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

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

Steps

  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.
    • Caution: When reassembling parts and torquing bolts to complete the installation, always use the "smallest workable ratchet, break-over wrench and/or cheater (leverage extension)" correctly to not over-tighten (over-torque) bolts. Over-tightening will break off a bolt-head, requiring much extra labor (more detail in the Warnings section).
    • You actually might have to remove the engine to extract a broken bolt. Be cautious to avoid exceeding the torquing specifications - the cost of a broken off bolt-head and even falling into a cylinder is very high.
  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. 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).How?:
    • Change the timing belt, timing belt tensioner and its idler pulley. The diagram shows the following numbered parts: (1) retaining bolt for the harmonic pulley, (2) a large thin washer (the guard for the crankshaft opening) found behind the harmonic pulley (harmonic pulley not shown), (3) both halves of the timing covers, the belt (sort of tee-shaped, not numbered), and (4) the tube for the oil-dipstick (its retained by top left bolt of upper-half, timing-cover).
    • Caution: this is an interference engine meaning that the valves and pistons will come into contact, interfere and may damage the engine in case (if) the timing belt were to break or slip on cam(s) sprockets or the crankshaft sprocket (more detail in the "Warnings Section").
  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. 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 1998 and after 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]
    • Caution: Disconnect the negative battery terminal so your engine can not be accidentally turned and so it can not be started in error, also remove the spark plugs, before doing dangerous work (their removal releases compression which makes the engine turn easily, as well as work being safer).
  6. Drain all the coolant from the engine and keep it to use again or dispose of it legally, no matter how little.
  7. Remove the accessory belt(s) for the alternator, power steering, air conditioner, etc:
    • Older models with two accessory belts have lock bolts on the tensioner bolts that must be loosened before you can turn the long tensioner bolt. You will need to loosen the lock bolts a turn or more and then loosen the tensioner a good number of turns until you can get enough slack to remove the belts.
  8. Remove the three bolts holding the power steering pump 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. 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.
    • Do not pry or force the belts to get them off. loosen the adjustment bolts more than you expect - new belts will be much tighter than broken in ones. By prying off belts, you risk damage to various parts with no saved time or effort.
  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. 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. 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.
    • If you intend to reuse the spark plugs, be careful in their extraction. Careful examination of the plugs may indicate the condition of your engine - repair manuals usually have a chart explaining what conditions of used spark plugs indicate.
  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. 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. In a pinch, consider using the power of the starter motor and power "bump method" to loosen the pulley bolt. This 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 longer handled socket wrench is lodged onto the bolt as explained below (never held by hand or foot).
    • Caution: do not hold the wrench by hand if you are power bumping it loose with the starter motor. Position a break-over wrench with about 2.5ft (75cm) cheater pipe (like 1 or 1.5 inch steel conduit tubing) extending it and positioned at about a 45 degree angle down toward the front of the car to be held firmly against the floor or earth, blocked in place with large stones, or by being inserted in an opening of a concrete block and blocked in with heavy toolboxes to keep the cheater from sliding out. Alternatively, secure the breaker bar by positioning it below the tie bar secured to the tie bar with a screw clamp. Make sure it is tightly secured so it will not move. This method does not require any blocking in of the cheater bar.Then see whether it loosened the bolt--but if not then check that its still on correctly and lined up and try it again. It may loosen on the first two or three tries, when it loosens enough you'll probably hear a something like a "zinging/whizzing" sound. So quiet the area so you can hear any sounds.
    • Caution: Disconnect the negative battery terminal after this technique so your engine cannot be accidentally turned away from top dead center (TDC) by the starter motor, potentially damaging various engine parts.

Timing marks, align timing, accessory belts,

  1. 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. Remove the OHC valve cover.
    • WARNING: Do not turn the engine using the cam timing sprockets, or by their retaining bolts, or by pulling on the timing belt. The engine should be easy to turn with a socket wrench on the crankshaft bolt since the spark plugs are out and no cylinder compression resists your effort.
  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. Check that the cylinder one is at Top Dead Center (TDC) on the compression stroke.
    • Caution: the TDC marks can be 180 degrees off even though the crankshaft mark or crankshaft key is pointing straight up (when it's at the top of the exhaust stroke).
    • Caution: check that timing is at TDC of the compression stroke - find the marks on the back of the sprockets and align them with the edge of the engine head. Older models have a distributor - remove the distributor cap to see if it is pointing at terminal number one when the mark on crankshaft pulley shows it is at TDC. If it points to the opposite side of the distributor, turn the crankshaft slowly 360 degrees to bring it to TDC (at the top of the compression stroke of cylinder 1).

      Newer engines are 'distributorless', still the correct TDC can be found while the harmonic pulley timing mark is approaching TDC. This is done using the compression stroke air pressure measured in the "number one spark plug hole" by a "compression gauge" to know when the piston is on the compression stroke and then turning slowly and carefully to exactly the TDC as shown by the crankshaft and the cam sprockets timing marks. Compression pressure means that the piston in cylinder one was on the compression stroke not the exhaust stroke (which also comes to TDC, in all 4 stroke engines).
  5. Required: securely place a "rubber" stop-block (you may use a rubber stopper from a wine bottle but not made of 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 on the cam lobes.
  6. Loosen the front wheel lug nuts on the right-hand side of the car, but leave them snug (the same side the engine belts and pulleys are on).
  7. Jack up the that side and use a jack-stand to support the car (place jack and stand on strong concrete or stone base). Do not depend on the jack to support your vehicle. You will only be removing the wheel adjacent/next to the pulleys.
  8. Keep in mind that later you will need to support the engine with a jack; so you may need an additional jack.
  9. Remove the plastic splash-guard cover under the engine which extends to cover the side of the wheel well. Watch your head.
  10. Support the engine securely with a scissor or bottle jack exerting only a little 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 support 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. Remove the tensioner pulley by one bolt in the middle (14mm).
  4. Remove the "idler" pulley of the timing belt system by one bolt in the middle (14mm).
  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 to the left of the correct one). Then loosen the pump 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. 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 but not 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. Put on the "new water pump"; follow instructions that came with it. To tighten 12mm bolts securely without over-tightening, breaking one off: Start the bolts by hand; first just barely snug them, then gradually tighten them evenly, in two for three passes, in a star pattern, back and forth across, from side-to-side to minimize any possible 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.
    • Or if you prefer to use a silicone gasket maker, then apply a small even bead but not an excessive amount that could squeeze out and cause plugging/blockage of coolant passage-ways in the engine or radiator.
  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. Install the new "idler pulley" and tighten the mounting bolt securely.
  10. Put on the "new timing belt"; follow instructions that came with it. (Like a 1 inch (25.5 ~ 26mm) open end wrench on special hex-part of cam along the middle length of the cam can be used to budge the cam just slightly to get a cam timing mark back aligned while keeping the the stopper "jammed" in (to hold the sprockets/cams) in place until you get the belt on and the tension spring on correctly. 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. Press the timing belt onto place while keeping the tensioner pulley out of the way enough, using the Allen hex wrench toward counterclockwise for the pulley to be as far backed off as possible to allow the belt to slide onto 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. With the Allen wrench in the hole in the 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. Remove the "stopper block" from the cams -- before you put on the top half-cover on the timing belt area.
    • Hand rotate the crankshaft two times around, using a wrench on the crankshaft sprocket bolt, then check to see that when the crankshaft key is aligned, then the two cam timing marks are still aligned as described earlier. Be sure one or both isn't off by one notch or something. If it is not aligned properly then remove the belt, carefully realign all 3 marks and reinstall the belt, and double-check it again.

Reassemble

  1. Assemble parts mostly in reverse order of the removal and tighten bolts properly.
  2. 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).
  3. 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
  4. Install "lower-half timing-cover" and put in the bolt and be sure to put in the one in the middle which is hard to see just below the motor mount bracket.
  5. Remove the big bolt for a moment from the crankshaft sprocket in order to put on the crankshaft pulley in the next step.
  6. Put the harmonic crankshaft pulley on, being sure the big disk is in place before the pulley. Align the pulley slot with the key (on the crankshaft) that must be placed into the slot in the pulley. Put the big bolt back with the washer and tighten it securely.
    • Tighten and torque the harmonic crankshaft pulley bolt while you hold the pulley with a bar between bolts placed in the "puller bolt holes" of the pulley, or as best you can hold it without damaging it, and torque it to about {{safesubst:#invoke:convert|convert}} pounds.
  7. Install spark plugs with the spark plug cables in the correct order.
  8. After all the miscellaneous reassembly is done, now install the motor mount bracket securely with its 3 bolts and 2 nuts onto the inner fender-well -- 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.
    • Hint: You will need to pull a little on the hoses and move the wiring around gently to work the big mount bracket into its place and yet not damage the wiring and hoses. It's tricky, so be patient.
  9. Replace the under engine/wheel well side plastic cover and put on the wheel but finish/re-tighten it after it is on the ground, later.
  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. Remove the "radiator cap" and refill the radiator with coolant (note: some cars have a remote tank with a cap but no radiator-cap), refill the coolant system and 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. Clear away any tools, etc. before starting the engine.
  13. Reconnect the battery negative cable.
  14. Check for coolant leaks, check all other fluids, leaving the radiator cap off temporarily to recheck so you can top-off the coolant level after starting the engine.
  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

  • You should get a good repair manual with pictures to help you with this. It may not have very detailed instructions, but pictures and labeled parts in the pictures and their recommended order of the processes may be very helpful.
  • Do not use this guide as your only reference. You may encounter issues or problems not covered in this article.
  • This repair is involved (complicated). If you are not a fairly experienced mechanic, consider taking it to a shop -- or get a good helper who will spend several hours actually paying attention/and working, and discussing steps (but taking less time, if one of you were experienced).
  • If a helper has smaller hands (and/or longer fingers) to reach into tight spaces to insert screws, and if the helper is pretty sure of how to do it -- all of that may help greatly.
  • It is important to remember where various sizes and lengths of bolts came from (and go back in) and the tool(s) that you had to use.
    • Keep groups of bolts together for each part and remember the tool(s) that you needed for the dis-assembly/and later re-assembly.
    • Break-over wrench is used to "break loose" the tight bolts and to not break your ratchet instead.
      • Put unused tools away to keep down clutter and confusion.
    • Think as you do dis-assembly about recalling how your fingers and a wrench barely fitted into tight spaces -- and how you maneuvered them for dis-assembly -- can help you reassemble parts in problem areas.

Warnings

  • Do "not" rotate the crankshaft or cams while the timing belt is off or you will do severe damage as this is an interference engine.
  • Disconnect the negative battery cable and the spark plug cables at the spark plugs before putting your hands in dangerous places or doing any removal of moving parts or their covers or even brackets.
  • You actually might have to remove the engine to extract a broken bolt -- if you break off a screw or bolt in a tight spot when you are tightening them.
  • Coolant (antifreeze) is poisonous to fish, unsuspecting domesticated animals and children because it looks, smells and tastes okay, but it is lethal/deadly. It should be stored or disposed of properly as a hazardous chemical.
  • Caution: if you remove the spark plug cables completely then understand that firing order is "not" 1, 2, 3, 4, but may be 1, 3, 4, 2 and so first appropriately number and label on or next to the "mixed up" ignition coil pack terminals (or distributor on older models) with the correct cable number -- and start replacing them at the correct terminal or plug on the coil pack/distributor.
    • It is very important to be perfectly in that special order. Numbers may be formed or stamped on OEM coil, but may not be on after market parts.
  • Avoid breaking off a screw or bolt or stripping bolt their threads during reassembly by using small, medium and large ratchets correctly (use the smaller ratchet that will do the job to not over torque small and medium bolts) to get the parts tightened adequately -- but a broken bolt would have to be drilled (like hollowed out) and then an extractor tool used; so use the:
    • 1/4 inch ratchet for small bolts (like 8, 9 or 10 mm hexagon [hex] heads) to not break them off,
    • 3/8 inch ratchet for medium sized hex bolts (12, 14 or 15 mm) to not break those (consider using this one with a "1/4 inch adapter" for small bolts because the adapter may break before the bolt; you hope...),
    • 1/2 inch ratchet for larger sized bolts (17 mm, etc.) to adequately tighten but not break those (the ratchet names are what they are called in the USA, by inch sizes).
    • Decide if a torque wrench is desirable or necessary -- and it is recommended -- to more accurately tighten bolts (if you decide that you need that kind of help) to check the tightness without over tightening.
      • 3/4 inch break-over ratchet would not be needed for this repair except "optionally" on the retaining bolt (21mm, 13/16 inch) on the harmonic crankshaft pulley.
  • Why change the water pump ("unless" it were changed recently): that's because the rubber seals of the old water pump get brittle and crack from engine heat and re-cooling -- and coolant washes out grease, so change it.
  • Bearing grease dries out and the bearing, overheats, locks up (seizes), if the water pump and timing belt pulleys are not changed periodically.
    • There is no way to re-lubricate the bearing (sealed up and "permanently" lubricated) -- just waiting to fail.

Things You'll Need

  • Stop-block for the cam sprockets
  • New timing belt, with matching new tensioner & idler pulley
  • New water pump, gasket and gasket cement
  • New accessory belts, it old
  • Repair manual covering your car model, for this engine
  • Torque wrench to accurately tighten bolts
  • Pneumatic wrench (optional) to do up main harmonic pulley bolt
  • Small, medium and large ratchets (1/4, 3/8 & 1/2 inch in the USA)
  • Sockets, not many deep-well sockets except to reach odd places and on the motor mount stud (several 17 mm)
  • Spark plug socket (16mm, 5/8 inch)
  • Short, medium and long socket extensions (for various motor mount bolts)
  • Adapters for ratchets, extensions, and sockets as desired or needed
  • Smaller, medium and larger "cheater" extensions for handles of break-over and/or ratchets
  • Break-over socket wrench (breaker wrench) for "breaking loose" bolts and nuts (and protect your ratchets from breaking)
  • Cheater extension for break-over wrench handle
  • Penetrating oil for loosening bolts and nuts
  • Compression gauge (for newer cars without a distributor)
  • Wheel blocks (chocks)
  • Anti-seize grease for bolt reassembly, particularly water pump bolt-threads
  • Car jack(s) and jack stand(s)
  • Scissor jack or bottle jack for engine support
  • Wooden piece to protect car metal and paint from the jack

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