Citroen C3 1.4 Cambelt / Timing Belt Failure

Citroen C3 1.4 8 Valve timing belt failure tensioner failure
The RAC had been to look at this car after the owner reported a non start, they diagnosed snapped cam belt.
RP Services were called out we found the belt intact so tried to turn the engine by hand using a socket and ratchet, this method negates the possibility of damaging valves as you can feel any resistance through the ratchet. We found the crank would turn but it did not drive the belt which means the camshaft was not turning in relation to the crank.


The owner said that she had tried to start the engine for some time before calling the RAC, I explained that these engines are classed as interference type whereby if the timing between crankshaft and camshaft is incorrect there will be a very high risk of valve and/or piston damage.

It was agreed that we would change the timing belt, water pump belt tensioner and serpentine belt, we did this and the vehicle fired into life. There had been no internal damage caused, the owner was very happy and was advised to pick some lottery numbers as the chances of getting away with this type of failure on a Citroen Peugeot TU3 engine are rare indeed.

A couple of points to note the vehicle is 11 years old and it is not known if the timing belt had ever been replaced also the last time the car had been serviced was 4 years previous, when the belt tensioner had been removed it was found to be partially seized, this would have been making a noise for some time and may have been picked up during routine maintenance.

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Renault Scenic dephaser pulley failure

Renault Renault Scenic dephaser pulley failure
Damage caused by seized dephaser pulley on a Renault Scenic Megane f4r
These photographs show the damage of the valves and pistons in a f4r 464 Renault engine due to failure of the dephaser unit.

This is becoming more regular as some garages and mechanics do not know how to check this item correctly.

It is very important that the pulley is checked for excessive play when carrying out cam belt replacement.

If your Renault Scenic Megane or Renault engine fitted with variable timing has a top end rattle it is advisable that you get it checked by a reputable mechanic or garage.

mobile car mechanic kent

Cylinder head and valve damage



This engine had to be replaced due to the catastrophic damage caused.

Cam belt failure Renault Scenic Megane

Cylinder block and piston damage


The role of this pulley is to allow variable timing adjustment it works using a hydraulic system with oil pressure being supplied by the engines oil pump via a valve in the cylinder head.
On later models the valve is electronically monitored.

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