(Updated on December 20, 2022)
Many vehicles using timing belts to keep the valves and crankshaft aligned. This alignment allows the engine to make the most of each combustion event.
If you have experience wrenching in the garage, a timing belt replacement can be a great next step to advance your home mechanic skills.
If you are new to engine maintenance, there are some things you will want to keep in mind to make sure the work goes smoothly, and you only have to do it once.
Tips for Replacing a Timing Belt
1) Do Your Research
Before you dive into any major repair work, it’s a great idea to do as much research as you can. What common pitfalls have other owners experienced? What parts will you need? Have any owners discovered tricks to make the job significantly easier?
Do you have an interference or non-interference engine? The stakes are lower on a non-interference engine, because it is impossible to experience valve-to-valve or piston-to-valve contact, even if the engine timing is way off.
Make sure the parts you buy are the correct part numbers for your specific VIN. Many models come with several different engine options. The parts can look very similar and are not always compatible between trim options.
Some engines require cylinder 1 to be at top dead center (TDC). Others require the pistons to be at their midpoint of travel (many Subaru engines work this way). Many engines don’t even have timing belts anymore.
Make sure you research the correct configuration for your specific timing belt replacement. You’ll also need to know the correct order of operations for installing the belt, taking up slack, and applying the timing belt tensioner.
Every engine manufacturer uses a slightly different implementation for these things, so it’s good to know the nuances of your specific engine before diving into the job for the first time.
2) Buy a Factory Service Manual
A factory service manual (FSM) is a book full of every system and specification in a given year, make, and model of vehicle. The target audience is primarily service technicians and general mechanics.
Factory service manuals contain everything from wiring diagrams to troubleshooting steps for common issues. They also contain torque specs for every fastener on the vehicle.
Haynes and Chilton repair manuals are fantastic to have on hand, as they are both inexpensive and easy to read. However, nothing quite beats the OEM manual for level of detail about how different systems interact.
Factory service manuals also tend to have the best exploded-view diagrams of different systems (also called blow out diagrams).
3) Grab a Torque Wrench
Torque wrenches allow you to measure the tightening force you apply to a fastener. When working on engines, it’s critical to reference the manufacturer’s torque specifications for each fastener. Most modern engines are built out of aluminum. It is much easier to strip the threads on aluminum components than iron or steel.
Make sure you reference the factory service manual to get all of your torque specs as you put the engine back together. If a bolt is not tight enough, it could back out over the course of thousands of miles due to engine vibrations.
If a bolt is too tight, it could stretch (also called “yield”), warp the components it holds together, or strip threads. While most stripped threads are repairable, this will add significant time to the job. Stripped threads are commonly repaired using a Heli-Coil or Time-Sert kit.
4) Turn the Engine By Hand
After you’ve installed your new timing belt, turn the engine over by hand a few times. Make sure the engine turns over easily. If the engine binds or becomes really difficult to move, check your work.
When you turn your engine, make sure you’re turning it in the direction the crankshaft is meant to rotate. This is typically clockwise, but check the factory service manual to know for sure.
Spinning the engine backwards isn’t good for it, and could potentially mess up your timing if you haven’t installed the timing belt tensioner yet.
See Also: Timing Belt vs Serpentine Belt
5) Double Check Your Timing
It’s not fun to throw an engine back together only to have it idle poorly because the timing is off. After you’ve turned the engine over by hand a few times, recheck your timing marks. The marks should be in the exact same location when you return to your original alignment configuration.
6) “While I’m In There” Maintenance
Most timing belts require a decent amount of engine teardown. After going through all that effort, there may be several other components that can be very easily replaced if they are starting to age.
Some common examples of components you might want to replace while you’re in there are the front main seal, camshaft seals, valve cover gasket, idler pulleys, timing belt tensioner, thermostat, miscellaneous cooling hoses, and the water pump.
7) Have a Backup Vehicle
In case something goes sideways, it’s always good to arrange backup transportation while your vehicle is in the garage. A timing belt job can take as little as an hour for an experienced mechanic.
Chances are good that this job will take you at least the weekend if it’s your first time. Sometimes you have to order additional parts which can set back your timeline as well.
If you can change your brakes, you can probably change your own timing belt. This is a great way to learn more about your engine and how to work on cars in general.
If in doubt, search for information on YouTube or forums for your specific vehicle. Other vehicle owners who have done the job are likely to have great tips to help get you started.