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Timing Belt Change -- Page 5
Replacing Cam Seals & Alternator
Replacing PCV Valve
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Replace Timing Belt and ReAssembly
Timing Belt Change -- Page 2
Timing Belt Change -- Page 3
Timing Belt Change -- Page 4
Changing the Spark Plugs
Timing Belt Change -- Page 1
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Mitsubishi 3.0 SOHC Engine

Replacing the Timing Belt and ReAssembly of Engine

At this point of the job, nearly all of the hard work is done. There remain only one or two more tricks to getting the timing belt installed correctly. Given that you have (presumably) taken the time to correctly position the # 1 piston to TDC, you are ready to go.

First, take the timing belt and align it over the front (left) cam sprocket, the crank sprocket and the tensioner. The tensioner spring will typically still be off at this stage. You want to make sure that the timing marks are lined up for these two.

Note that the timing mark on the L front cam sprocket is off about a half-notch clockwise. This is deliberate, allowing the cam sprocket to rotate backwards into position a half-notch as the belt takes up tension. This helps avoid the "off by one notch" problem. The timing belt teeth must line up EXACTLY with the marks, and can't be off by even one notch/tooth.

timing_belt_new_inplace.jpg

Here you will need the strap wrench to re-position the left (rear) cam sprocket, either 90 degrees clockwise or counter-clockwise. It should balance in place enough for the timing belt to be mounted. Again, rotate it just a half-notch clockwise past the mark. This way, the tension pulling both cam sprockets counter-clockwise will tighten the belt in correct position. Also check its position on the waterpump pulley.

cam_sprocket_strap_wrench.jpg

With the belt daintily mounted just so, and the tensioner spring loose, bring the belt around the tensioner and place some pressure to the right to keep the belt in place. Then, with herculean strength, use a needle-nose pliers to expand the spring and hook it around the WP mounting post in the notch.

Check the timing marks again.

timing_belt_old.jpg

At this point, a final check of the timing marks is made. Also, check that the distributor rotor is pointing at the mark you made on the distributor body.

One last check of the timing setup for the truly paranoid and compulsive. This is the "straw test". Ideally, remove the #1 plug and place a straw (attached to a large clamp so it cannot be lost) and lower it into the cylinder. If you are lined up correctly, the straw should immediately come into contact w/ the cylinder head, verifying the position of # 1 piston at TDC.

On this engine, the # 1 plug is very hard to get at, however. An alternative is to check this when you have the left rear timing cover removed, along with the alternator bracket (see below). Another is to use the #2 piston, and verify that it is approaching TDC, i.e. just below the cylinder top. Since this fires next, you should be good. Also, you can rotate the crankshaft 60 degrees clockwise to bring #2 to TDC and do the straw test on that cylinder.

alternator_bracket_mountings_no1plugwire_label.jpg

Make sure that the timing belt tensioner is torqued to specifications. Now rotate the crankshaft through one entire cycle to verify the position of everything, and to see that it does not slip. The spring on the tensioner should provide the correct tension for the belt. You will need to briefly remount the crank bolt for this.

crank_rotating_socket.jpg

If you have removed the cam sprockets and only tightened them a little, be sure to torque them (70 ft-lbs) before you move on.

The best way to do this is to fashion a tool out of a piece of straight iron and two short, squat bolts to fit into the holes off-center on the cam sprockets. This tool can be used to hold the sprocket while the main bolt is torqued -- see tool in photo. (Do not use this tool to hold the cam sprocket in place while torquing the crank bolt as shown in this photo -- you will cause the timing belt to slip).

cam_sprocket_tool.jpg

At this point, engine re-assembly is not difficult if you have been organized. First, replace the timing covers, taking care with which bolts go where. Just slightly tight only or you will break the plastic.

timing_cover_inplace.jpg

Next, remount the engine support bracket. Torque them per then manual. Remember to tighten the loose power steering pump bracket bolts under the engine. Then replace the engine mount and the idler pulley. Remove the supports from under the engine.

reassembly_final_coversandbracket.jpg

engine_mount_remounted.jpg

After that, you can remount the engine dampener on the crankshaft. I used a propane torch to warm it up so it slipped more easily over the crankshaft. After it cools, re-mount the main crank pulley and A/C accessory pulley.

At this point, you must torque the crank pulley. You can get it a little tight by removing the front (R) timing cover and holding the cam sprocket in place. This runs the risk of slipping the timing belt.

There is really only one way to do it right on an automatic transmission, and that is to use a air impact wrench. If you don't have one, you can pull the starter and wedge something against the flywheel .... not very elegant. (On the manual transmission, put the car in 5th and have someone stand on the brakes).

crank_pulley_torque.jpg

Finally, replace both accessory belts. Remember to tension adjust the A/C belt. Re-mount the distributor cap, and re-attach all of the wires to their appropriate plugs. Don't forget to tighten any plugs you have loosened in the process. Also remember to re-assemble any part of the cooling system (e.g. fill the radiator).

Do a final check. Make sure there is oil in the engine. Also verify that the cooling system is all tightened up. As a last step, re-attach the battery cables and then try a re-start. Check for oil leaks and listen to the engine through a few gentle revs. Re-mount the wheels, drop the jackstands and you are ready to go.

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