How To Test For A Broken Timing Belt (Honda 3.0L)

A broken timing belt will cause your 3.0L V-6 Honda (or Acura) to crank but not start. In this tutorial I'm gonna' show you two ways to test your Honda for a broken timing belt.

You can find this tutorial in Spanish here: Verificando Si Está Rota La Correa De Distribución (3.0L Honda Accord y Odyssey) (at: autotecnico-online.com).

Symptoms Of A Broken Timing Belt

The most obvious symptom that the timing belt broke, on your 3.0L V-6 equipped Honda Accord, is that the engine won't start. It'll crank, but no start.

If the engine is running, like when you're driving, and the timing belt breaks, the engine is suddenly gonna' stop and it's not going to restart.

Here are a couple other symptoms:

1. In distributor equipped ignition systems, you won't see any spark created or delivered to the spark plugs, since the distributor rotor will not turn.
2. The fuel injection computer will not pulse (activate) the fuel injectors (if your Honda has the crankshaft position sensors in the distributor).
3. If you were to do an engine compression test, none of the engine cylinders would produce a compression reading on the compression tester.

What Does A Timing Belt Do?

The timing belt serves a very important role in starting your Honda 3.0L V-6 engine and keeping it running. In this section I'll explain in some detail, but without getting too technical, what the timing belt does.

Namely, the timing belt is the belt that controls the camshafts and keeps the intake valves, exhaust valves and pistons synchronized to allow the combustion process to take place (and to keep them from banging into each other).

In a nutshell, this is what happens when you turn the key and crank the engine:

1. The crankshaft (timing gear) drives the timing belt.
2. The timing belt in turn, drives the camshafts on top of the cylinder heads.
   • Your Honda 3.0L V-6 engine has 2 camshafts, one in each cylinder head.
3. The camshafts and the crankshaft are kept synchronized by the timing belt.
4. As the camshafts turn, they activate the intake and exhaust valves
   • The intake valves let fresh air in (to mix with the fuel that will be injected into the cylinder).
   • The exhaust valves let out the exhaust gases from the combustion of fuel and air.
5. The crankshaft activates the pistons and the combustion process begins. In a nutshell, this is what happens (in one cylinder):
   • The piston draws air into the cylinder, since the camshaft has opened the intake valve.
   • The fuel injector injects fuel into the cylinder.
   • The piston starts to compress the air and the fuel since the camshaft has closed the intake valve.
   • The spark plug sparks and ignites the air/fuel mixture, which pushes the piston downward.
   • The piston pushes out the exhaust, which is the end result of the combustion of the fuel and air, since the camshaft has now opened the exhaust valve.
6. Since this process happens in all six cylinders, thanks to the timing belt, the engine starts and stays running.

The timing belt is the one that keeps the valves and pistons synchronized to allow all of the above to happen.

Troubleshooting A Broken Timing Belt

Checking to see if the timing belt is busted, and thus the cause of your Honda's no-start condition, involves two basic tests. These 2 are:

1. Check the rotation of the timing belt.
   • The top timing belt covers have a hole that you can use to see the rotation of the cam gear, while a helper cranks the engine.
   • TEST 1: Check Rotation Of The Camshaft Gear.
2. Check the rotation of the distributor rotor (distributor equipped 3.0L V-6).
   • This test involves removing the distributor cap and then checking for the rotation of the distributor rotor while a helper cranks the engine.
   • TEST 2: Check Rotation Of Distributor Rotor (If Equipped).

Let's turn the page and get testing.