Originally Posted by Astra La Vista!
This is a detailed account of how to change out the timing belt on our Saturn Astras. Most of this info can be found in the Haynes manual that covers the European version of our cars. I've included torque values, tools needed, part numbers, and copious amounts of pictures. This procedure should be similar to the Z18XER engines found in the Chevrolet Cruze LS and Sonic.
Special tools needed:
E10, E16, E20 (female) Torx sockets
T20, T27, T55 (male) Torx sockets
6mm Allen key or socket
12-point 19mm (hex) socket - standard 6-point WILL NOT WORK!
Timing Belt - Gates T338 or GM 93180815 (OEM belt will be considerably more expensive)
Crank Pulley Bolt - since this is an actual "torque-to-yield" bolt, I chose to spend the $5 on an OEM replacement (GM# 24447224) - BOLT WAS BACK-ORDERED ONE WEEK SO YOU WILL HAVE TO PLAN THIS JOB WELL IN ADVANCE!
Serpentine Belt (with A/C) - Gates K050609 (I didn't bother sourcing an OEM belt, nor did I bother checking for the part number for a non-A/C engine)
Serpentine Belt Tensioner Bolt - possibly also "torque-to-yield" (text in Haynes manual not conclusive), but I chose to reuse and use red Loctite instead
Middle Timing Belt Cover - will be brittle during removal and tabs may break (cover is still held in place by other means)
First, park the car on level ground -- ideally a CLEAN concrete slab like a carport or garage floor. Sweep the area before hand, to make it easier to find dropped screws, etc. Loosen off the five lugbolts on the right front wheel, raise up the corner of the car with a hydraulic floor jack, and support it with a jackstand (you will need the jack elsewhere later on). Remove the wheel and set it aside.
You will see a formed plastic splash guard ahead of the wheel well arch liner. It is held in place with two plastic pushpins and four T20 Torx screws. The pushpins are of the two-piece design with the center core expanding the outer part. You have to push the core inward to allow the outer part to contract so that you can remove it, and you may push it all the way through and out the other side (where it will probably land on the inside of the splash guard or onto the ground). You will almost certainly knock loose a bunch of sand/dirt/gravel so a quick sweep of the broom afterwards is probably a good idea before continuing. I find using something like an old egg carton perfect for keeping various small parts like screws, etc. separate from each other.
Remove the small silver T27 Torx screw securing the rear mount for the air cleaner assembly, loosen off one of the band clamps at the MAF sensor, and remove the entire assembly from the car. This might be a good time to open it up and examine the air filter.
The serpentine belt tensioner on our Astras features a black E16 Torx bolt securing it to the engine, as well as a large silver "12-point bolt" above it and a lock pin hole below. You will need a 12-point 19mm hex socket or box end wrench here to turn this bolt to relieve the tension, and a small drill bit or Allen key to insert into the lock pin hole to hold it there.
*** A 6-POINT SOCKET is USELESS HERE -- IT MUST BE A 12-POINT! ***
Rotate the tensioner counter-clockwise as far as you can and then slip in your drill bit or Allen key to lock it in place. DRAW OUT THE BELT ROUTING TO REMIND YOU HOW TO REINSTALL IT AFTERWARDS. Remove the serpentine belt. You will need to remove the serpentine belt tensioner later on, so it is advisable to release the tension now so that you aren't handling a potential explosive device later on.
Remove the two E10 Torx screws holding the upper timing belt cover in place and set it aside.
Using an E20 Torx socket, rotate the crank pulley clockwise to position the engine on TDC. You need to line up the timing marks on the crank pulley and cam sprockets as shown. The marks on the crank sprockets should be lined up with each other, almost forming a line between the centerlines of the large center camshaft bolts -- I say "almost" because they didn't form a perfect line on my own car, nor do they line up perfectly in the picture in my Haynes (page 2C-5). BECAUSE OF THIS, I WOULD STRONGLY ADVISE YOU TO TAKE A FEW PICTURES OF ALL THREE TIMING MARKS AS A BACK-UP. Ideally, you want to put everything back together exactly how it came apart.
The next step involves removing the E20 crank pulley bolt so that you can remove the pulley. This can be done in one of two ways:
1) Use an assistant to stand on the brake pedal while the transmission is in gear to prevent the front wheels from turning as you apply torque, or
2) Insert a piece of metal like an Allen key or drill bit into an access slot near the lower front engine mount to jam the flywheel ring gear (see pics).
Remove the E20 crank pulley bolt and then simply remove the crank pulley (it will just fall off).
Remove the four E10 Torx screws holding the lower timing belt cover in place and set it aside. The fourth screw is located just above the serpentine belt tensioner and is visible from above. Behind it you will see additional timing marks on the lower gear and the oil pump housing.
Remove the single E16 Torx bolt holding the serpentine belt tensioner to the engine and set it aside. I HAVE CONFLICTING INFORMATION ON WHETHER OR NOT THIS IS A "TORQUE-TO-YIELD" BOLT. THE TORQUE SPECS IN MY HAYNES SAYS YES, BUT THE TEXT IN THE REMOVAL SECTION DOESN'T MENTION HAVING TO REPLACE IT WITH A NEW ONE AFTERWARDS (like it does with the crank pulley bolt). PLUS, MINE WAS HELD IN PLACE WITH FACTORY LOCTITE. I CHOSE TO REUSE THIS BOLT AFTER CLEANING UP THE THREADS AND APPLYING FRESH RED LOCKTITE AND TORQUING TO SPECS.
The right side engine mount (silver) is bolted to the body using three short E16 Torx bolts, and to a bracket (black) that is then bolted to the engine using three long E16 Torx bolts. YOU CAN LEAVE THE MOUNT AND BRACKET JOINED DURING REMOVAL. Loosen off all six bolts and then place your floor jack underneath the cast aluminum "oil pan" of the engine (my jack is padded so you might want to place a piece of soft wood in between). Gently raise the jack until you start to see the engine mount move upwards away from the body. With the mount no longer supporting the weight of the engine, remove the six bolts and set the mount assembly aside.
The middle timing belt cover is held in place by a single plastic tab at each end. THE PLASTIC TABS WILL BE VERY BRITTLE DUE TO BEING EXPOSED TO YEARS OF ENGINE HEAT AND THEY MIGHT BREAK IF YOU AREN'T CAREFUL (which is what happened to me). THE COVER CAN'T COME COMPLETELY LOOSE DURING NORMAL OPERATION BECAUSE IT IS SANDWICHED BETWEEN THE BLACK ENGINE MOUNT BRACKET AND THE ENGINE ITSELF, AND IT IS FURTHER HELD IN PLACE BY THE UPPER TIMING BELT COVER. THE SOLUTION IS TO EITHER SOURCE OUT A REPLACEMENT COVER BEFORE STARTING OR USE A DAB OF SILICONE BETWEEN THE BRACKET AND THE COVER TO KEEP IT FROM POSSIBLY VIBRATING WHEN REINSTALLED.
With all three timing belt covers removed, you will now have full access to the timing belt. The timing belt tensioner is located on your left (when viewed from the side of the engine bay) while the timing belt idler pulley is located on the right. Below the Torx bolt on the timing belt tensioner is a hex-shaped hole. Using a 6mm Allen key, rotate the tensioner clockwise and slip off the belt. MY HAYNES WASN'T CRYSTAL CLEAR AT THIS POINT, AND DIDN'T HAVE ANY PICTURES OF THIS CRUCIAL STEP! WTF!?! There is supposed to be a slot "on the inner edge of the tensioner body" where you can insert a small drill bit to keep the tensioner locked in place, but without pictures it was difficult to understand exactly what the author meant. The tension isn't that powerful and I was able to manage to remove the old belt without locking it in place.
Install the new timing belt, making sure that the camshafts don't move. If they do, simply reposition the sprockets to align the timing marks (you'll need a T55 Torx socket for this). An extra pair of hands might help here to keep the torque off of the tensioner while you reinstall the new timing belt, but I managed by myself. Release the torque from the tensioner and temporarily reinstall the crank pulley and bolt. IF YOU USED A PIECE OF METAL TO LOCK THE FLYWHEEL RING GEAR, REMOVE IT NOW! Rotate the crankshaft 720 degrees and recheck all of the timing marks -- REFERRING TO THOSE PICTURES YOU TOOK -- and start over if something is amiss.
Once you are confident that the timing marks all line up, lock the flywheel in place again (or have your assistant stand on the brakes) and remove the crank pulley.
Reassembly is basically the reverse of the above:
1) middle timing cover
2) engine mount (26 lb-ft for body bolts, 41 lb-ft for engine bolts)
3) serpentine belt tensioner (torque to 37 lb-ft)
4) lower timing cover
At this point, carefully reinstall the crank pulley -- ENSURING THAT THE PULLEY IS CENTERED ON THE END OF THE CRANK while you hand-tighten the new bolt & washer with your other hand. With the flywheel still locked (or your assistant still standing on the brakes), torque the pulley bolt to 70 lb-ft. Next, mark the position of the head of the bolt in relation to the washer, and then further tighten the pulley bolt 45 degrees. THIS SEEMS SOMEWHAT INACCURATE, WHICH IS WHY I BELIEVE USING A NEW TORQUE-TO-YIELD BOLT IS MANDATORY HERE. Unlock the flywheel afterwards.
Continue with the reassembly as follows:
5) upper timing cover
6) serpentine belt (you will need to lock the tensioner in place again)
7) air cleaner assembly
8) splash shield
9) wheel (81 lb-ft)