Genuine BMW 335i Timing Chain

BMW 335i Timing Chain Parts Questions & Experts Answers

• Timing Chain
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  Q: What are the steps involved in disassembling, removing, and reassembling the camshafts, camshaft adjustment units and timing chain on BMW 335i?

  A:

  Specific equipments and new parts are needed in order to perform this repair procedure, and it is necessary to read the whole procedure before starting to repair. Lack of special tools necessary when performing disassembly, removal or assembly of camshafts or camshaft adjustment units exposes the parts to prospect of breakage or, at the very least, the valves may bend due to contact with the crowns of pistons. During the procedure unless otherwise stated the crankshaft and all camshafts are secured against rotation by applying the BMW special tools. The best here is to remove the cylinder head cover and all spark plugs, the crankshaft seal if at the front and the drive belt tensioner. Change the position of the crankshaft and position cylinder 1 at the TDC firing position with the aid of the vibration damper bolt so that the intake camshaft lobe is up. By so doing, when cylinder 1 is at TDC, one will observe that the exhaust camshaft cams point upwards. To check camshaft timing is correct, there is an orientation by part numbers or code on both intakes and exhausts, in addition the camshafts should face upwards. Screw on special tools 11 8 535 to 11 8 531, using an M10 washer with a thickness of 6 mm between the crankcase and the short screw of the special tool 11 8 535. Place special tool 11 8 537 on the sealing cap and screw in special tool 11 8 534 to expel the vacuum pump sealing cap which has to be expelled diagonally. In case the transmission is removed, tighten the flywheel with tool number 11 9 260; if the manual transmission is used, screw tool number 11 8 180 on the transmission using the bolts marked 'A' tighten the bolt labeled 'B' For an automatic transmission, fasten the flywheel by using the tool 11 8 660 through the transmission bell housing slit. Insert your finger through the vacuum pump sealing cap opening and compress the timing chain with the chain tensioner to ease tension on the oil pump chain Finally set a suitable lock pin to the chain tensioner. Take out the center bolt and it is to be pointed out that the breakaway torque is 600 Nm (440 ft-lb) and a 3/4-inch drive socket/breaker has to be used in order to loosen it. The Timing Chain Tensioner is then to be removed; the vibration absorber screws are then to be screwed in; and the hub on the crankshaft is pulled forward to be removed. Remove the connecter plugs found at the upper left of the housing and the lower right end of it and also , take out the chain guide mounting bolt at the upper left. Pop in special tool 11 4 280 and start with the center bolts on the front of the intake and exhaust camshaft adjusters and loosen and remove. Take out the intake and exhaust camshaft adjusters from the timing chain and place them aside and detach the chain tensioning rail mounting bolt at the at low right of the timing chain sprocket cover. Four bolts securing the timing chain assembly are on the front side of the cylinder head; dismantle by lifting the timing chain along with the timing chain assembly and crankshaft sprocket from the timing chain housing. Remove the timing chain from the ID and rail and crankshaft sprocket and fit a new timing chain. Align the crankshaft sprocket with the chain positioning the collar facing the engine, this is to ensure that the sprocket is assembled in the right way so that an engine is not ruined. Stretch the timing chain until the sprocket meshes with the chain guide and then fix the timing chain and the chain assembly into the housing with an appropriate tension of the chain. Bolt on the timing chain assembly and its rail together with its guide bolts and tighten in the correct manner. After engaging the crankshaft, fix a new bolt with the place for the crankshaft hub; then torque from the centred bolt using an angle protractor. Fit a new crankshaft seal; refit the camshaft adjustment units with the note that exhaust and intake units are not identical. Introduce the camshaft timing and tighten the adjustment unit mounting bolts; thereafter, fit the timing chain tensioner. Take out the locking tools and rotate the engine two full revolutions, adjust the camshaft timed if it is required. Finally the new sealing cap for the vacuum pump is fitted until it lies flush with the upper part of the crankcase, and the rest of the procedure can be said to be a reversal of the process of removal.