Common issues and fixes for Renault K4M Engine as fitted to the Modus/ Clio/ Megane and more
We have been running a 2005 Renault modus 1.6l Automatic for the last 8 yrs and this is an overview of some of the common issues encountered and fixes. All are very achievable to address for the home mechanic with basic tools. Other than the below it has proven an easy car to live with. Tax and fuel economy are not great for a car of it’s size but purchase price is low. It’s a practical vehicle for the size.
The engine model is the Renault K4m 1.6 VVT. This fairly trusty Renault stalwart was used in a wide range for Renault cars including the Megane, Clio and Modus so this information may also prove relevant for these cars with some subtle difference.
Note: This is my experience as a home DIY mechanic and no substitute for proper mechanical advice. This is a 10+ yr old French hatchback with a low re-sale value so am not bothered about the risk of breaking something. However all the below has worked for me and we have had a solid 8yrs of motoring applying these fixes, with zero AA/RAC callouts to date.
The Modus itself is a bit of a pain to work on from a space perspective. Not entirely unexpected given the space the engine is shoe horned into but worth bearing in mind. Its not the most comfortable car to work on.
These are the issues covered on this post with the fix identified (click links to jump to fix):
- Rough running – Ignition coil failure, camshaft sensor
- Warm/hot starting and stalling – Dirty Throttle body or Crankshaft sensor
- Oil in water/ Oil leaks – Warped thermostat/ bad thermostat seal
- Clattering noise on startup – Cam de-phaser pully
- The dreaded headlight replacement – Dismantling the front end to change a bulb
Ignition coil failure – Cost of self fix – ~£12-£80 – Time 15mins
Tools required: t20 torx driver, 10mm socket on ratchet. (I use a Bahco ¼” socket set)
Parts required: 1-4 New ignition coils.
Symptom – Rough running, lack of power, Spanner engine management light illuminated on the dashboard.
Common to most modern cars each cylinder has it’s own ignition coil which is positioned on the spark plug. Older cars would use a single coil with High tension (the thick high voltage lines) to each spark plug. This is any easy swap with minimal effort.
Procedure:
1. Remove the Plastic grille and scuttle that cover access to the engine under the bonnet (hood). The first requires removing 4 t20 screws. The second 6 10mm bolts.
2. This will reveal the 4 ignition coil modules. To remove each you will need to unclip the cable first.
3. Remove the 10mm bolt holding it down
4. Lift off from the spark plug, a straight pull.
If you are not using a code reading tool to know which coil is problematic, and trying to get away with replacing only one, you will likely have to pull each one and replace in turn, running the engine to see if fixed, until you work out the problem coil.
5. Re-assemble in reverse.
camshaft sensor replacement
Tools required: t20 torx driver, 10mm socket on ratchet. (I use a Bahco ¼” socket set), 10mm ring/ open ended spanner, small flat blade screwdriver
Parts required: New camshaft sensor (Around £15+)
Symptom – In my experience primarily “check emissions” spanner engine management light illuminated on the dashboard.
This is a fairly easy change although removing the sensor fastening bolt can be slightly fiddly.
- Follow steps 1, 2 as for ignition coil change. In this case to gain access to the sensor you need to remove the 4th coil.
- Once removed you can see the 10mm bolt holding the sensor in place. This is best loosened with a 10mm spanner before removing with fingers. Slightly fiddly.
- Pop the electrical connector off the sensor. I find this is easiest with a flat blade screwdriver from the coil end to flip the clip and push the connector off.
- Pull out the sensor and remove. It has a silicone rubber O-ring seal so you may need to lever gently with the screwdriver.
- Reassemble in reverse.
Stalling and failure to start when warm or hot
This has a couple of potential common causes. A warm start issue where the car starts fine cold can be an electrical or fueling issue. In our case this issue started intermittently, with the symptoms a failure to start, or stall at idle, after a short journey, sometimes starting after a few goes and turning over fine. But absolutely no issues starting cold. After a few weeks it became totally impossible to start warm, taking at least 1hr to cool down before starting.
This fix was a bit of a journey of exploration with the following all completed.
– Air filter change
– Throttle body clean
– Cam Sensor Replacement
– Crank sensor replacement. Bingo.
My initial thought process was focused on fueling, as my mechanical experience has tended to be on older carburated cars however in this case the crank sensor proved to be the fix needed.
Dirty Throttle body – Cost of self fix – ~£0.50 – Time 45mins
Tools required: t20 torx driver, 10mm socket on ratchet. (I use a Bahco ¼” socket set), flat bladed screwdriver, toothbrush
Parts: Carb cleaner or other engine grime removal spray, fluid.
This task was suprisingly straightforward given the cramped nature of the Modus Engine bay. The key difference with some other applications of this engine is that the throttle body is mounted to the rear right side of the engine so accessible with minimal removal of other parts necessary. I tried this fix to solve my hot start and stalling issues as a gunky throttle body had previously caused me stalling issues on another vehicle (Volvo V50 1.8 Petrol).
1. Remove the Plastic grille and scuttle that cover access to the engine under the bonnet (hood). The first requires removing 4 t20 screws. The second 6 10mm bolts.
2. Disconnect the end of the large air hose from the filter box that connects to the throttle body. This can be tucked to the back of the engine out of the way.
3. Unclip the electrical connector to the throttle body. These are sometimes a bit fiddly.
4. Unbolt the 4 10mm bolts that hold the throttle body to the inlet manifold and remove the throttle body. The throttle body can be cleaned in-situ using throttle body cleaner and a toothbrush however you will never clean as thoroughly without removal as you can’t as easily get behind the throttle plate. I find engine degreaser or white spirit just as effective as spray to remove the gunk tbh.
5. Reassemble in reverse. Note: Over time the ECU may adapt to reduced air flow in a gunky induction system. Once cleaned it may take a few miles of running for the ECU to relearn the appropriate engine settings.
CRANK SENSOR REPLACEMENT
Tools required: t20 torx driver, 10mm socket on ratchet. (I use a Bahco ¼” socket set), flat bladed screwdriver
Parts: New crank sensor – I bought a Dephi one for £23 inc. Postage
In my case this turned out to be the issue. The sensor is a critical component as without functioning the engine will not fire at all. The fix itself is actually pretty straightforward, however finding the crank sensor proved to be significantly more difficult. There are a range of forum posts on this topic and it appears the main issue is likely a difference in positioning on the automatic, which I have, versus the manual. (And possibly some difference in various engine versions). In the manual version
Once located it was simply a matter of unclipping the connector, removing one 10mm bolt and withdrawing the sensor. Initially in order to find the connector I had to remove a fair amount from the engine bay including the air intake up to the throttle body intake hose, battery and plastic battery casing. Pushing aside a piece of wiring loom the sensor is nestled at the rear of the engine down and right of the thermostat housing.
The good news is that once located I discovered you can actually access and swap the sensor from underneath by feel without having to remove any of plastic. See pic below for rough location.
thermostat replacement
Tools required: t20 torx driver, 10mm socket on ratchet. (I use a Bahco ¼” socket set), flat bladed screwdriver, spring hose clip tool, 13mm socket with long extension bar (I use Bahco 1/2″ socket set)
Parts: New thermostat housing, 5l coolant (OAT type).
Symptoms: I have encountered both of the common symptoms of a bad thermostat seal, replacing originally the seal and more recently the whole unit. The first is oil in the coolant (often confused, incorrectly, for rare head gasket issues), the second an oil leak from the thermostat housing. In my case the weeping oil dribbled down onto the drive shaft which, with subsequent spraying, makes a horrible mess.
Whilst this job itself is not so complex the packed in nature of the Modus engine bay renders it a bit of a hassle. To get good access it is necessary to remove the battery box and air filter assembly.
1. Remove the Plastic grille and scuttle that cover access to the engine under the bonnet (hood). The first requires removing 4 t20 screws. The second 6 10mm bolts.
2. Disconnect the end of the large air hose from the filter box that connects to the throttle body. Flat head screwdriver.
3. Remove the battery box cover, 2 plastic pieces, unbolt and remove the battery (Note this will reset the radio so the radio code will be required when reconnecting). Then through unclipping a few plastic clips and a bit of brute force and swearing unclip the battery box surround and remove. This is a bit of a brute to reassemble so take a few photos to note orientation and where everything clips.
4. Remove the air intake hose, to the filter housing. All plastic clips. Remove the filter housing. Once the hoses are out of the way and battery box removed this is straightforward.
5. Drain the coolant. I do this by unclipping the bottom hose on the radiator, from underneath (middle of car at front) and draining to a washing up bowl. It is not worth trying to change the thermostat without draining the coolant, coolant will get simply everywhere.
6. Unclip the 2 hoses connected to the thermostat housing. push these to the side out of the way.
7. Unclip the thermostat itself from the housing. Centre of the housing. This is held in place by a sprung steel clip which can be prised off with a screwdriver. It pushes into an O-ring for a seal.
8. Unbolt all of the bolts holding the thermostat to the engine (10mm bolts). You will find some oil and coolant will dribble out so having a suitable rag to hand is useful. There is one bracket bolted to the rear of the thermostat housing which needs unbolting with a single 10mm bolt.
9. Clean mating face of engine. You will likely see some carbon build up. 1000+ grit wet and dry and some carb cleaner or somesuch should shift it to leave a clean face for the new thermostat to seal with.
10. Attach new thermostat. The suggestion is to lightly bolt (7nm) the new thermostat to the head starting centrally and tightening all bolts in a spiral shape, before torqueing all to 11nm in the same pattern.
11. Re-attach the hoses to the thermostat, and thermostat connector itself. Before re-assembling the battery box and air filter box/ intake hoses I recommended reattaching the battery, refilling the coolant and running the engine, to check the leak is fixed. Far easier to spot a leak and worth the extra step of having to remove the battery again before moving to step 12.
12. Re-assemble the air filter and battery box assemblys in reverse.
13. If you didn’t do this in step 11 refill the coolant and bleed using the bleed screw on the thermostat. It is easiest to add the plastic intake hoses to the air box last in my opinion as they make reaching the bleed screw difficult.
14. Reattach the engine bay covers and scuttle.