Mercedes Coupes/Sedans/Wagons 1974-1984 Repair Guide

Camshaft

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REMOVAL & INSTALLATION 4 and 5-Cylinder Engines



See Figures 1 through 9

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Fig. Fig. 1: When removing the camshaft, first drain the coolant



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Fig. Fig. 2: Loosen the thermostat housing hose clamp ...



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Fig. Fig. 3: ... then disconnect the hose from the housing



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Fig. Fig. 4: Matchmark the relationship of the timing chain to the camshaft sprocket



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Fig. Fig. 5: Remove the timing chain guide retaining bolt ...



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Fig. Fig. 6: ... then remove the timing chain guide



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Fig. Fig. 7: Remove the camshaft gear retaining bolt ...



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Fig. Fig. 8: ... then remove the gear from the camshaft while still keeping tension on the timing chain



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Fig. Fig. 9: Keep tension on the timing chain and secure it with a wire, so it does not slip down into the chain case

EXCEPT 190D AND 190E MODELS

When the camshaft is replaced, be sure the rocker arms are also replaced.

  1. Remove the valve cover.
  2.  
  3. Remove the chain tensioner.
  4.  
  5. Remove the rocker arms.
  6.  
  7. Set the crankshaft at TDC for No. 1 cylinder and be sure that the camshaft timing marks are aligned.
  8.  
  9. Hold the camshaft and loosen the cam gear bolt. Remove the cam gear and wire it securely so that the chain does not loose tension nor slip down into the chain case.
  10.  
  11. Remove the camshaft.
  12.  
  13. Installation is the reverse of removal. Be sure to check that the valve timing marks align when No. 1 cylinder is at TDC. Check the valve clearance.
  14.  

190D AND 190E MODELS

On the 190E it is always a good idea to replace the rocker arms and shafts whenever the camshaft is replaced.

  1. Remove the valve cover.
  2.  
  3. Remove the chain tensioner.
  4.  
  5. On the 190E, remove the rocker arms and shafts.
  6.  
  7. Set the crankshaft at TDC for the No. 1 piston and make sure that the timing marks on the camshaft are in alignment.
  8.  
  9. Using a 24mm open-end wrench, hold the rear of the camshaft (flats are provided) and then loosen and remove the camshaft retaining bolt. Carefully slide the gear and chain off the shaft and wire them securely so they won't slip down into the case.
  10.  

Be careful not to lose the Woodruff key while removing the gear on the 190E.

  1. The camshaft is secured on the cylinder head by means of the bearing caps. Remove them and keep them in their proper order. Each cap is marked by a number punched into its side; this number must match the number cast into the cylinder head.
  2.  

When removing the bearing caps on the 190D, always loosen the center two first and then move on to the outer ones.

  1. Remove the camshaft.
  2.  
  3. Installation is in the reverse order of removal. Always make sure that the No. 1 cylinder is at TDC and all timing marks are aligned. Tighten the bearing caps to 15 ft. lbs. (21 Nm) on the 190E and 18 ft. lbs. (25 Nm) on the 190D. The camshaft gear retaining bolt should be tightened to 58 ft. lbs. (80 Nm) on the 190E and 33 ft. lbs. (45 Nm) on the 190D.
  4.  

Be certain not to forget the Woodruff key on the 190E.

6-Cylinder Engines See Figure 10

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Fig. Fig. 10: When removing the camshaft, unfasten the bolts in the sequence illustrated6-cylinder engines

With the engine installed in the car, the camshafts can only be removed together with the camshaft housing. If a new camshaft is installed, be sure to use new rocker arms.

  1. Remove the refrigerant compressor but do not disconnect the refrigerant lines.
  2.  
  3. Remove the battery.
  4.  
  5. Remove the vacuum pump from the right-hand cylinder head.
  6.  
  7. Drain the coolant and remove the water hoses.
  8.  


CAUTION
When draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.

  1. Remove the rocker arm cover.
  2.  
  3. Remove the cover from the front of the camshaft housing.
  4.  
  5. Remove the rocker arm springs.
  6.  
  7. Remove the rocker arms.
  8.  
  9. Crank the engine around in the normal direction of rotation (using the crankshaft bolt) until No. 1 piston is at TDC, the pointer aligns with the TDC mark on the crankshaft pulley and the camshaft timing marks are aligned.
  10.  
  11. Hold the camshaft(s) and loosen the camshaft bolts.
  12.  

Wire the camshaft gears up so that tension applied to the chain. The chain must not be allowed to slip off the camshaft or crankshaft gears.

  1. Remove the chain tensioner.
  2.  
  3. Remove the slide rail from the camshaft housing. You'll need a small puller for this.
  4.  
  5. Loosen the cover at the right-hand rear side of the camshaft housing and push the right-hand camshaft toward the rear. Remove the camshaft gear.
  6.  
  7. Loosen the camshaft housing retaining bolts. Do not loosen the 5 lower cylinder head bolts or the 2 M8 bolts.
  8.  
  9. Remove the camshaft housing with the camshafts.
  10.  
  11. Remove the rear covers from the camshaft housing.
  12.  
  13. Hold the left-hand camshaft and loosen the attaching bolt.
  14.  
  15. Push the camshaft rearward and remove the camshaft gear. Remove the spacer from the intake camshaft.
  16.  
  17. Remove both camshafts from the housing.
  18.  

To install:
  1. Oil the bearings and install the intake camshaft (left-hand) with cam gear and spacer. Use retaining bolt and washer (not springs).
  2.  
  3. Install the exhaust (right-hand) camshaft. Do not install the gear until the housing is installed.
  4.  
  5. Install the rear camshaft covers. Do not tighten the one on the right-hand side.
  6.  
  7. Install the camshaft housing.
  8.  
  9. Lubricate the bolts and tighten them in 3 stages:
  10.  



Starting with Bolt #2, tighten to 30 ft. lbs.
 
Starting with Bolt #2, tighten to 44 ft. lbs.
 
Starting with Bolt #1, tighten to 67 ft. lbs. First, slightly loosen the 5 lower cylinder head bolts.
 

  1. When you are finished torquing the camshaft housing bolts, torque the cylinder head bolts. When all bolts have finally been tightened, the camshafts should rotate easily and freely.
  2.  
  3. Install the righthand camshaft gear. Be sure the cam timing is accurate and the engine is set at TDC on No. 1 cylinder.
  4.  

Some engines have a scale for BDC as well as one for TDC. The TDC mark is next to the pin in the balancer.

  1. Install the timing chain rail.
  2.  
  3. Install the rockers and tension springs. Adjust the valves.
  4.  
  5. Crank the engine by hand and check the valve timing.
  6.  
  7. Tighten the camshaft gear bolts to 59 ft. lbs.
  8.  
  9. Install the chain tensioner.
  10.  
  11. Install the camshaft rear housing covers (if not already done) and the vacuum pump.
  12.  
  13. Install the rocker covers.
  14.  

V8 Engines See Figure 11

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Fig. Fig. 11: Install the compensating washer so that the keyway below the notch slides over the Woodruff key

Experience shows that the right-hand camshaft is always the first one to require replacement. When the V8 camshaft is removed, keep the pedestals with the camshaft. In particular, make sure that the 2 left-hand rear cam pedestals are not swapped. The result will be no oil pressure. Always replace the oil gallery pipe with the camshaft.

  1. Remove the valve cover.
  2.  
  3. Remove the tensioning springs and rocker arms.
  4.  
  5. Using a wrench on the crankshaft pulley, crank the engine around until No. 1 piston is at TDC on compression. Using some stiff wire, hang the camshaft gear so that the chain will not slip off the gears.
  6.  
  7. Remove the camshaft gear.
  8.  
  9. Unbolt the camshaft, camshaft bearing pedestals and the oil pipe. Note the angle of the bolts holding the cam bearing pedestals to the engine. The inner row of bolts are the only bolts that do not hold the head to the block.
  10.  

To install:
  1. Install the bearing pedestals and camshaft. On the left-hand camshaft, the outer bolt on the rear bearing must be inserted prior to installing the bearings or it will not clear the power brake unit. Tighten the bolts from the inside out. When finished tightening, the camshaft should rotate freely.
  2.  
  3. Check the oil pipes for obstructions and replace if necessary.
  4.  
  5. When installing the oil pipes, also check the 3 inner connecting pipes.
  6.  
  7. Install the compensating washer so that the keyway below the notch slides over the Woodruff key of the camshaft.
  8.  
  9. Install the rocker arms and tensioning springs.
  10.  
  11. Adjust the valve clearance and check the valve timing. See Valve Timing for illustrations.
  12.  

 
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