The part is an essential component of the cabin heating system on the HOWO MAX 4X2 MC13 engine, providing a reliable interface between the engine coolant circuit and the heater core. This Cab heating connection pipe DM18 assembly ensures that warm coolant is efficiently routed to the cab heater, maintaining driver comfort in cold climates. When you choose authentic Howo Parts, this Cab heating connection pipe DM18 kit guarantees OE fitment and leak free operation. Below are detailed descriptions of every component included with this Cab heating connection pipe DM18 assembly.
The hose joint M22X1,5 DN18 is a precision machined brass or steel fitting that connects The part to the engine coolant outlet and the heater core inlet. This Cab heating connection pipe DM18 hose joint features an M22x1.5 threaded male end with a tapered sealing seat that accepts the composite sealing washer. The DN18 designation indicates a nominal inside diameter of 18mm, matching the standard hose size used in the MC13 heating circuit.
The hose joint has a barbed end with a raised bead that provides secure retention for the rubber heater hose when clamped. Two hose joints are supplied, allowing both the supply and return lines to be connected. The joint is constructed from dezincification resistant brass, preventing corrosion from coolant exposure. Proper tightening of The part hose joint to 25 Nm ensures a leak proof connection that will withstand coolant pressures up to 2.5 bar. The hose joint also includes a hexagonal body that enables easy installation with a standard wrench.
The composite sealing washer is a bonded seal with an inner diameter of 22.7mm and outer diameter of 30.0mm, made from a steel outer ring with an FPM1 rubber sealing element. This Cab heating connection pipe DM18 washer is used under the hose joint head to seal the threaded connection against coolant leakage.
Two washers are supplied, matching the two hose joints. The FPM1 rubber provides excellent resistance to hot ethylene glycol coolant at temperatures up to 150°C, maintaining its elasticity over thousands of thermal cycles. The steel ring ensures that the washer does not extrude under high clamping force. Replace this Cab heating connection pipe DM18 washer whenever the hose joint is removed, as the rubber will have taken a compression set. The washer’s dimensions are specifically designed for the M22x1.5 thread, ensuring a perfect fit.
The warm air return pipe blanking cap is a plastic or metal cap used to seal the unused port on the engine block or coolant distribution housing. This Cab heating connection pipe DM18 cap is installed when the vehicle is not equipped with a cab heater or when the heater circuit is bypassed. Two caps are supplied,
providing the option to seal both the supply and return ports. The cap is made from glass filled nylon or zinc plated steel, resistant to engine coolant and under hood temperatures. It is designed to snap or screw into place, providing a dust tight and pressure tight seal. When The part is used with the hose joints, the blanking caps are removed and stored. The caps prevent debris from entering the coolant passages during assembly and can be reused if the heater is later disconnected.
Cab heating connection pipe DM18 – genuine HOWO cabin heating hardware kit for MAX 4X2 MC13
This Cab heating connection pipe DM18 kit includes both hose joints, both sealing washers, and both blanking caps – everything needed to connect or cap the cabin heating circuit on the MC13 engine. No additional hardware is required for a complete installation.
The part hose joints are machined from dezincification resistant brass, ensuring they do not corrode or seize even after years of exposure to hot coolant. This Cab heating connection pipe DM18 joint design provides a lasting, leak proof seal.
The composite sealing washers in this Cab heating connection pipe DM18 kit are made with FPM1 rubber, which resists heat, coolant, and aging. These Cab heating connection pipe DM18 washers maintain their sealing force over the life of the vehicle.
The supplied blanking caps allow The part ports to be sealed when the heater is not installed. This feature of The part helps maintain coolant pressure and prevent contamination of the heating circuit.
The part connects the engine coolant system to the cab heater core. The supply hose joint is installed on the engine block outlet (typically on the distribution housing), and the return hose joint is installed on the water pump inlet. Hot coolant (approx. 85 95°C) flows from the engine block through the supply hose joint,
through a rubber hose to the heater core, and returns through the return hose joint back to the water pump. The composite sealing washers ensure that coolant does not leak at the threaded connections. The blanking caps are used when the heater is not fitted, sealing the ports to prevent coolant loss. The part dimensions (DN18) are matched to the 18mm ID hoses commonly used in the MC13 heating circuit. Properly sealing The part ensures that the cab heater provides consistent heat, improving driver comfort and defrosting performance.
Before installing The part, ensure the engine is cool and the cooling system is depressurized. Remove the existing hose joints and blanking caps. Clean the threaded ports on the engine block and distribution housing. Install a new composite sealing washer onto each hose joint. Thread the supply hose joint into the outlet port and the return hose joint into the inlet port.
Torque both Cab heating connection pipe DM18 joints to 25 Nm using a wrench. Connect the rubber heater hoses to the barbed ends of the joints, securing them with worm drive clamps (not included). If the heater is not being connected, install the blanking caps into the ports instead of the hose joints, using the same composite washers. Refill the cooling system and start the engine, checking for leaks around The part joints. Top up coolant if necessary. The part installation is now complete.
If coolant leaks from the hose joint, the composite sealing washer may be damaged or the joint may be loose. Retorque The part joint to 25 Nm; if the leak persists, replace the washer. A cracked hose joint can occur if overtightened;
inspect the brass fitting for cracks. If the blanking cap leaks, ensure it is fully seated and the sealing surface is clean. If the heater does not produce heat, The part hoses may be kinked or blocked; inspect the routing. Air trapped in the heating circuit can also reduce heat; bleed the system using the bleed screw on the thermostat housing. If the hose joint threads are stripped, a thread repair insert may be needed.
The part components have no fixed replacement interval, but they should be inspected at every coolant change (every 80,000 km). Check the hose joints for signs of corrosion or thread damage. Inspect the composite sealing washers for cracking or flattening; replace them if any deformation is visible. The blanking caps should be checked for cracks if they are in use. When replacing coolant, always use new sealing washers to ensure a leak free Cab heating connection pipe DM18 connection. If the hoses are replaced, inspect the barbed ends of The part joints for sharp edges that could damage the hose.
This Cab heating connection pipe DM18 kit is specifically designed for the SINOTRUK MC13 engine used in HOWO MAX 4X2 tractors, SITRAK C7H, and HOWO T7H trucks. It fits all production years from 2018 onward. The part is also compatible with the MC11 engine, as the heating circuit ports are identical. This kit is not compatible with older WD615 or D10 engine series, which use different thread sizes and port locations. Always verify your engine serial number before ordering this Cab heating connection pipe DM18 kit.
Aftermarket hose joints may be made from inferior brass or steel that corrodes and leaks, causing coolant loss and heater failure. Generic sealing washers may be made from ordinary rubber that hardens and leaks, allowing air into the heating circuit. Blanking caps that do not seal properly can result in coolant seeping into the engine bay,
leaving stains and potential slippery spots. Genuine HOWO Cab heating connection pipe DM18 components are manufactured to SINOTRUK’s exact specifications, using certified brass, FPM rubber, and robust plastic caps. The small additional cost of a genuine Cab heating connection pipe DM18 is insignificant compared to the cost of a coolant leak that could lead to engine overheating or a heater that fails to provide heat in winter conditions.
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