BMW 11127588249 Cylinder Head

To remove the N55 engine cylinder head, first remove the engine, as special tools and procedures are necessary for the removal and installation of camshaft adjustment units and for timing camshafts. It is important to read the entire procedure before beginning repairs. Disassembly, removal, and assembly of camshafts, camshaft adjustment units, or the cylinder head without BMW special tools can lead to damage or breakage, such as bent valves from contact with piston crowns or a camshaft snapping if bent by valve springs. If a cylinder head requires significant reconditioning work after removal, a remanufactured cylinder head is available from an authorized BMW dealer.

Insert BMW special tool 11 4 430 or equivalent sealing plugs into bore holes and remove coarse residues on sealing surfaces from the cylinder head and crankcase, taking care not to use metal-cutting tools to avoid damage. Use BMW special tool 11 4 472 or equivalent grindstone to remove fine residues, ensuring all blind holes are cleaned to eliminate coolant, water, or engine oil to prevent cracking or corrosion. Inspect the cylinder head for visible cracks or defects, and check for warpage by removing intake and exhaust camshafts, roller cam followers, valve lifters, and valves. Use a straight edge to assess the evenness of the sealing surface in both longitudinal and transverse directions, and have the cylinder head tested for coolant leaks and cracks. If warped but sound, machine a maximum of 0.3 mm (0.011 in) off the sealing surface, then reassemble or use a reconditioned BMW cylinder head, ensuring it is placed on its side to avoid valve damage. Replace the cylinder head gasket with a special one from an authorized BMW dealer if machined, as it is 0.3 mm (0.011 in) thicker than standard. Position the cylinder head on the engine block, fitting it to the aligning sleeves, and install new cylinder head bolts using the appropriate BMW special tools. Retrieve the timing chain from the housing, place it over the chain module, and reattach the module with new bolts, noting the differences between exhaust and intake camshaft adjustment units. Lock down the camshafts with the specified tools, install the chain tensioner, and set the camshaft timing. If reusing the chain tensioner, drain its oil chamber and compress it slowly. Ensure a new sealing O-ring is used during reassembly. The remainder of the installation follows the reverse order of removal, including removing locking tools, assembling the cylinder head cover with a new gasket, reattaching ground cables, reinstalling the engine, adding fresh engine oil, checking the oil level, and filling and bleeding the cooling system.

No sealing ring is fitted to the chain tensioner at the factory, so use a new sealing O-ring during reassembly.

It is important to read the entire procedure to ensure proper execution of the repair process and to avoid potential issues.

It is important to read the entire procedure to ensure that the disassembly, removal, and assembly of camshafts, camshaft adjustment units, or the cylinder head are done correctly, as improper handling can lead to damage or breakage.

Pretension the eccentric shaft and remove the stop screw between cylinders 1 and 2.

Use the special tool set to lock down the camshafts, then remove the intake and exhaust camshaft adjustment units by loosening and discarding the mounting bolts, removing the timing chain tensioner while catching any dripping oil, and disengaging the timing chain from the camshaft adjustment unit sprockets.

Remove coarse residues on sealing surfaces from the cylinder head and crankcase with a scraper, avoiding metal-cutting tools to prevent damage.