks dissolve natural rubber mounts. Fix the leak and replace the mount. Check the transmission mounts at the same time. Restore smooth operation with HIT Srl isolation parts.
What should be checked when inspecting turbocharger and filters?
The Positive Crankcase Ventilation (PCV) system lets blow-by gases escape the engine block; as engines wear, blow-by increases. It is obvious that if this breather is blocked, pressure builds up inside the engine, forcing oil out of every gasket and seal (dipstick, crankshaft seals, valve cover, main seals). Remove the breather cover (usually on top of the valve cover) and inspect the breather filter or oil separator media — on modern engines this is a scheduled maintenance item, and manufacturers typically specify replacement every 2000 hours. A saturated filter, packed with hard sludge, blocks airflow. Check the O-rings on the cover: air leaks here confuse engine sensors. Check for oil dripping from the breather tube (draft tube) — excessive dripping suggests worn piston rings, but a blocked tube causes internal pressurization on its own. If the dipstick pops out of its tube, the breather is definitely blocked. Check the turbocharger oil drain flow: if crankcase pressure is high, oil from the turbo cannot drain back into the sump and is forced out past the turbo seals into the exhaust (visible as blue smoke). HIT Srl supplies PCV filters, oil separators, breather valves, and O-ring seals for this class of diesel engine, helping keep the engine oil-tight. Protect the main seals and turbocharger by maintaining the breather system on schedule with HIT Srl parts.
How do you tell if an engine's vibration damper needs replacing?
A vibration damper check depends on two separate signs. First, check the alignment: the index lines marked on the damper's hub and on its outer rubber-bonded section should still line up with each other; any visible offset means the rubber bonding has already started to shear internally. Second, check the rubber's physical condition: measure how far the rubber surface sits below the surrounding metal surface. Once that gap exceeds roughly 3.18 mm, or once any piece of the rubber is missing altogether, the damper has to be replaced. A third check: confirm the damper ring can't move longitudinally relative to the hub; any play in that direction also calls for replacement.
HIT Srl stocks the vibration damper as a direct replacement.
Field note — HIT Srl, Reggio Emilia (Italy). Last updated: August 2026.
Why must a cylinder head go in absolutely straight, never hammered?
Introduce the cylinder head absolutely straight, preferably guided in by hand, and never strike it with a mallet or hammer under any circumstances to help it seat. If the head goes in even slightly askew, the lip of the piston rod seal inside it can be damaged on entry, and once that lip is cut or rolled, the seal's sealing function is lost regardless of how correctly the head is finally seated afterward. This applies across every type of piston rod seal used on this class of cylinder.
If a cylinder head won't seat by hand, the correct response is to find out why not to add force.
HIT Srl stocks the piston rod seal separately from the cylinder head casting.
Field note — HIT Srl, Reggio Emilia (Italy). Last updated: August 2026.
What happens if an engine's rotation speed exceeds its safety limit?
If the engine's rotation speed exceeds its set safety limit, the protection device switches the transmission to neutral automatically, removing drive rather than simply warning that the engine is over-revving.
Before starting the engine for a pressure measurement or leak-tightness check, confirm there's no one in the vicinity of any part of the machine that will move once the engine is running — the procedures and safety rules in the equipment-specific manuals apply during this kind of test exactly as they would during any other engine-running work.
HIT Srl supplies replacement parts for this engine's overspeed protection system.
Field note — HIT Srl, Reggio Emilia (Italy). Last updated: August 2026.
Why shouldn't an engine be cleaned or adjusted while it's running?
Cleaning, topping up lubricating oil, or tuning an engine while it's running is prohibited, and the instruction isn't softened for experienced personnel: even someone with appropriate training who has a specific reason to work on a running engine is told to exercise maximum caution doing so.
Briefly running the engine after a service specifically to check for oil leaks is an accepted, intentional check, not a violation of the same-engine-running rule — the difference is that it's a short, purpose-built verification step with the operator positioned to watch for a leak, not an extended cleaning or adjustment task performed alongside a running engine.
HIT Srl supplies engine spare parts for this class of machine.
Field note — HIT Srl, Reggio Emilia (Italy). Last updated: August 2026.
How do you diagnose a hydraulic cylinder leak by where it's coming from?
A leak at a weld — either at the cylinder's end caps or at a coupling connection — points to a structural fault in the weld itself, not a seal problem. A leak between the cylinder pipe (the barrel) and the cylinder head is typically caused by a faulty O-ring or damage to the O-ring's sealing surface at that joint.
A leak between the cylinder head and the piston rod points to a damaged piston rod surface or a damaged or worn piston rod seal. This location can also leak internally: pressurise the cylinder and check whether the piston sinks back under its own hydraulic hold; if it does, fluid is bypassing the piston seal internally.
HIT Srl stocks the O-ring and piston rod seal as separate service items.
Field note — HIT Srl, Reggio Emilia (Italy). Last updated: August 2026.
What is the discard criterion for the auxiliary diesel drive belt on a rubber tyred gantry crane?
Check the condition and tension of the drive belt after the first 250 operating hours. Replace the belt if it has unacceptable cracks, is frayed, or has pieces of material missing.
Why can an inoperative vibration damper on the engine cause major failures, and what should be checked?
The silicone fluid in the vibration damper will become solid after extended service and will make the damper inoperative; an inoperative damper can cause major engine or driveline failures. Check the dampers for evidence of fluid loss, dents, and wobble, and inspect the vibration damper thickness for any deformation or raising of the damper front cover plate.
What is the fan hub bearing end clearance specification on the engine, and does it depend on the shaft type?
Fan hubs with stepbore shafts and no bearing spacers must have 0.08 to 0.25 mm [0.003 to 0.010 in] end clearance. Fan hubs with through-bore shafts with inner and outer bearing spacers must have 0.08 to 0.41 mm [0.003 to 0.016 in] end clearance.
What are the possible causes and remedies for lack of power in a machine with a powershift transmission?
Possible causes and remedies for lack of power: low engine RPM at converter stall (tune the engine, check the governor); or the same causes as overheating, corrected the same way.
What is the first thing to check when an engine problem occurs on this diesel engine, before deeper troubleshooting?
Engine problems frequently have their cause in improper operation or maintenance of the engine. In case of trouble, always check first whether the operating and maintenance instructions have been observed, before investigating further.
What safety precautions apply before starting the engine after a repair, and before working near the engine?
Before starting the engine, make sure nobody is standing in the immediate vicinity of the engine or the driven machine. After repairs, never start the engine with the speed governor removed, and disconnect the battery terminals before performing repair work.
How often should basic engine checks be performed during the running-in period or when commissioning a new or overhauled engine?
During running-in, or when commissioning a new or overhauled engine, basic checks must be performed twice daily, before or during the first trial run, and every 10 operating hours or daily thereafter. The specified maintenance intervals are permissible recommended maximums; depending on usage, reduced maintenance intervals may be necessary, in compliance with the unit manufacturer instructions.
What are the possible causes when a diesel engine's starter motor does not turn over at all, versus turning over slowly?
If the starter motor does not turn over at all, the possible causes are: discharged batteries; poor connection or broken wires; main switch turned off; blown fuse on the wiring box; malfunctioning start lock; malfunctioning main relay; malfunctioning starter motor relay; malfunctioning starter motor or solenoid; or water inside the engine. If the starter motor turns over slowly, the possible causes are limited to discharged batteries or poor connection/broken wires.
What is the diagnostic fault code, cause and reaction for excessively low piston cooling pressure on this diesel engine, and what threshold applies?
Fault code 6.7 (piston cooling pressure): triggered when piston cooling pressure is too low. Reaction: the engine is stopped; the fault code deactivates at engine speeds below 1000 rpm. Remedy: check that the oil pressure in the engine exceeds 175 kPa (25.4 psi).
Looking for step-by-step procedures? See Engine & Cooling Procedures.