REMOVAL & INSTALLATION
- Drain the cooling system and crankcase. Remove the oil pan and radiator.
- Remove the cylinder front cover and water pump, drive belt, and camshaft timing gear.
- Use the clutch aligner T71P-P-7137-H or equivalent and remove the crankshaft sprocket.
- Align the keyway in the gear with the key, then slide the gear onto the shaft, making sure that it seats tight against the spacer.
Feed the timing chain around the crankshaft sprocket and then around the camshaft sprocket. Install the camshaft sprocket together with timing chain as an assembly. Align all necessary timing marks.
- Check the camshaft end play. Refer to checking camshaft. If not within specifications, replace the thrust plate.
- Align the keyway in the crankshaft gear with key in the crankshaft, and align the timing marks. Install the gear, using a crankshaft sprocket replacer tool.
- Install the cylinder front cover following the procedures in this section. Install the oil pan and radiator.
- Fill and bleed the cooling system and crankcase.
- Start the engine and adjust the ignition timing.
- Operate the engine at fast idle and check all hose connections and gaskets for leaks.
See Figures 1 and 2
- Disconnect the negative battery cable.
- Drain the cooling system and crankcase.
- Remove the timing cover.
- Rotate crankshaft until No. 1 piston is at TDC and timing marks are aligned in the correct position.
- Remove the camshaft sprocket retaining bolt and washer. Check timing chain deflection for excessive wear.
- Slide sprockets and timing chain forward and remove as assembly.
- Clean timing cover and oil pan sealing surfaces. Clean and inspect all parts. The camshaft retaining bolt has a drilled oil passage for timing chain assembly lubrication. Clean oil passage with solvent. Do not replace with standard bolt.
- Slide sprockets and timing chain on as assembly with timing marks in the correct location. Install camshaft retaining bolt and washer. Torque bolt to 46 ft. lbs. Lubricate the timing chain assembly.
- Install timing cover assembly. Install retaining bolts with pipe sealant and tighten as outlined.
- Refill and bleed cooling system. Connect the negative battery cable. Start engine check for coolant, oil and exhaust leaks.
See Figures 3 and 4
Review the complete service procedure before starting this repair. Refer to the necessary service procedures in this section.
- Disconnect the negative battery cable.
- Drain the cooling system.
- Remove the front cover.
- Remove the radiator.
- Rotate the engine by hand until the No.1 cylinder is at TDC compression, and the timing marks are aligned.
- Remove the lower tensioner bolt and install a holding clip in the bolt hole and the slot on the rubbing block.
Unbolt and remove the tensioner.
- Remove the camshaft sprocket bolt and sprocket retaining key.
- Remove the camshaft and crankshaft sprockets with the timing chain.
- If necessary, remove the chain guide.
- Install the timing chain guide. Make sure the pin of the guide is in the hole in the block. Tighten the bolts to 84-96 inch lbs.
- Align the timing marks on the crankshaft and camshaft sprockets and install the sprockets and chain.
- Install the camshaft sprocket bolt and sprocket retaining key. Make sure that the timing marks are still aligned.
- Install the tensioner with the clip in place to keep it retracted.
- Install the crankshaft key. Make sure the timing marks are still aligned.
- Make sure the tensioner side of the chain is held inward and the other side is straight and tight.
- Install the camshaft sprocket bolt and tighten it to 50 ft. lbs.
- Remove the tensioner clip.
- Check camshaft end-play.
- Install the front cover.
- Install the radiator.
- Fill the cooling system.
- Fill the crankcase to the proper level. Connect the negative battery cable. Start engine check for leaks and roadtest the vehicle for proper operation.
See Figures 20 through 25
On the 4.0L SOHC engine, there are four chains which are used to time the camshafts and balance the engine. There is a jackshaft mounted in the middle of the engine block. The two camshafts are connected to the jackshaft by two chains. The jackshaft is connected to the crankshaft by a third chain. Also, a balance shaft assembly is chain driven off of the crankshaft and timed to the rotation of the engine.
In order to remove either of the camshaft timing or balance shaft chains, the jack shaft chain and sprockets must first be removed. Once the jackshaft chain is removed, the left-hand camshaft and the balance shaft chain can be serviced. In order to remove the right-hand camshaft chain, the jackshaft must be removed. Additionally, in order to service either camshaft chain assembly, the cylinder heads must be removed.
According to the manufacturer, the engine must be removed in order to service the timing chain and sprocket assemblies.
- Remove the engine from the vehicle.
- Remove the oil pan and ladder frame.
For ladder frame removal procedures, refer to the oil pump removal and installation procedure in this section.
- Remove the front cover attaching bolts and remove the cover.
- Remove the cylinder heads
- Install a pin in the jackshaft tensioner to hold it in the locked position.
- Loosen and remove the jackshaft sprocket bolt.
- Remove the jackshaft sprocket and chain assembly.
- Remove the left-hand front cassette retaining bolt and remove the cassette (chain and tensioner assembly).
- Position the engine to gain access to the rear of the engine. Ensure that the flywheel is removed.
- Remove the rear jackshaft plug from the back of the engine block.
- Remove the right-hand rear cassette retaining bolt and spacer.
- Loosen and remove the rear jackshaft sprocket bolt, then remove the cassette (chain and tensioner assembly).
- If the balance shaft chain is to be serviced, do it before installing the timing chains.
- Thoroughly clean all gasket mating surfaces. Use new gaskets and coat them with a sealer/adhesive.
- Install the right-hand rear cassette and the sprocket-to-jackshaft bolt.
- Install the rear cassette retaining bolt.
- Install the rear jackshaft plug.
- Install the front cassette and its retaining bolt.
- Position jackshaft sprocket and chain on the engine and remove the tensioner pin.
Install the jackshaft sprocket bolt and tighten in two stages.
- Stage 1: 32-35 ft. lbs. (43-47 Nm)
- Stage 2: Turn an additional 65-75
- Install the cylinder heads. Time the chains as outlined in the cylinder head procedure.
- Install the front cover and tighten all of the bolts.
- Install the ladder frame and oil pan.
- Install the engine into the vehicle.
- Run the engine and check for leaks.
See Figure 26
- Remove the engine front cover.
- Rotate the engine until the No. 1 piston is at TDC. Align the timing marks on the camshaft sprocket to the crankshaft sprocket.
- Remove the camshaft sprocket retaining bolt.
- Slide the crankshaft and camshaft sprockets and chain forward until all three components are removed.
- Position the crank and camshaft sprockets and chain assembly to the engine.
- Ensure that the timing marks on the two sprockets are aligned.
- Install the camshaft sprocket bolt and washer. Tighten to 40-45 ft. lbs. (54-61 Nm).
- Install the front cover.
- Start the engine and check for leaks.
TIMING CHAIN DEFLECTION
- Remove the timing chain tensioner.
- Rotate the crankshaft counterclockwise (as viewed from the front of the engine) to take up the slack on the left hand side of the chain.
- Mark a reference point on a block approximately at mid-point of the chain. Measure from this point to the chain.
- Rotate the crankshaft in the opposite direction to take up the slack on the right hand side of the chain. Force the left hand side of the chain out with your fingers and measure the distance between the reference point and the chain. The deflection is the difference between the two measurements.
- If the deflection measurement exceeds specification, replace the timing chain and sprockets.
- If the wear on the tensioner face exceeds 1.5mm, replace the tensioner.
- When installing the crankshaft sprocket, fill the keyway chamfer cavity with EOAZ-19554-AA Threadlock and Sealer or equivalent, flush with the front face of the sprocket.