Saturday, July 21, 2012

How to replace Timing chain on 1985 Oldsmobile Cutlass?

The procedure to replace timing chain

The details and diagrams are as follows:---

See Figures 1, 2, 3, 4, 5, 6 and 7
V8 Chevrolet Built Engines
All Chevrolet V8 engines are equipped with a timing chain.
  1. Remove the crankcase front cover. This will allow access to the timing chain.
  2. Crank the engine until the marks punched on both sprockets are closest to one another and in line between the shaft centers.
  3. Take out the three bolts that hold the camshaft sprocket to the camshaft. This sprocket is a light press fit on the camshaft and will come off readily. It is located by a dowel. The chain comes off with the camshaft sprocket.
  4. A gear puller will be required to remove the crankshaft sprocket.
To install:
  1. Without disturbing the position of the engine, mount the new crank sprocket on the shaft, then mount the chain over the camshaft sprocket.
  2. Arrange the camshaft sprocket in such a way that the timing marks will line up between the shaft centers; and the camshaft locating dowel will enter the dowel hole in the cam sprocket.
  3. Place the cam sprocket, with the chain mounted over it, in position on the front of the camshaft and pull up with the three bolts that hold it to the camshaft.
  4. After the sprockets are in place, turn the engine two full revolutions to make certain that the timing marks are in correct alignment between the shaft centers.
  5. Install the crankcase front cover.
V8 Oldsmobile Built Engines
  1. Disconnect the negative battery cable. Remove the timing case cover and take off the camshaft gear.
The fuel pump operating cam is bolted to the front of the camshaft sprocket and the sprocket is located on the camshaft by means of a dowel.
  1. Align the timing marks on the sprockets.
  2. Remove the oil slinger, timing chain, and the camshaft sprocket. If the crankshaft sprocket is to be replaced, remove it also at this time. Remove the crankshaft key before using the puller. If the key can not be removed, align the puller so it does not overlap the end of the key, as the key-way is only machined part of the way into the crankshaft gear.

Oldsmobile timing chain
Fig. Fig. 1: Before removing the timing chain, make sure the valve timing marks are properly aligned

Click image to see an enlarged view
Fig. Fig. 2: Remove the camshaft sprocket attaching bolt and fuel eccentric

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Fig. Fig. 3: Remove the camshaft sprocket

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Fig. Fig. 4: Use a puller to loosen the crankshaft sprocket

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Fig. Fig. 5: Before completely removing the crankshaft sprocket, remove the crankshaft key
To install:
  1. Reinstall the crankshaft sprocket being careful to start it with the keyway in perfect alignment since it is rather difficult to correct for misalignment after the gear has been started on the shaft. Turn the timing mark on the crankshaft gear until it points directly toward the center of the camshaft. Mount the timing chain over the camshaft gear and start the camshaft gear up on to its shaft with the timing marks as close as possible to each other and in line between the shaft centers. Rotate the camshaft to align the shaft with the new gear.
  2. Install the fuel pump eccentric with the flat side toward the rear.
  3. Drive the key in with a hammer until it bottoms.
  4. Install the oil slinger.
263 Oldsmobile Built Diesel Engines
Any time the timing chain and gears are replaced on the diesel engine it will be necessary to re-time the engine. Refer to the paragraph on Diesel Engine Injection Timing.

Click image to see an enlarged view
Fig. Fig. 6: Engine front cover and timing chain assembly - 350 Oldsmobile diesel engines

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Fig. Fig. 7: Timing mark alignment - Oldsmobile built engines
  1. Remove the front cover. Remove the valve covers.
  2. Loosen all rocker arm pivot bolts evenly so that lash exists between the rocker arms and valves. It is not necessary to completely remove the rocker arms unless related service is being performed.
  3. Remove the crankshaft oil slinger and the camshaft sprocket bolt and washer.
  4. Remove the timing chain, camshaft and crankshaft sprockets. If the crankshaft sprocket is a tight fit on the crankshaft use an appropriate puller to remove it.
To install:
  1. If the camshaft sprocket-to-cam key comes out with the camshaft sprocket, remove the front camshaft bearing retainer and install the key into the injection pump drive gear. Install the bearing retainer.
  2. Install the key in the crankshaft, if removed.
  3. Install the camshaft sprocket, crankshaft sprocket and the timing chain together, align the timing marks on the camshaft and the crankshaft. Tighten the camshaft sprocket bolt to 64 ft. lbs. (86 Nm)
  4. Install the oil slinger and the remaining parts of the front cover assembly.
  5. After installing the front cover, bleed down the valve lifters as instructed in Diesel Engine, Rocker Arm Replacement, above.
  6. Remaining installation is the reverse of removal. Sealant is used in place of valve cover gaskets.

These details will help.

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