Changing Your Car's Timing Belt and Water Pump




About: Engineer making renewable energy products for African entrepreneurs.

I drive a '97 Mazda 626 - 4 cyl. Changing your timing belt is not a small task, and it will not be identical to your car (unless you drive a 4cyl 626, mx6 or ford probe with an FS series engine). I wrote this for my 626 community and I am copying things here (so some stuff might sound a bit off)....

Welcome my fellow auto DIYer. First, I commend you for taking on this task, I will rank this as one of the more difficult things in the realm of the 'shade tree' DIYer. The hardest thing to deal with is tight spaces, other than that the task is straitfoward for the most part

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Step 1: Background Parts and Tools

First off, this is a non-interference engine design. That means that the lowest point that the valves reach is HIGHER than the highest point the piston can reach... A pretty nice idea because if your timing belt breaks for some reason, you'll avoid the cost of new valves and tearing down the head.

I did not have to replace my T-belt, my water pump died and because replacement involves removing the T-belt, I did so as a precaution.

Tools and Parts:

# New Timing Belt
# New (or reman) Water Pump
# Tensioner Spring
# Tensioner Pulley (if higher mileage)*
# Idler Pulley (If VERY high mileage) *
# VC Gasket*
# Gasket Scrapper
# Torque Wrench **
# Jack, Stands, Wood Blocks
# Black RTV sealant (I do not recommend "Ultra Black")
# Metric Allen/hex Key set (Or 1/4" - may require sanding to fit)
# Plastic Baggies and Sharpie
# Piece of Cardboard
# Feeler Gauge Set ***

*If you have the ability, wait and see if the old one is still good - I changed at 74K miles. My tensioner had play in the bearing but my idler was in great shape.
** Highly recommended.
*** Perfect time to check your valve clearance for you guys with solid lifters (98+)

The 93-97 model years used hydraulic lash adjustment (HLA) as opposed to solid lifters used in the 98-2002 design. Both work just fine, but HLA's can clog easily causing valve tap. Its just cosmetic and several frequent oil changes clear it up.

Step 2: Prep Work -- DO READ THIS

Make sure you have a lot of time (like a weekend). If you are changing the water pump, flush the system with water - do't forget the heater core. You want only water in the cooling system because when you remove the water pump, you probably will have a mini flood eject from the block. DO NOT change the oil (yet) - if any debris falls into the system, you want to catch it early (and not 3K+ miles later). Allow the engine to completely cool down.

Use the plastic baggies and sharpie to mark EVERY fitting you remove. This will save you a great deal of time.

I had to wait for a part from the stealership (1 stripped waterpump bolt). It took 4 days (I was leaving for school on the 5th day). Because of the organization, I was able to fully reassembly (minus setting the T-belt on the cams) within an hour (maybe slightly over).

Step 3: Getting Started

Picture 1:
Raise and support the vehicle on jack stands. I supported my car on the frame of the car just behind where the front unibody attaches to the main beams of the car (sorry, not sure on the technical wording of that). You'll see it, just two bars about the same width as your jack stand cups. That is not oil from my car - that was from replacing the timing chain on a '93 saturn SW2, what a mess it was.

Picture 2:
Remove the Right wheel. Remove the splash guard (note the rust from using 100% water for about 600 miles). Tip Put the Lugs back on the wheel to protect the threading and to keep track of them.

Step 4: Removing the Belts

Sorry I neglected to take pictures of this - but I can offer help if you don't know how. First the PS/ac belt. Remove the PS belt guard with a philips screw driver head, there are two bolt/screws.

If you look just in front / below the PS pump, you will see a long threaded bolt. That is the bolt that apples tension to the PS pulley. Just below the PS pump is another bolt like thing. That locks the PS pump to the tensioner track. First you need to loosen that bolt with a 14mm wrench. Once it is a little loose, look at where the PS bracket attaches to the head. There is another 14mm bolt that goes through the head and attaches to the PS pump support bracket. Loosen that a few turns. Now, with a 14mm wrench, begin the slow process of loosening the pump by turning that bolt. Once enough tension has been relieved remove the belt.

Now, without disconnecting hoses, remove the PS pump. Again I am sorry, I forgot to take pictures of this step. Don't forget to remove the two bolts that secure the hose to the VC.

Step 5: WP Pulley and Belt

Picture 1:
DO NOT DO WHAT I DID. I removed the belt before dealing with the pulley. It is near impossible to take the pulley off without the belt holding it in place. Using a 10mm wrench, loosen the 4 WP pulley bolts. You may have to turn the crank by hand in order to access all of the bolts.

I went a little out of this order to make pictures easier That bolt hole in the top right of the picture is where the PS pump pivot bolt goes.

Picture 2 and3:
Once the pulley bolts are loose, we now can remove the belt. It took me a little bit to find the alternator pivot bolt because its hidden for some odd reason. Again, I did not take pictures for this step (related to the last step). But behind that arrow a little bit, you'll find a bolt on a bracket. Use some common sense to make sure you found the right bolt. Its gonna be connected to the alternator somehow. Loosen that bolt, then loosen the tensioner bolt on the alternator (again, 14mm)

Step 6: Removing the VC

Now the fun stuff :D

Picture 1:
Look at the bolts on the VC. Notice how they all have the number '6' or '9' on them (can't tell which). Well, thank you mazda for number coordinating your fasteners. If I recall, '6' (or '9') means 10mm wrench wink.gif So take your 10mm wrench and remove the bolts. Press each one into a piece of cardboard. I drew a mini picture of the top of the engine so I would not forget where to put the bolts. Some are different lengths - mark those with an 'L' just to make sure you have everything right.

Picture 2:
Tap on the VC with a rubber mallet a few times to release the bond of the gasket. Remove the breather hose and PCV. Make sure the PS hose is out of the way (you did remove the PS pump right?). Then pull the cover straight up (so you avoid hitting the cams/sprockets). I use 100% synthetic oil. The inside of the VC was a beautiful amber - only slightly darker than the oil

Step 7: Checking Valve Clearance

If you have a 98+, this is perfect opportunity to check your valve clearance. Just use a feeler gauge and check the clearance for each number. Remember, start with slightly larger, then use a smaller feeler until it just fits. Check your manual for clearance numbers. I have a '97 which uses hydraulic adjustment - so this step does not apply to me.

Step 8: Remove the Top Right Motor Mount

Take a block of wood and put it on top of your jack. Lift the engine (place the jack on the oil pan) a tiny bit (as soon as you start seeing the engine going up). Using a deep well socket, unbolt the two block-mount bolts. One of the bolts has a ground, make sure to keep the washers and place the ground wire off to the side. If a stud comes up too, don't worry - just place it in the baggie. Next, remove the bolt that goes right through the whole mount/support bracket. Using a long extension is very usefull if you go UNDER the power steering hose. Remove the bolt and take the mount out by lifting up - be carefull around the a/c lines if you have them

Step 9: Removing the T-belt Covers AND Crank Pulley (aka Damper).

I am pretty sure all of the bolts use a 10mm wrench. Start with the top cover. Remove all bolts pull the cover away from the head (there are metal guides to keep it aligned) and lif the cover straight out.

Remove the crank pulley bolt. Place your wrench on the bolt and wedge it into the ground, if its too high off the ground, use a length of pipe as a cheater bar. Now, blip the starter for a second. This will break the bolt free and make your job 2000% easier wink.gif Once the bolt is off, remove the pulley. Be patient, its on a keyway and is a very low tolerance item (tight fit). Wiggling back and forth a lot will help it come free. DO NOT use a lubricant as you may get it in the T-belt area place biggrin.gif Careful, that pulley is heavy for its size.

Now, we can remove the lower T-belt cover. Again remove all bolts. Tip For this bolt, use a deep well socket wink.gif It makes the job easier. Remove the cover though the bottom.

Now we are all ready to go about our business of taking the pump and/or T-belt off.

Step 10: WP Removal

Picture 1:
First you need to remove the idler pulley as it is attached to the water pump. You will also need to remove the PS tension guide bracket as it is also bolted on to the water pump.

Clear away everything from under your car - it will get wet otherwise. Tip Learn from my mistake, do this from above - unless you need a shower.

5 Bolts secure the water pump to the block. Remove each one and place them in a bag. The pump will probably be seized on the block... Tap on the pump and it should break free no problem. Remove the pump. The factory gasket is made out of metal, so it should come off easily. Allow the surface to dry. Wipe the mating surface clean and apply some gasket dressing to the surface of the new gasket. Carefully bolt on the new pump. Put two bolts in the pump and navigate the pump onto the block (the two bolts keep the gasket aligned). Tighten the bolts using the star method (as if you were tightening your wheels) - check the manual for torque specs.

Picture 2:
This is the old and new pump comparison. There was quite a bit of play and a lot of resistance.

Picture 3:
I took this chance to clean up the rust coating. I used a nylon brush and water. I also flowed water through the top radiator hose to backflush the head and wash away the scrubbed rust powder. I also cleaned the control arm and splash guard - anything that had rust on it.
Tip Go VERY slowly when first threading the water pump. cross thread and screw up one of those bolts will be a delay of a few days. A new bolt is $4.13 from the dealer and it took 4 days for it to arrive.

Step 11: Removing the T-belt

Picture 1:
Hand turn the crank until the I and E align and the crank pip/keyway aligns with the notch on the block. When I say hand crank, I mean put the crank pulley bolt in and turn with a wrench. At this point, you'll probably want to remove the spark plugs so you don't have to deal with cyl compression forces. Remember, you will have the belt on at this point. If you are going to be using the same belt, mark the direciton of the belt with a paint pen or sharpie (never reverse the direction once installed).

Picture 2:
This is not too bad, but it is under a lot of tension. First find the correct hex key. If you are changing the tensioner pulley, find something that fits it. These instructions are not the same as the manual, but it works well. First loosen the tensioner pulley bolt. Using your hex key, turn the tensioner to the right until the spring has the least amount of tension on it... Then, reach down and pop the spring off the hook pin. You should have this (plus the belt):

Step 12: OK, Now the Hard Part. Putting the Belt Back On

I recommend finding a friend. Because you are a DIYer, you won't have a camshaft holding tool the cams are no doubt going to pop out of alignment because of valve spring pressure. What complicates things further is that the intake cam wants to spin clockwise (when facing them head on) while the exhaust cam will pop in the counter-clockwise direction. My hands were full on this one because I did not have a friend available - this is a tough one.

With the tension off the belt somewhat, remove it from the cam sprockets. Some force may be required if its on there tight.


Part A Replace the tensioner, spring and idler as necessary
You really must replace the spring, other than that, make sure these two parts are torque'd down.

Part B Get the belt ready
Get the belt ready for putting it on the sprockets. Just weave it around the motor mount post and just let it sit for a few minutes while you do other things

Part C A few adjustments
Place your hex hey in the tensioner. Adjust the intake cam so the I pip mark is at 90 degrees as shown (this is cyl 1 TDC). Carefully remove your wrench so that it does not pop back out of alignment. Be careful at this point, bumpint the car can pop that cam. Now, 'thread' the belt on the crank sprocket. Pull straight up to keep the treads in the sprocket.

Part D The Intake Cam Sprocket
Guide the belt onto the tensioner. Turn that hex key counter clockwise to give yourself more room to move the belt (hold in position). Now, pulling hard on the left side of the belt (and some tension on the right side to keep the belt from turning the crank), 'thread' the belt on to the intake cam sprocket. Only do it about halfway on to make the exhaust side easier. Hold the right side tight, because if you pull on the left side while the treads are in the sprocket, it will pop out of alignment. The idea is to have enough force on the right side of the belt to keep the intake sprocket aligned by not letting the crankshaft sprocket turn ohmy.gif

Part E The Exhaust side
You can now let go of the tensioner hex key you had there, just leave it alone for now so you are not distracted. Take your wrench and turn the exhaust cam clockwise until the 'E' pip mark aligns with the intake 'I' pip mark. The mark on the exhaust sprocket will be at 270 degrees (this is taking straight up to be 0 and turning clockwise). Now, get a few of the belt treads on the sprocket and push down hard so it does not slip. Hold tight.

Part F Popping the belt on
We are gonna do something a bit weird. We are going to use the intake sprocket as a guide to 'thread' the exhaust side on. Place your wrench on the exhaust sprocket bolt and turn it as hard as you can in the clockwise direction. Turn it until the belt 'hops' onto the sprocket. This is why we only did 1/2 of the belt on the intake side biggrin.gif Once the belt is fully threaded (but not on all the way just yet), use your hands to push the belt onto the idler pulley. Take a quick rest if your arms are tired tongue.gif

Part G Aligning the Belt
The belt will slide as it is. Remember that the sprocket before the current one is the guide. So, using a soft mallet, tap the belt a few mm at a time on the intake side - then hand crank the belt. You can do the same thing on the tensioner pulley location, idler pulley location and crank location. Just don't go too far at once to avoid stressing out the belt. Once it is on nicely, hand crank until you see how everything aligns. If the crank notches align when the intake/exhaust pips align, you did an excellent job. Hand crank at least 4 time just to be sure.

I used my jack handle to tap everything in.


If you have an assistant, use their steady hand when you feel you need a third, fourth or fifth hand. This is the method I came up with. I've never done a timing belt before so I had no clue. And at the time the site was down for us regular members ( :/ Once I did this, it took me one shot to get it aligned right, but the cams do like to pop a lot - so that was a delay.

If you want to make your own cam holding tool, you can. Just use two wrenches that fit the sprocket bolts. Drill a hole in the middle and put a bolt and nut through it. Put the wrenches on the cam bolts, then tighten the bolt in the wrenches really really tight... voila.

Step 13: Putting It Back Together - and All Important Tips/advice

Don't forget any wire guides (I forget the crank position sensor).

DON'T BE DISCOURAGED IF YOU DON'T GET THE T-BELT ALIGNED THE FIRST TIME. Almost no one does, I got it rather quickly (not too common though). Just don't be afraid to redo it if you suspect its off.

Just a few points to remember

When putting the PS pump back on. Install the bracket (that screws into the WP). But leave the bolts really loose. Then put the pump into place. Looking at it head on (standing on the right side) the order of metal parts at the bottom should be:

1. Guide Bracket
2. PS Pump Mount

It took me awhile to figure that out when the pump would not align to the mount bracket.

Don't overtighten the belts. I did and thought I screwed up somewhere. Loosened it up and everything was cool.

When tightening the WP pulley, do so in a criss cross method to make sure it is on even and won't rub the T-belt covers.

The lower T-belt cover will be a bitch to get back in place. This is normal, don't worry.

When putting the MM back on, lift the engine until the mount studs are vertical, then just a tad bit more. This will make installation easy.

DO NOT RUSH- More mistakes will come of this.

Make sure to put RTV sealant where the camshaft arches begin/end. Give it 24 hours to cure. Make sure the mating surface on the VC is clean and free of any oils and other debris. After a week of driving, change the oil or at least the filter to make sure no dirt or anything from having the VC open is floating around.

I may have forgotten something, but I will go back and correctit eventually - in the meantime, just post anything you see that I overlooked.

So, after all of that, she started up no problem. For about a 1/2 second she was a little confused because the crank position sensor was not where she remembered it was (this according to Mazda). I turned the key and it blipped the starter, paused for a second, the turned over and started as if nothing happened


Step 14: If Only Doing the Water Pump

If you just want to change the pump and don't want to deal with the belt biggrin.gif

As the idler pulley is attached to the pump, you'll have to hold back the T-belt with a bit of wire. Once the belt is taken care of, just remove the water pump as instructed above. The spacing is more tricky, but it should not be as involved as doing the T-belt. Thanks Sailor626 for getting the picture :D

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    31 Discussions


    7 years ago on Introduction

    Thank you for this article - it was a real life saver when I had misaligned the intake and exhaust cams during a timing belt change :-)

    I've added a picture I found to be missing - it shows exactly how the I and E pip marks should match when cylinder one is at the top position.

    I've also added a picture of a small tool I had to make in order to loosen the bolt on the crank - that one did cause me quite a bit of trouble. The hole in the center is approx. 30 mm to allow the 21mm top to grab the bolt while the tool holds the pulley in place. The two 8mm bolts fastening the tool to the pulley are approx. 20mm in length.


    10 years ago on Introduction

    I have a Mazda 626 1997 I changed my water pump (before found this website) and the timing pulleys slipped (I didn't mark them) I tried to reline. The car will not start at all it makes a wierd hum noise. Could this be due to the fact the belt is not a lined or is it probably a different resin?

    3 replies

    Reply 9 years ago on Introduction

    Seriously, this is a very important issue! If your timing belt slipped, it means the valves are not coordinated with the piston in travel. As you may be able to imagine, the piston will hit the valves, ruining both. Don't start it, and if you did, you probably screwed it up already. I wish you good luck and I hope the bill is not too expensive (though I fear it will be). The easiest way to realign would be to take the plugs out of the cylinders. Put something soft like a straight stick in a hole so it rests on the piston. Take the valve covers off. Now, using a screwdriver, slowly turn over the engine so that the piston is at the top of the cylinder. If the piston is at the top of the cylinder, PAY ATTENTION TO THE VALVES. If the valves are opened, you will damage the engine. You need the piston to be at the top with no valves opening, getting ready to open, or being open. No rockers should be moving above that cylinder! After you have the piston to the top of the compression stroke, and you know it is the correct stroke as verified by the points on a distributer or another method, you can fix the valves to be closed fully over that cylinder and then reattach the timing belt. So the piston will be at the top of the cylinder, end of it's compression stroke, and the valves are all closed with the points connected ready to fire the spark plug. This should align the belt again. Like I said, the engine is most likely messed up if you started it anyway and will require work and rebuilding of the pistons and valves. Hope it helps. I am not responsible for what you do with my advice :) *I think this is a good method, correct and all. I am sure someone will chime in to say it is flawed if it is*


    Reply 8 years ago on Introduction

    I know this is a way late comment but not all cars will bend their valves and such when a timing belt slips or breaks.

    I believe they are designated "interference and non interference" engines. In Certain engines like the older mazda 1.6l if your belt breaks or slips your car won't run but it won't damage anything.


    Reply 9 years ago on Introduction

    Point 1: Screw Driver trick - do it for cylinder # 1 Point 2: The FS engine is non interference. By design, the piston can never hit any valve while in any position. If you were to take apart the engine and look at the piston design, you'll find relief cuts in the top of the piston to allow valve clearance. Point 3: Add some space to your replies - it makes them much easier to read ;)


    8 years ago on Introduction

    I know I'm chiming in late, but...
    I just replaced the timing belt and water pump on my Honda Pilot (3.5l VTEC). Anyone getting ready to save money by doing this themselves should be warned - the crankshaft pulley bolt does NOT want to come off! I discovered that Honda's use some type of metal or coating on the thick washer behind that bolt that essentially fuses itself to the crankshaft over time. I had to heat mine with a propane torch for about 10 minutes before I could get it to budge. Even then, I was using some pretty serious leverage to get enough tourque on the bolt. Bottom line= heat the bolt and washer before you start wasting your energy trying that bolt.

    P.S. The special Honda tool sold to keep the pulley in place was useless to me. I just wedged the flywheel as suggested by Chilton's.

    Hope this saves someone else some time/frustration/pain/cursing, etc...

    Very few places can properly work on the internals of the rotary engines...apex seals are the main issue I have been told. That being said I think the rotary should be used much more. Not sure why Mazda decided that the new "Renesis" Rotary they are using in the RX-8 didn't need a turbo but whatever.

    You can turbocharge them but they are high compression engines and you risk blowing a seal. They are pretty straight forward to rip apart and put back together though.

    No, not really. Just making sure there is enough clearance on each side and aligning the side seals, which isn't very hard.


    Reply 9 years ago on Introduction

    One of my cousins in Saudi Arabia owns a garage that tunes cars and he received a mazda and told the owner " OK, I'll get it done in a few weeks" he then opens the hood and looks up at the owner and says "What the hell is that? I can't do anything to that!" End of story, just goes to show, rotary engines are not very popular in saudi arabia:P


    9 years ago on Step 4

    do you know of any website that can provide a picture of this step, or can you send me a pic. I am currently trying to replace the timing belt myself since its expensive for me as a college kid to have it fixed.


    9 years ago on Step 5

    how long does it take to replace the water pump and the 2 belts? im taking it to a garage cause i cant get it fixed and liked to know how much id be looking at spending. its 35 an hr i heard it takes about 3 hours for a skilled mechanic. please help me out thank you

    2 replies

    Reply 9 years ago on Step 5

    Mechanics do jobs "by the book" - there's literally a book stating how long  job takes (for billing and etc.). So if a mechanic can finish a "1 hour" job in 30 minutes - they'll charge for one hour plus materials and applicable disposal fees.

    I don't actually know what the official time is... But $35/hr is cheap :p


    Reply 9 years ago on Introduction

    Yeah I agree. 35 bucks an hour is pretty cheap compared to the rates of other mechanics. I had my water pump and belts replaced and the mechanic charged me $45 an hour. It took him two and a half hours.


    10 years ago on Step 5

    Haha I got in to look at my PS belt because it was squeaking, thought I would just simply tighten it up. When I got in there I found that my tensioner "bolt in question" that you show was completely missing..


    12 years ago

    First, this is an oustanding page. I have a Mazda 626 '96 in which I am removing the head and many of the tasks you mention are ones I am encountering. Your pictures are much clearer than those in my Hanes manual. BTW is 96 4 cyl 626 also a non-inteferece model?

    2 replies