According to my owner’s manual my minivan is due for the timing belt to be replaced. To be truthful, I am passed the recommended time in both years and kilometres. I really need to get it done.
When you are due to replace your timing belt your service provider will often give you some options. Each option will add to the cost of the job.
The options though will be less costly when done with replacing the timing belt because the process of replacing the belt affords easy access to these other components.
In many cases these components require the timing belt to be removed to replace them.
The timing belt is a rubber toothed belt that synchronizes the relationship of your engine’s crankshaft to the camshaft. Ultimately this places the engine pistons in the correct relationship to the intake and exhaust valves to allow the engine to fill with oxygen (breathe).
Failure of this belt (typically the belt teeth tear off) means your engine will stop running immediately. However, many engines (called interference designs) will suffer some catastrophic failure as pistons and valves will collide and result in permanent damage. Expensive damage.
Timing belt replacement usually runs hours rather than minutes. Rubber timing belts do not like oil or coolant getting on them. Both will cause early timing belt failure.
The gears that the timing belt rotates on are usually driven by shafts that require seals to prevent oil from exiting the engine. On some vehicles seal replacement might be a good idea during the timing belt change.
Either the seals have already started to leak or past experience has shown the seals will not last until the timing belt is worn out for the second time.
Seal replacement when the timing belt is already removed may not take a lot of extra time. Seals are usually not expensive components.
The water pump in many engine designs is also driven by the timing belt. A failing water pump will leak engine coolant on the timing belt again resulting in premature failure. Visual inspection or previous experience may make your technician suggest water pump replacement together with the timing belt.
Again this procedure may only add a small amount of time to the timing belt job and again prevent doing the job a second time before the second timing belt is due to be replaced.
Along with the camshaft gear or gears, and the crankshaft gear there will be a timing belt tensioning device as well as one or more idler pulleys that position and guide the belt as required. Many times these components should be replaced during timing belt replacement.
This list may seem long and it is. Last but not least one or more accessory drive belts will be removed in the process of accessing the timing belt. Replacement at this time is only the cost of a new belt.
Many parts manufacturers offer so called timing belt kits that include all the parts that I have written about less the seals. Again these kits represent good value to the customer as opposed to buying all the parts individually.
Altogether this timing belt job adds up to a very significant expenditure.
But if your vehicle gets you breakdown free to the first timing belt replacement at 160 000 kilometres and you are thinking another 160 000 trouble free kilometres is what you desire, your mechanic may be enabling you to do just that.
Trail’s Ron Nutini is a licensed automotive technician and graduate of mechanical engineering from UBC. He will write every other Thursday. E-mail: email@example.com