Wednesday, 23 March 2016

Excessive mechanical noise and lack of power in Renault petrol engines

Detail of the variable valve timing system
This fault affects models of the Renault group that have the following cylinder capacities and engine codes:

1.4 16V - K4J
1.6 16V - K4M
2.0 16V - F4R

*Only in engines equipped with a variable valve timing system.


With the engine running, excessive mechanical noise is heard from the top of the engine, specifically on the camshaft side on the timing side. The system displays different symptoms in the event of this fault:

- Fault indicator light on
- Excessive noise
- Unstable idling
- Lack of response
- Engine shaking or jerking
- Lack of power
- Engine rattles or is noisy
- Exhaust smells

When reading the fault codes using the diagnostic machine, the related codes are as follows:

Check No 1

To describe the checks to carry out on the system components, we will use the information contained on platform (information system for the diagnostic) to help us.

Firstly, the variable valve timing solenoid valve should be checked as it controls the variable valve timing.

This check is carried out in order to discover a possible electrical fault.

For the check, the oscilloscope will be used as shown in the following image:

Solenoid activation check (information extracted from

If the solenoid valve is operating correctly, go to check number 2.

Check No 2:

This check involves reading the engine position sensors, i.e., the synchronisation between the camshaft and crankshaft.

For the measurement, the oscilloscope shall be used and connected as shown in the following image:

Checking the camshaft sensor (information extracted from

Next, check the engine RPM and TDC sensor.

For the measurement, the oscilloscope shall be used and connected as shown in the following image:

RPM sensor check (information extracted from

Once both sensors are checked, the synchronisation between them has to be known. This is done in the following way, with use of the oscilloscope and connecting a cable to the camshaft sensor signal cable (CH1 -> F1), another to the RPM and TDC sensor signal cable (CH2 -> E4) and the oscilloscope common to earth.

The sensor signals should not show synchronisation oscillations between them at constant speed. If variations are observed, the fault will be mechanical.

The image shows the synchronisation of both sensors


Variable valve timing system drum

The mechanical fault may be due to a loss of tension of the timing belt or a problem in one of the timing components but, in the majority of cases, the problem is related to the variable valve timing system drum.

This is because the materials used in the manufacture of the drum cannot withstand the operating loads and internal leakage occurs preventing it from being regulated correctly. The solution is to replace the component.

Depending on the problems that have arisen, the maker has launched various modifications to the component and has now reached the third series, which, in theory, has solved the mechanical fault of the affected engines.

Below are the reference numbers of the spare part, according to the series:

First series: 7701474362
Second series: 7701478079
Third series: 7701478505

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