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Autopapyrus · Nissan X-Trail 2.5 QR25DE (2004)
https://autopapyrus.com/guides/nissan/x-trail/cylinder-head-replacement/
Compiled automatically from service literature and owner experience. Specs are for the typical configuration — check them against your exact car before you start.

Nissan X-Trail 2.5 QR25DE (2004): Cylinder Head Replacement

The QR25DE is an aluminum 4-cylinder engine with two camshafts and a timing chain drive. It needs no belt, but the chain must be removed carefully and re-timed using the marks. The head is replaced for cracks, warpage beyond tolerance after overheating, or burned seats or valves. The heads on this engine are not designed for heavy machining, so if warpage exceeds the limit, it is better to replace the head than to resurface it.

Difficulty: Hard Time: 1-2 days (6-10 hours of work, not including inspection and machine shop work) Steps: 17 Tools: socket and ratchet set, torque wrench (up to 100-150 N·m (74-111 lb-ft)), angle gauge for angle tightening, TORX/E-type sockets for the cylinder head bolts, syringe or vacuum pump for removing oil from the wells, straightedge and feeler gauges for checking flatness, camshaft holding tool or lock, sealant, marker and containers for fasteners.

Parts

2
  • 🔩 cylinder head assembly or bare head, top-end gasket set (MLS head gasket, valve cover gasket, intake and exhaust manifold gaskets), new cylinder head bolts (single-use, angle-tightened), Nissan L250 coolant or equivalent (about 8 L (8.5 qt)), engine oil and oil filter. Select the head gasket and bolt part numbers by VIN
  • 🔩 none are listed here, to avoid inventing them
There's a full repair manual for this car Every system, wiring diagrams and torque specs — not just this job. Haynes and 4 more. See manuals →

Step by step

17 steps
  1. Let the engine cool completely. Disconnect the negative battery terminal. Remove the engine undercover and drain the coolant from the radiator and engine block. Drain the engine oil.
  2. Remove the air duct and the air filter housing with the mass airflow sensor, the engine cover, the ignition coils and the spark plugs. Label the connectors and hoses, photograph their layout, and disconnect the connectors for the injectors, sensors and throttle.
  3. Remove the intake manifold together with the throttle body, after first disconnecting the fuel rail (relieve the fuel system pressure, pull the fuel pump fuse and let the engine run until the remaining fuel is used up). Cover the open ports with a clean rag. Detach the coolant and heater hoses from the manifold and head.
  4. Disconnect the exhaust manifold from the downpipe and remove it together with the heat shield. If the studs and nuts are seized, treat them with penetrating oil beforehand. Carefully unscrew or disconnect the oxygen sensors.
  5. Remove the valve cover. Check the condition of the oil in the wells, and look for carbon buildup and traces of coolant. Set cylinder No. 1 to TDC on the compression stroke using the marks on the pulleys and chain, and lock it in position.
  6. Remove the upper timing chain cover (if required on your version) and the chain tensioner. Mark the position of the chain relative to the sprockets with paint. Remove the camshaft sprockets together with the chain, and tie the chain up with wire so it cannot fall into the oil pan. The timing marks must line up exactly during reassembly.
  7. Remove the camshaft bearing caps, loosening them in the proper sequence (from the ends toward the center, in stages, so the shafts do not bend), and take out the camshafts. Lay out the caps and bearing shells in installation order. If the head is being replaced complete with camshafts, they can also be transferred to the new head.
  8. Loosen the cylinder head bolts in the reverse of the tightening sequence: from the ends toward the center, in several passes. The bolts are single-use, and reusing them is not recommended. Remove the head, prying carefully if needed at the points provided in the casting. Do not strike the mating surface.
  9. Clean the block surface of gasket residue with a plastic scraper, taking care not to scratch the aluminum. Cover the cylinders and oil passages with rags. Check the flatness of the block and of the new or old head with a straightedge and feeler gauge. The manufacturer's warpage limit is usually very small (on the order of hundredths of a millimeter), so if it is exceeded, replace the head. Blow out the bolt holes in the block and remove any oil and coolant from them. Otherwise hydrolock and incorrect tightening are possible.
  10. If you are installing a new or reconditioned head, check the valves, seats, lifters or hydraulic lash adjusters, and the condition of the cam lobe and journal surfaces. Lubricate the camshaft journals and lobes with engine oil or assembly lube.
  11. Install the new head gasket without sealant, in exactly the orientation shown by its markings (TOP or an up arrow, cylinder numbers). Set the head onto the dowel pins of the block.
  12. Lubricate the threads and the underside of the heads of the new bolts with a thin layer of engine oil, and tighten them in stages in a spiral pattern from the center outward. The sequence on this engine is: initial tightening at a high torque (about 90-100 N·m (66-74 lb-ft)), loosen completely to zero, then tighten at a lower torque (about 30-40 N·m (22-30 lb-ft)) and finish with an angle turn (usually about 90-100 degrees, done in two stages). Check the exact torque and angle values for your engine against the manufacturer's specifications, as they differ between revisions.
  13. Install the camshafts and tighten the bearing caps in stages in the correct sequence to the specified torque (low, usually 10-20 N·m (7-15 lb-ft)). Fit the chain onto the sprockets exactly on the marks, install the tensioner and remove the locking pin. Turn the crankshaft two full revolutions by hand and recheck that the marks line up. If the marks do not align, do not start the engine.
  14. Install the valve cover with a new gasket, and apply sealant to the corners and joints at the locations specified in the manual. Tighten the cover bolts evenly without overtightening (low torque, about 8-12 N·m (71-106 lb-in)).
  15. Install the exhaust manifold with a new gasket (tighten the nuts to about 35-45 N·m (26-33 lb-ft)), then the intake manifold with new gaskets (tightening approximately 15-25 N·m (11-18 lb-ft)). Reconnect all hoses, connectors, the fuel rail, sensors and the air duct. Install the spark plugs (about 20 N·m (15 lb-ft)) and the coils.
  16. Fill with new oil and install a new filter. Fill with coolant, warm up the engine with the coolant reservoir cap open, and bleed the air pockets (set the heater to maximum and periodically squeeze the upper radiator hose). Check the level after the engine cools.
  17. First start: let the engine idle for 5-10 minutes and check for oil and coolant leaks, exhaust and manifold sealing, and any fault codes in the control unit. Take a test drive, then after the engine cools top up the coolant and check the oil level. Retightening the head bolts is not required on this engine with single-use, angle-tightened bolts, unless the gasket manufacturer states otherwise.

Common mistakes and warnings

  • This is a difficult job. A mistake in installing the timing chain causes the valves to hit the pistons and leads to expensive repairs. If you have no experience with valve timing and torque tools, have a repair shop do the replacement. Before replacing the head, find out the cause of the failure (overheating, head gasket leak, ring wear), or the failure will happen again. Do not pour coolant onto the ground; dispose of it properly.