What happens if a timing belt breaks
by Corey
in Blog
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 So you are either thinking about having your timing belt replaced, been quoted for a timing belt replacement or worse news your mechanic has told you your timing belt has broken, bad news all round but much worse is the latter of the three, As mechanics on the Sunshine Coast we often are servicing vehicles that will require a timing belt replacement.

 

Image result for timing belt in engine

http://www.gatescatalogue.com.au/

https://www.repco.com.au/en

 

Let's say we service a car at Service Brakes Tyres Sunshine Coast and the car has a timing belt, if we have not seen this vehicle before we have no idea if the timing belt has been replaced previously, now if the vehicle has low kilometres and we know the schedule for replacement then no problem we would just wait for the kilometres or time to be reached and replace at that time, but more often the case is a vehicle will come in for a service with unknown history of timing belt replacement and the owners are unsure also.

The reason we would be unsure if the timing belt has been replaced or when it was replaced is because it is behind plastic covers that protect it from outside interference and to gain access to the belt it  requires removal of covers , belts , pulleys etc so by the time we get to a point where we can visually inspect it basically we would just replace the belt anyway, before we started to replace a timing belt we would check for a replacement date sticker under the bonnet which should be affixed at time of replacement but unfortunately this often does not happen.

The reason vehicles have timing belts is to time the camshaft(s) to the crankshaft, not all vehicles have belts with some having chains or gears that require far less frequent replacement intervals if at all, belts will generally be replaced every 100,000Kms but this can be up to 150,000Kms and as low as 60,000Kms. When the timing belts are replaced it can be done as just a belt only which is to remove the belt and replace without changing pulleys. tensioners, seals etc or replace the belt as a complete kit which would mean replacing every pulley, seal and tensioner associated with the belt, this is generally the recommended way as problems can occur if there is a pulley or tensioner failure or a seal leaks oil onto the new belt.

Should the timing belt happen to break the top part of the engine including the camshaft(s) and valves will stop turning and no longer be able to move and will stop in whatever position they happen to be, so the valves that are in the top position against the cylinder head are fine but some of the valves will be stuck in the open position, the pistons however will still be moving either through momentum from the wheels if the vehicle is in motion at the time of the break or through winding the motor over to attempt starting the vehicle, the moving pistons will make contact with the stationary valves which are easily damaged and bending of the valves will occur.

Image result for timing belt broken

 There is a version where the valves and pistons will not clash as the engine will be a non- interference fit engine and this means there is enough distance between the fully extended valve and the piston where there will be no contact, if this is the case and the timing belt is broken consider yourself very lucky as a new timing belt will have the vehicle running with no damage taking place.

Should you be unlucky enough to have broken a timing belt and damage has occured the only solution (other than replacing the entire engine) is to have the cylinder head removed and repaired, you can expect the cost to be probably at least two thousand dollars and could be a lot more, considering the price to replace the belt can be as low as $500 it is really a good option to ensure the belt is in good condition.

Service Brakes Tyres Sunshine Coast recommend Gates timing belts.

 

 

 

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