Why are we scared of cambelts?

11 October 2017

Why are we scared of cambelts?

SBF timing belt

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In the ongoing quest to save the pennies and keep costs down, there is one particular stigma attached to buying a used car that can make the difference between deal or no deal. That’s right, the cambelt; something that’s seen as expensive to replace, even more expensive if you don’t. And the longer you keep the vehicle, the greater the chance that you have to do it twice.

Cambelt replacement is one of the most common and costly maintenance jobs for a vehicle; it does need to be budgeted for and the cost to replace one can be the lever that pushes someone to sell up and upgrade their car. This then poses a problem for the buyer who has to factor this into their offer price, and have a looming maintenance cost in the back of their mind.

Cambelts, or timing belts, are made out of rubber and high tensile fibre, so they’re usually quieter than cars that are chain driven. Typically they’ll need to be replaced at intervals based on time or kilometres travelled – a range that usually spans between 60,000 and 100,000kms. The requirements vary from vehicle type, and can even vary from import to domestic models, so the manufacturer’s specifications should be taken into consideration. Most systems will also include other components that may need to be periodically replaced, such as the idler bearings, tensioner, oil seals, and water pump.

Why can the costs of replacement be so high?

At its very simplest, an older Toyota Hilux cambelt was one of the cheapest to replace. The belt cover unclips, the belt and tensioner are replaced and the timing set, the vehicle is reassembled, tested and you’re away. The belt area is not complex, and with few parts to replace, you would have been looking at a cost that hovered around the $200 mark.
On the other hand, a complex engine with a belt running multiple camshafts, idler and tensioner bearings, and water and oil pumps might take a good 3-8 hours to replace and cost $1500. The time needed to even access the belt can be high, cooling systems need to be drained, and in some cases even the radiator requires removal. Limited access to the engine might mean that other significant parts of the vehicle such as mounts, bumpers and lights may also need to be removed.

Why not replace just the belt?

The most thorough way to replace a cambelt is to replace all the relevant components at the same time and, since the engine needs to be completely stripped during replacement, this is the perfect opportunity.
While the mechanic is pulling the front of the engine apart they will probably recommend replacing the water pump and coolant at the same. Depending on the age and mileage of the vehicle, the possibility of the water pump failing not long afterwards can be high. As this is usually a labour-intensive job, replacing both while you have the engine pulled down is the smart thing to do. The only additional cost you’re really incurring is the price of the water pump, which is preferable to paying for the labour twice, should it fail. This also goes for oil seals, and bearings located in the same area. You don’t want to discover an oil leak from behind the timing cover a few months down the line. Worse still, if a bearing seizes and the belts snaps, you could be looking at purchasing a new engine.

The alternative

The timing chain is the crowd favourite as they have no real expiry or replacement interval; however they are not totally free from trouble. If they stretch, wear, or break, the catastrophic engine failure result can be the same, or at a minimum cost a few thousand to replace.

1 comment


15 November 2017 | By john46

Yes, it is important and its a pity the AA pre sales check technician didn't do his job correctly and check mine before I purchased my car.

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