Hardlymoving writes about do-it-yourself automobile maintenance on various makes and models.
Engines: Toyota MZFE
The Toyota MZFE engine is a transversely-mounted, timing-belt driven, 24-valve, dual overhead cam (DOHC) aluminum V6 design. It is used in many Toyota and Lexus cars from 1994 to 2003, including the Lexus ES300 and RX300 and the Toyota Camry, Avalon, and Solara. It comes in a 3.0 liter version, the 1MZFE, and a 3.3 liter version, the 3MZFE. Most engine components in the 1MZFE are interchangeable with the 3MZFE, including the timing belt, tensioner pulley, and guide pulley, although the 3MZFE has a different tensioner configuration.
See my other article for replacement of a timing belt on the four-cylinder Camry (the 5SFE engine).
If you noticed oil leakage from the firewall side valve cover gasket, I have another article on how to replace the gasket on this engine in an Lexus ES300, which uses the same engine.
Replacing Broken Belts
In models before the 1999-2003 introduction of VVTI (Variable Valve Timing) technology, the engine's valve train is “non-interference,” meaning that if the timing belt breaks while the vehicle is operating, it will not necessarily damage the valves or pistons. Therefore, you can use the instructions below to replace a broken timing belt on a non-VVTI engine.
Positioning the camshaft sprockets and the crankshaft pulley alignment marks to Top Dead Center (TDC) is all you need to do before installing the new belt. After installing the belt, you can do a compression leakage test to make sure the valves are still okay.
When to Replace the Timing Belt and Related Parts
Toyota recommends belt replacement after 90,000 miles.
Other parts are often replaced at the same time. Some shops always replace the water pump with the belt, but in my experience, the Aisin water pumps that come with the MZFE Camry are good for at least 200,000 miles.
At 150,000 miles, some guide pulleys (idler pulleys) and tensioner pulleys look worn and need replacement. The tensioner (actuator) doesn't generally need replacing. After 200,000 miles, I would definitely replace the seals (camshaft, crankshaft, and oil pump) and the water pump as well, along with the timing belt. Whether or not you need to replace the seals depends on their mileage, age, and their observed condition after you remove the timing belt cover.
On the four-cylinder 5SFE Camry, these seals do start to leak at about 150K, but on the V6 MZFE, they last longer. Using a "high mileage" oil may swell the seals and stop leakage for a while, though eventually (certainly after ten years) seals turn brittle and this trick won't work.
Allow three or more hours to replace the belt alone.
Reminder: marking the old belt with paint where it meets the crankshaft and camshaft pulleys and transferring these marks to the new belt will make it much easier to install the belt if any of the pulleys happen to move between the removal of the old belt and the installation of the new one.
1MZFE Timing Belt Components
- Impact driver (electric, compressed air, or mechanical)
- High mass impact socket like this one (if encountering difficultly removing the crankshaft pulley bolt with a powered impact driver).
- 1/2" breaker bar (if no impact driver available)
- 1/2" & 3/8" drive socket wrenches
- Metric box wrenches and sockets
- 1/2" & 3/8" wrench extensions
- Screw drivers
- Pulley removal tool like this one (if encountering difficultly removing the crankshaft pulley).
- Toyota camshaft seal installation tool like this one (if replacing seals)
- Camshaft or crankshaft seal removal tool like this one (if replacing seals)
- Long chain strap wrench tool like this one (if removing the camshaft sprocket to replace the camshaft seal)
- Jack (hydraulic or scissor)
- Standard jack stands
Note About Tools
Japanese cars use the following metric sizes: 10mm, 12mm, 14mm, 17mm, 19mm, 21mm, 22mm.
At a minimum, to remove and torque screws and bolts, especially the crankshaft bolt discussed below, you will want a breaker bar. This is a tool of many uses.
The next step up is an impact driver. You can get a manual impact driver, but an electric impact driver is even better, if you can afford it. The one below is the best I have used.
- Replacement timing belt
- Belt tensioner idler pulley (optional)
- Belt guide idler pulley (optional)
- Timing belt cover gasket (optional)
- Side motor mount (engine control rod, "dog bone") (optional)
- Water pump with gasket (optional)
- Power steering fluid (optional)
- Crankshaft and camshaft seals if leaking oil
Common Timing Belt Kit Components (1MZFE)
The cost of the belt and components can vary greatly. If you want to use Japanese OEM (Original Equipment Manufacturer) parts--the parts that Toyota puts its own label on--you will want a Mitsuboshi timing belt, Koyo pulleys, and an Aisin water pump. Other Japanese OEM brands include Denso, NGK, KYB, Akebono, GMB, and Sumoto. Shop and compare prices, including shipping costs, for the best deals.
But you can find good parts from other manufacturers as well. As Japanese cars shift their manufacturing to the US, OEM manufactureres have come to include American companies like Gates and Dayco.
Basically, any Fortune 1000 parts company should provide adequate parts.
1MZFE Timing Belt Kit
3MZFE Timing Belt Kit w/Cam and Crank Seals
Video: Timing Belt & Water Pump Replacement on the Lexus ES300 (1MZFE)
This video, the first stage of my "redo" or makeover project on a Lexus ES300 (3rd Generation), will show you, step-by-step, how to replace the timing belt, water pump, idler pulley, tensioner pulley, cam and crank seals. On this car, which has over 160K miles, the timing belt has slipped, the water pump and pulleys have seized, and many parts are either worn out or in need of replacement. The steps in this video will work on other cars with the V6 1MZFE engine, such as the Camry V6, Solara V6, Highlander V6, Sienna, Avalon, and Lexus RX300.
The 1MZFE engine, of course, is a non-VVTI engine, so a broken timing belt can be replaced with a new belt without any concern that the broken belt has bent the valves.
The video contains the procedures described in the text below, though it has some of the steps in a different order. The video gives more detail than is in the text about replacing the water pump, crankshaft seal, and cam seals.
Video: Timing Belt & Water Pump Replacement on the Toyota Sienna (3MZFE)
This timing belt replacement video is basically the same as the ES300 1MZFE engine but for the Sienna's 3.3L 3MZFE engine. The major difference is the redesign of the belt tensioner pulley bracket.
Video: Timing Belt & Water Pump Replacement on the Toyota Camry (3MZFE)
This timing belt replacement video is for a Camry with the 3MZFE engine. Again, the major difference is the redesign of the belt tensioner pulley bracket.
Step by Step: Replacing the Timing Belt and Other Parts
The instructions and pictures below show how to:
- Remove the accessory belts and crankshaft pulley
- Drain the power steering fluid (optional)
- Remove the timing belt cover and side engine mount
- Replace water pump and pulleys (optional)
- Install the new timing belt
- Put everything back together
Removing the Crankshaft Pulley and Accessory Belts
Letters refer to photos at the end of this section. Click on a photo to enlarge it.
- Place transmission in "park," apply the parking brake, and chock the rear wheels.
- Support the vehicle on a jack stand and remove the passenger-side front wheel.
- Unbolt the front fender apron seal on the passenger side (A).
- Loosen the crankshaft pulley bolt (B). If you don't have an impact driver, use a breaker bar (C) secured to the ground or frame of the car (D). "Thump" the ignition (run it briefly) for around one second. The torque from the starter motor should relieve the tension on the bolt. If that desn't work, it's possible your car's battery is too weak to provide enough amps to loosen the bolt; you can try jumping the battery with another car’s battery. If that doesn't work, applying heat to the bolt from a propane torch can help ... but be careful ... too much heat will damage the oil seal. As a last resort, find a friendly garage owner who'll torque the bolt off for you with their 180-lb air-powered impact driver.
- Turn the engine clockwise (E) to align the crankshaft pulley to the Top-Dead-Center (TDC) mark on the timing belt cover (F). (See video at about 3:45.) Use a 1/2" drive socket wrench attached to the (loosened) pulley bolt to ease engine rotation. Use an impact driver, or do a quick twist of the socket wrench counter-clockwise, to spin off the crankshaft pulley without upsetting the alignment.
- (Optional:) If your power steering fluid has turned black, it's convenient to replace it as part of this job; you can drain it from the power steering pump hose, instead of from the reservoir. Remove the hose clamp and hose from the metal tube located below the crankshaft pulley (G). You can "push" out most of the fluid by turning the steering wheel left and right while the fluid is draining out. When completely drained, reconnect the hose and clamp (H).
- Relieve tension on the alternator pivot bolt (I).
- Loosen the tension on the alternator adjustment locking bolt (J).
- Turn the alternator belt adjustment bolt counter-clockwise until the alternator belt can be removed by pushing down on the alternator.
- Loosen or remove the power steering pump bracket bolt (K,L).
- With either a long metal bar or crowbar, apply pressure to the left side of the pump to relieve tension on the power steering belt (M). Alternatively, a few light taps with a hammer on the power steering pump bracket will move the pump forward of the bolt and relieve tension on the belt.
- Remove both the alternator and power steering pump belts.
- Remove the crankshaft pulley bolt (N) and remove the pulley (see video at 4:40.) If the pulley does not slide out with a simple tug, a pulley removal tool may be required (O).
Removing the Crankshaft Pulley and Accessory Belts: Photos A-O
Removing the Side Engine Mount and Timing Belt Cover
Letters refer to photos at the end of this section. Click on a photo to enlarge it.
- Disconnect the coolant reservoir hose from the reservoir container (P).
- Disconnect the two engine ground wire connectors (Q).
- Unbolt and remove the side engine mount (R, S).
- Remove the alternator bracket nut and bracket (T).
- Optional: to give yourself more room to work, you can detach the power steering hose and move it to the firewall (U, V).
- Unbolt and remove the lower timing belt cover, the upper timing belt cover, and the side engine mount bracket. Keep the one long bolt in place while removing the bracket (W).
- Remove the timing belt guide (X, Y, Z, AA, BB).
Removing the Side Engine Mount and Timing Belt Cover: Photos P-BB
Removing the Timing Belt
Letters refer to photos at the end of this section. Click on a photo to enlarge it.
- Check that the camshaft alignment marks match the backing plate alignment marks. If not aligned, screw the crankshaft bolt back in and rotate the engine with a wrench until alignment is made (CC).
- After the engine is aligned, apply paint marks to the camshafts and crankshaft, to their backing plates, and to the timing belt. These marks will help with re-alignment if the crankshaft or camshafts happen to move during belt installation (DD).
- Unbolt the timing belt tensioner (EE). *NOTE: For the 3MZFE engine (i.e. the 3.3 liter V6), the belt tensioner has been redesigned and the lower right motor mount has been added by Toyota blocking removal of the tensioner. To remove the 3MZFE belt tensioner, the right lower engine mount must first be removed followed by the engine mount bracket. To do this: 1. Remove the front motor mount bolt. 2. Remove the lower right motor mount upper and lower nuts. 3. Place a hydraulic jack with wood block under the engine oil pan and slowly tilt the engine up until there is enough clearance to removed the right motor mount. 4. After the mount has been removed, unbolt the mount bracket which will allow access to the belt tensioner bolts for removal.
- Twist the timing belt about 45 degrees, simultaneously, in two places: between the right camshaft and the crankshaft, and between and the right camshaft and left camshaft. This will slightly move both camshafts clockwise, which makes it easier to remove the old belt, as well as easier to install the new belt. A small amount of slack will now exist between both camshafts and between the right camshaft and the crankshaft.
- Remove the old timing belt (FF).
- Transfer the paint marks from the old belt to the new belt: set the old belt down, place the new belt over the old belt with their cogs aligned, and wherever you see a mark on the old belt, place a matching mark on the new one.
Removing the Timing Belt: Photos CC-FF
Optional: Replacing the Water Pump, Guide Pulley, and Tensioner Pulley
If you want to replace the water pump as part of this job, a 10mm stud removal tool or an "E" socket will make it much easier. This tool or socket will ease removal of the pump's mounting stud, thereby allowing the pump to clear the camshaft-side timing belt cover. Removing the stud is easier than removing the camshaft sprockets and belt cover before removing the pump. Use a wire brush (see video at 13:50) to remove any residual corrosion before installing the new gasket (I use a round brush mounted on a angled drill). Denso water pumps come with a metal gasket with a rubber coated inside lip which does not require any RTV.
If you purchased a timing belt component kit, your kit should include a new guide pulley or idler pulley (the pulley between the two camshaft sprockets) and a new tensioner pulley (between the crankshaft and left camshaft). The guide pulley can be easily replaced by unbolting the old and bolting on the new. The tensioner pulley is slightly more difficult. This pulley is part of an assembly that allows the pulley to dynamically apply continuous pressure on the timing belt (via the tensioner) to take up the slack if the belt stretches. The tensioner mounting bolt runs through a sleeve that allows the pulley to move approximately 30 degrees to take up belt slack.
Installing the New Timing Belt: Reassembly
Letters refer to photos at the end of this section. Click on a photo to enlarge it. See also the video at 24:00 and following.
- Start by installing the new belt on the right camshaft using the paint line on the new belt (GG). Prevent the belt from slipping off by using a spring loaded plastic alligator clip (HH).
- Stretch the belt and slip the belt onto the left camshaft. Again, use the paint line on the new belt for alignment and use a plastic alligator clip to prevent the belt from slipping off.
- Guide the right side of the belt over the water pump and then position the belt on the crankshaft pulley cogs. There should be little to no slack when this is done. Slack may be a sign that the belt is loose by one cog.
- While holding the belt in place over the crankshaft pulley with the right hand, use the left hand to slip the left side of the belt over the tensioner pulley (II).
- Bolt on the timing belt tensioner. Applying alternating equal turns on each bolt will gradually compress the tensioner pin against the tensioner pulley assembly. As this occurs, the timing belt will tighten up.
- (Optional:) At this point you can start the car to check the belt alignment. If the car misfires, or the "Check Engine" light comes on, turn off the car, connect the crankshaft pulley bolt, and rotate the engine with a ratchet wrench to the alignment marks. Being off by one cog will cause an engine misfire. If this happens, the problem is usually between the right camshaft and the crankshaft.
- Reverse the outlined instructions to reconnect removed components (JJ). The crankshaft pulley bolt can be 'shocked' (torqued) on with a mechanical impact driver, if either an air or electrically powered impact driver is not available (you may be able to rent them at an auto retailer). Alternatively, you can always bring your car to a private garage and ask them to torque the bolt on for you. Usually they'll do it for free out of professional courtesy.
- If the power steering fluid was drained, pour in new fluid and turn the steering wheel right to left to create suction. The fluid level should drop. Add more fluid and repeat the procedure until the fluid level has stabilized.
Installing the New Timing Belt: Reassembly (GG-JJ)
Fixing an Oil Leak Not From the Timing Belt Area
If when you replace the firewall-side camshaft oil seal you notice oil leakage from the valve cover gasket—which is not that uncommon in high-mileage cars—you can go to my other article on how to replace the valve cover gaskets on a Lexus ES300, which has the same engine and layout as your six-cylinder Camry.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
Questions & Answers
Question: I have Sienna 2006 3.3l, and it has a VVT-i engine. I was driving 70 miles/hour and the timing belt broke. What is the chance that the valves are bent?
Answer: Tough question. I'll guess 50/50 that they may be okay. What I would do is replace the time belt, start the car up and see how it runs. Otherwise, you'll have to do a compression check on each cylinder which in itself is time consuming. After putting on the new belt, you can start the car without having to put everything back on (i.e. crankshaft pulley, covers, motor mounts, belts, etc.)
Question: I have a 2006 sienna 3.3 l, and it just didn’t start one morning. The tensioner/ tensioner pulley failed. I replaced the whole timing kit, but before I put the belt on, I safely lined up the camshaft marks and the crankshaft mark without causing damage. Any advice?
Answer: You can try, but the 3.3 3MZ-FE is an interference engine. While getting the crankshaft to TDC, you have to gradually move the camshafts aligned with the pistons.
Question: Do the arrows on timing belt point toward the engine or the mechanic?
Answer: The engine.
Question: My dad has a 2002 Toyota Avalon XL with the 1MZ-FE engine. I have already replaced the rear valve cover gasket as I notice oil leaking. However, after changing the rear valve cover, I still see some oil sipping down from the corner of the valve cover right below the timing cover on the rear passenger side. Could it be coming from the rear cam seal? Is it possible to remove the #2 timing cover without removing #1 cover and/or the side mounting bracket?
Answer: Yes, more than likely it's the rear cam seal. The lower cover mounts over the top cover so you have to remove the lower before taking off the top. It's a timing belt job.
Question: Do you have similar detailed instructions to remove an axle from a Toyota Camry with a 3.0L 1MZ-FE Engine?
Answer: If you're dealing with the driver's side, you can use the Toyota Camry 2.2L 5SFE instructions, but I don't have one yet for the passenger side.