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Wednesday, November 9, 2011

How to Change the Timing Belt on a 2.0L, 4 Cylinder Mazda 626 1993 to 2002

Overhead cam (OHC) cover removed and motor mount bracket is still bolted on the block the timing belt and plastic timing upper half-cover is still on. Click to enlarge.
Overhead cam (OHC) cover removed and motor mount bracket is still bolted on the block the timing belt and plastic timing upper half-cover is still on. Click to enlarge.

This guide suggests how to change the timing belt which has neither come off nor skipped badly.

Steps

  1. 1
    Obtain a manual and confirm that it has torquing instructions for bolts. Compare the instructions in the book to this article and follow any recommendations about removal, installation/replacement, pictures and diagrams that may be helpful. The OEM (original equipment manufacturers) repair manuals do not explain in detail for the inexperienced and may advise use of unnecessary tools or ignore explanation of basic techniques as it is written for an audience of Mazda mechanics. The tools needed in this repair will be mentioned in each step.


  2. 2
    Work on level ground and block the wheels (so they won't roll) with bricks or wooden pieces about the size of a bricks. Put on the parking brake.
  3. 3
    The engine mount is off - and the engine is supported by a jack. note a white rubber "wine bottle-stopper" is the cam sprocket stop-block; notice the tensioner pulley with Allen (Hex) Wrench in its tool hole. Toward the right idler pulley retaining bolt passes directly through the "shiny aluminum" water pump behind and below the idler. Click to enlarge.
    The engine mount is off - and the engine is supported by a jack. note a white rubber "wine bottle-stopper" is the cam sprocket stop-block; notice the tensioner pulley with Allen (Hex) Wrench in its tool hole. Toward the right idler pulley retaining bolt passes directly through the "shiny aluminum" water pump behind and below the idler. Click to enlarge.
    Avoid engine damage from the timing belt breaking or slipping, or the tensioner pulley or idler pulley locking up (seizing) or the timing belt skipping one or more cogs on a sprocket causing valve timing problems and possibly breaking valves, pistons and/or the engine cylinder (block):
  4. 4
    Understand the numbering of the cylinders and label the spark plug cables and cylinders 1, 2, 3, 4 from left to right but the other end is not that easy and carefully pry and get the cables off their spark plugs.
  5. 5
    Check your manual for firing order which will be 1, 3, 4, 2 or such for 1993--1997 (verify this carefully) and 1, 4, 3, 2 or such for after 1998 for how they plug onto the coil pack or distributor on older models.[Storer, J, and Haynes, John H, (1999, 2001), Mazda 626 and MX6 Ford Probe Repair Manual, ISBN 1-56392-440-4]
  6. 6
    Drain all the coolant from the engine and keep it to use again or dispose of it legally; no matter how little.
  7. 7
    Remove the accessory belt(s) for the alternator, power steering, air conditioner, etc:
  8. 8
    Organizing screws, bolts & tools helps a lot.
    Organizing screws, bolts & tools helps a lot.
    Remove the bolts holding the power steering pump by unbolting the 3 bolts to release the power steering pump bracket from the engine (12mm and 14mm), but without opening or unsealing the power steering hoses or you will need to drain it and refill it when finished. This will help get some working space, where it is difficult to loosen and tighten the lock bolt on the power steering tensioner with a combination wrench (14mm) even by switching ends of the wrench. Do not pry belts off or on.
  9. 9
    Loosen the long bolt of alternator pivoting bracket on the alternator belt to allow the adjustable accessory to pivot as tension is released. Loosen the tensioner enough to remove the belt. The older models have two flat belts (not v-belts) and newer models probably have a single serpentine belt.
  10. 10
    If your newer model is equipped with a serpentine belt, follow those instructions in your manual and obey the diagram.

Removing spark plugs, harmonic pulley, valve cover

  1. 1
    Remove two short 10mm bolts holding the power steering hose where it crosses the valve cover and work the hose toward the left out of the way. One of the 10mm bolt that will be removed later was covered, but is now reachable by moving the power steering hose.
  2. 2
    Remove spark plugs - use a specialized spark plug socket with a rubber grommet inside which helps to lift plugs from the deep ports. If you do not have a spark plug socket, a magnetic pickup probe will extract them.
  3. 3
    Once the plugs are out, prevent any objects from passing down the spark plug ports and into the cylinders. Foreign objects could cause very serious damage to the engine. An easy way to prevent debris from entering is to insert paper towels in the spark plug wells.
  4. 4
    Loosen the harmonic pulley retainer bolt (21mm) but keep it "finger-tight" (snug - do not remove it at this time). Ideally, use a small impact wrench to loosen it.
  5. 5
    In a pinch, consider using the power of the starter motor to loosen the pulley bolt. The "bump method" should only be performed with the spark plugs removed and NEVER while holding the wrench by hand or foot.

    To "bump" the bolt loose, reconnect the battery, perform a momentary press of a "remote push-button starter switch". If none is available, wiggle the ignition switch to "nudge and thump" the pulley bolt a very small amount while a socket wrench is lodged onto the bolt as explained below (never held by hand or foot).

Timing marks, align timing, accessory belts,

  1. 1
    Cam shafts - Be careful not to disturb while working around them.
    Cam shafts - Be careful not to disturb while working around them.
    Barely loosen (break loose) each of the 11 bolts (10mm) connecting the Overhead Cam (OHC) valve cover to the engine. Loosen the 9 bolts around the edge of the cover that connect it to the block (one is on the very end). Two of those 10mm bolts are on the cover (one of these is about 3 times longer and was previously covered by the power steering hose removed earlier). The one in the center is about 4 times longer than the ones around the edges. Only when all are loosened should you finish removing all 11. If you do more than just break each of them free first, it can cause much difficulty in removal of all (and potentially damage the screw taps or worse).
  2. 2
    Remove the OHC valve cover, the top of the timing belt sprockets, and the cam timing marks.
  3. 3
    Align the timing marks on back of the cam sprockets lined up straight across. (Caution: be sure the negative terminal of the battery is disconnected - if you used the bump technique earlier, you may have forgotten to detach it again). With a wrench on the retaining bolt of the harmonic pulley aligned with the top of the engine head - at the same time line up the timing mark on the crankshaft harmonic pulley pointing straight up at the same time as the cams are aligned (or use the crankshaft key and slot later in the process when the harmonic pulley is off).
  4. 4
    On the right is the distributor (older models) with its cap removed to check that it is pointing toward the number one spark plug terminal to check that the timing is on the compression stroke.
    On the right is the distributor (older models) with its cap removed to check that it is pointing toward the number one spark plug terminal to check that the timing is on the compression stroke.
  5. 5
    Required: securely place a "plastic/rubber" stop-block (you may use a stopper from a wine bottle but not real cork which will crumble) to put it in place to jam the cam sprockets. Place the stop-block before releasing the tensioner pulley, or else when the timing belt is removed the cams will turn in opposite directions about two notches off TDC -- pushed by the valve springs pressure of the cam lobes.
  6. 6
    Loosen the passenger (if a left-side drive) front wheel lug nuts but leave them snug.
  7. 7
    Jack up the passenger side and use a jack-stand to support the car. Do not depend on the jack to support your vehicle. You will only be removing the wheel adjacent to the pulleys.
  8. 8
    Keep in mind that later you will need to support the engine with a jack - you may need an additional jack.
  9. 9
    Remove the plastic splash-guard cover under the engine which extends to cover the side of the wheel well. Watch your head.
  10. 10
    Support the engine securely with a scissor or bottle jack exerting only slight upward pressure with a strong piece of wood (longer than a brick) to protect the engine from the jack. The best place to support is the massive air conditioner bracket on older models. The engine supported is necessary to remove the motor mount between the halves of the timing-cover which prevents access to the accessory belts, timing belt and water pump. This removal will happen in a later step, block it up now.
  11. 11
    Remove the plastic top half timing cover by loosening 4 small bolts (10mm) near each corner. The two toward the firewall of the auto are difficult to reach and see. Use a short, small ratchet drive extension.
  12. 12
    Remove the harmonic pulley bolt (21mm) that you loosened earlier and remove the pulley. You can wiggle the pulley while gently prying and pull it off the crankshaft. If it will not remove, you may need to use a steering wheel puller or gear puller.
  13. 13
    Put the bolt back in to hold the sprocket on and ensure the sprocket key is always kept in its slot. This is necessary to remove the lower timing cover.
  14. 14
    Remove the retaining screws from the lower half timing cover (10mm). One is difficult to see in the middle of the cover, just below the motor mount.
  15. 15
    Remove the lower timing cover carefully - you have to maneuver it to clear the alignment pin-block (shaped like a small 2mm cube) just above the crankshaft sprocket that fits into place in the lower half cover. You cannot see it until the cover is off.

Removing engine mount

  1. 1
    Caution: Be sure you support the engine with a jack with just a little pressure upward so you can remove the motor mount on the belt end of the engine.
  2. 2
    Begin removing the motor mount by unbolting the 7 bracket bolts (17mm = 11/16 inch) with a strong break-over wrench with a cheater pipe on its handle to get more leverage and remove an 8th bolt which is the longer bolt that passes through the middle of the lumpy looking metal-rubber mount also.
  3. 3
    Find the "seventh" bracket bolt if not yet removed which was uncovered when you lifted out the heavy lump-like middle part of the mount.
  4. 4
    Remove the huge, oddly shaped motor mount bracket carefully from among the air conditioning hoses and power steering hoses by pulling them back "just a little," and yet do not damage the wiring and hoses.
  5. 5
    Remove the smaller "engine mount bracket" of the motor mount which is heavy duty steel and is still bolted to the engine block after you have removed the rest that was mounted to the fender area. You'll need the 17mm socket and a 3/8 inch ratchet with smaller cheater extension to loosen the bolt. 1/2 inch ratchet is hard to use between things in the tight areas. It is rather awkward to do.

Install New Timing Belt, New Tensioner, Idler, and the Water Pump

  1. 1
    Readying to remove the timing belt, you need to turn the timing belt tensioner pulley toward "counter-clockwise" with an Allen "el-shaped" hex tool that fits in a hole in the pulley to rotate it to be able to slip the belt off little by little.
  2. 2
    Turn (pivot) the timing belt tensioner pulley toward "clockwise" with the Allen hex wrench enough to take the tension off of the timing belt tensioner spring and then remove the spring with very long-nose-pliers.
  3. 3
    Remove the tensioner pulley by one bolt in the middle (14mm).
  4. 4
    Remove the "idler" pulley of the timing belt system (14mm).
  5. 5
    Remove the 4 or 5 water pump bolts which are hard to see -- (12mm) socket -- and a medium size ratchet (called 3/8 inch drive in the USA). Be careful because one bolt that is easier to see looks like it may be one to remove but its left of the correct one) and find and then loosen the water pump. Loosen it from the block by tapping it with a wooden block and a mallet hammer but if it does not come loose pretty easily -- check again for another bolt.
  6. 6
    Clean the engine block surface carefully where the water pump gasket will make contact for sealing well -- so carefully scrape off any pieces of stuck-on old gasket material corrosion, rust, or dirt to bare metal without gouging or roughing the metal. If your water pump used a metal gasket and it is still secure to the engine and in good shape, do not remove it. Just clean it up and mount your new water pump to it. The metal gasket is better than any new fiber gasket that might have come with your new pump.
  7. 7
    Put on the "new water pump"; follow instructions that came with it. Tighten 12mm bolts securely without over-tightening, ie: breaking one off. Start the bolts by hand; tighten them in a star pattern to minimize any warping. Seal the new gasket only onto the new pump with "gasket cement." Do not cement it onto the block. Put anti-seize grease on bolts. You can put an even coating of marine grease on the gasket after it is cemented onto the pump so it will not stick to the engine block.
  8. 8
    Install the "new timing tensioner" pulley and tighten its mounting bolt securely. Hook the new spring in the hole of the tensioner ear/tab and use the Allen wrench in the hole that is in the front surface of the tensioner pulley for that wrench to bring the spring clockwise to get the spring near and then hooked onto the pin that protrudes from the engine block just above the pulley. Be sure the spring is hooked into the groove on the engine pin.
  9. 9
    Install the new "idler pulley" and tighten the mounting bolt securely.
  10. 10
    Keeping the stop block in place to hold the sprockets aligned, Start the belt part way onto the "crankshaft pulley sprocket" and going counter-clockwise being certain to place the belt without slack onto the left of the idler pulley and across the tops of the "cam sprockets" and use the Allen Wrench to rotate the tensioner toward counterclockwise to get the belt on to the right of the tensioner, and work the belt the rest of the way onto the sprockets and both pulleys.
    Keeping the stop block in place to hold the sprockets aligned, Start the belt part way onto the "crankshaft pulley sprocket" and going counter-clockwise being certain to place the belt without slack onto the left of the idler pulley and across the tops of the "cam sprockets" and use the Allen Wrench to rotate the tensioner toward counterclockwise to get the belt on to the right of the tensioner, and work the belt the rest of the way onto the sprockets and both pulleys.
    Put on the "new timing belt"; follow instructions that came with it. (Like a 1 inch (25.5 ~ 26mm) open end wrench can be used to budge the cam slightly to get a cam timing mark back aligned while keeping the the stopper "jammed" (in to hold the sprockets) in place until you get the belt on and the tension spring on right. So, starting at the crankshaft sprocket place the belt a little more than halfway onto the sprocket and then going counter-clockwise making sure the belt is tightly against the idler pulley/roller as you slip the belt onto the cam sprockets and tight across between the cam sprockets when on both of them.
  11. 11
    Press the timing belt onto place while keeping the tensioner pulley out of the way using the Allen hex wrench toward counterclockwise for the pulley to be as far backed off as possible to allow the belt to slide on to the sprockets. While holding that hex wrench begin to work the belt in steps farther onto each sprocket until it is on all the way.
  12. 12
    With the Allen wrench in the hole in tensioner pulley for that purpose press it toward clockwise against the belt and press it in for a little tightening of the belt, and then release it slowly for the spring to bring it back into position.
  13. 13
    Remove the "stopper block" from the cams -- before you put on the top half-cover on the timing belt area.

Reassemble

  1. 1
    Assemble parts mostly in reverse order of the removal and tighten bolts properly.
  2. 2
    Install "lower-half cover" of the timing belt and put the bolt and especially the one in the middle which is hard to see just below the motor mount bracket.
  3. 3
    Remove the big bolt for a moment from the crankshaft sprocket to then put on the crankshaft pulley.
  4. 4
    Put the harmonic crankshaft pulley on be sure the pulley key slot aligns on the slot and key of the crankshaft that must be aligned into the slot in the pulley. Put the big bolt back with the washer/disk and tighten it securely.
  5. 5
    Install only the third part of engine mount (the smaller bracket) that bolts to the engine block (for now) -- because it will be partly covered by the timing covers. Use the large ratchet or medium sized ratchet (3/8 inch) with a cheater extension to tighten the motor mount bracket securely and also to reinstall the other parts of the motor mount later (before you remove the jacks).
  6. 6
    Reassembly is mostly in reverse order of the removal of course such as the bottom and then top half timing covers, the alternator belt, power steering bracket and belt, adjust the those belt tensions, put on OHC valve cover
  7. 7
    Install spark plugs with the spark plug cables in the correct order.
  8. 8
    After all the miscellaneous reassembly is done, now install the motor mount bracket securely with its 3 bolts and 2 nuts onto the car fender and the motor mount itself with the long bolt and nut and 2 nuts that attach it to studs on the part of the bracket that is attached to the engine block.
  9. 9
    Replace the under engine/wheelwell side cover and put on the wheel but re-tighten it after it is on the ground, later.
  10. 10
    Prepare to remove the engine supporting jack, by first verifying that the motor mount brackets and motor mount are installed and all the bolts are tightened, raise the car a little and remove the jackstand and lower the car, and remove wheel chock blocks. Almost finished.
  11. 11
    Remove the "radiator cap" and refill the radiator with coolant (note: some cars have a remote tank with a cap but no radiator-cap.) and then refill the coolant system and refill the overflow tank, bounce the car on the side where it is not on the jack and add more coolant; do that a few more times. Check for coolants leaks.
  12. 12
    Clear away any tools, etc. before starting the engine.
  13. 13
    Reconnect the battery negative cable.
  14. 14
    Check for coolant leaks, check all other fluids, and leave the radiator cap off temporarily to recheck so you can top-off the coolant level after starting the engine.
  15. 15
    Let it idle while finishing filling with coolant and put on the radiator cap, and be sure that the car is otherwise road worthy.


Tips


Warnings

Things You'll Need

Posted by Raj at 3:29 AM
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