HOW TO IMPROVE THE COOLING OF YOUR 4L Car?I quickly brought up the subject during the last article on the preparation of the 4L for Blue Rally Europe : cooling is THE important point to check before leaving for this adventure. If the 4L is naturally prone to overheating, the high temperatures during the raid (30 to 40 ° C !) As well as the unevenness of the roads do not help … The consequences can be significant: rupture of the cylinder head gasket, bursting of the hoses and same engine failure. It is therefore essential to carry out some operations to check and improve the cooling system on your 4L.

BUYING A GOOD QUALITY MATTRESS manufactured these days have a prolonged life.

For those who participate, and in order to put the odds in your favor and limit the risk of overheating as much as possible during the Blue Rally Europe, we will deal with two subjects here:

Preparation of the 4L upstream of the raid to control and improve engine cooling.
Tips to avoid overheating once on the rally.
Obviously, the two points are complementary: do not neglect them!

Before getting to the heart of the matter, if you want to know more about how the cooling works on our dear 4Ls, it’s here !

There are many ways to check the proper functioning of the cooling system of your 4L, or even improve it, and what we are going to see in this part.


Among these operations, some are very strongly recommended or even made compulsory by the organization of the Blue Rally Europe to start (refer to the certificate of mechanical preparation). It is therefore with these steps that we will begin!


1st step: check the general condition of the cooling circuit
The first thing to do is to check that all the elements that make up the cooling system are both functional and in good condition. To go on such a journey, the slightest water leak or damaged cooling piece is not an option and could well spoil the adventure. The raid takes place in the middle of summer and the temperatures, like the 4L, will climb!

Here are the points to check before departure .

Global control of the cooling circuit and leaks
We start by checking that there are no leaks in the cooling circuit. The most common parts that leak are:

The connections of the hose : no clamps, incorrect tightening of the collar, a worn hose or distorted with time are all causes leading to leakage. The large hose at the water pump outlet is particularly prone to leaks.
The radiator : located just behind the radiator grille on engines, it is exposed to shocks and stone throws. Leaks are therefore quite frequent.

The water pump : the gasket between the water pump and the cylinder head may end up hardening and no longer playing its sealing role. It’s a pretty classic leak. If the water pump is damaged (cracked), there is a good chance that it is a source of leakage.

Overall, check that the level of coolant in the expansion tank does not drop. If this is the case, there is bound to be a leak. You will need to find it and fix the problem before you leave.

Bad clamping of clamps is frequent … Check them regularly and tighten them if necessary.
Checking the condition of the cooling hoses
As we have just seen, hoses are the main source of leaks on 4Ls , as on many cars. Made of rubber, they are also relatively fragile and deteriorate over the years.

There are generally 5 of the 4L:

2 heating hoses: those with the smallest diameter and which fit into the passenger compartment up to the heating block.
1 hose connecting the water pump outlet to the radiator inlet.
1 connecting the radiator outlet to the inlet of the water pump.
The very fine hose connecting the expansion tank to the radiator.

So check that the hoses are not:

deformed: even with a clamp, the assembly is no longer waterproof.
Replace them if necessary. There are also complete kits on the market with all silicone hoses : it is an excellent alternative to rubber. Silicone makes them more resistant over time and less sensitive to heat and temperature variations.Silicone hoses are for me an excellent investment if your rubber hoses are tired. 75 € the complete kit for engine.

Visual check of the condition of the radiator
The radiator is a rather fragile part of the engine and subject, as we have seen, to road projections . It is therefore not uncommon to see radiators in very poor condition and whose beam fins are completely sunk. In addition to limiting the role of the radiator (cooling), it can also be synonymous with leaks.

If visually, your radiator seems damaged, first check that it is not leaking.

If it is only very lightly pushed in and has been lightly impacted, it is possible to reshape the fins with a small comb, or carefully with a small screwdriver if you are good with your hands. ;). If it has suffered a severe shock or too many impacts, it is better to replace it.

Checking the overall condition of the water pump
Frequent problems with the water pump are as follows:

Seizure of the mechanism . In this case the pulley of the water pump tends to force when turned by hand, and there are hard spots. It will also squeak. These are the signs that it needs to be replaced!
Pump Crack or Breakage : Being made of aluminum, the water pump is prone to cracks and breakage. In this case again, you have no choice but to change it.The water pumps on the 4L are easy to find, are not very expensive (around € 40) and are easily replaced: do not take the risk of leaving with a dubious water pump!

Do not hesitate to replace your water pump if it shows the slightest sign of fatigue!


Checking the operation of the calorstat
The calorstat is this small part located in the hose at the outlet of the water pump and which will decide, depending on the temperature of the coolant, whether it must circulate in the radiator to be cooled or not.

When it no longer plays its role, the calorstat remains closed and thus no longer allows water to pass, which is no longer cooled. To check it, start your engine and let it idle for a few minutes, while the water can heat up. At the start, you should feel that the temperature of the hose in which the calorstat is located is “cold” on the radiator side and hot on the water pump side. After a few minutes you should notice that the calorstat has opened and that the hose has become very hot, even on the radiator side.

If not, replace the calorstat ! You just have to disconnect the big hose at the water pump outlet: the calorstat is right there. It comes relatively easily by pulling on it with pliers.

A calorstat is worth 3 times nothing and can be replaced in a few minutes.
Checking the operation of the probe and the fan (Cleon motors)
On “small” Billancourt engines, the water pump pulley directly actuates the radiator fan: the latter therefore operates continuously and there is little risk of failure on this side.

On the “big”  engines, on the other hand, it is the sensor located at the bottom right of the radiator which activates the fan at a precise water temperature. To check that they are working properly, let the engine idle for ten minutes (+ or – depending on the outside temperature), the fan should eventually come on.

If this is not the case, it is because your probe is out of order and it will have to be replaced (the electric fan only rarely breaks down).

Here is the fan sensor on the motor : it is located at the bottom of the radiator, just above the lower outlet.
Checking the cylinder head gasket
Rest assured, the goal here is not to have your engine exhausted to check the condition of your cylinder head gasket. In any case, this would lead to the replacement of the latter.

The main objective is to check that the cylinder head gasket is not cracked and that the seal between the oil circuit and the water circuit at the cylinder head is still ensured . If this is not the case, several symptoms may warn you:

Presence of “mayonnaise ” inside the oil filler cap of the rocker cover. It is quite simply the water which has mixed with the oil following a breakage of the cylinder head gasket.
White smoke from the exhaust.

Loss of power .
In these cases, replacing the cylinder head gasket is inevitable . Likewise, if you have noticed that your 4L is heating up abnormally or you are in doubt about the condition of your head gasket, it is best to replace it before leaving for Blue Rally Europe. Prevention is better than cure !

3rd step: cleaning and draining the coolant circuit
Once the cooling circuit has been checked, the next step can be taken: cleaning and draining the cooling liquid circuit. To be effective, this operation must be carried out in 3 phases: cleaning, rinsing / emptying, filling with new liquid.

Cleaning the cooling circuit
This dissolves the sludge and scale that has formed over time, heat and corrosion and thus unclogs all the pipes in the water circuit. This is all the more important since the 4L is particularly prone to these problems: mud often forms around the cylinder liners and prevents the engine from cooling properly.

The expansion tank cap is closed again and the engine is left to idle to warm it up and to circulate the product throughout the circuit.Remember to put the thermostat of your heating in the “hot” position in order to circulate the product throughout the circuit.Allow to warm up until the engine exceeds its optimum operating temperature: approximately 90 ° C.It is best to let the product act until the radiator fan is triggered: in this case we are sure that the calorstat has opened and that the product has circulated in the radiator.
Rinsing and emptying the circuit
Once the product has acted well, the engine is shut off. It will have to be rinsed several times and the circuit completely drained.

We start by opening the cap of the expansion tank …

… Then that of the radiator.

A drip tray is placed below the engine to collect the coolant.

Loosen the hose clamp from the bottom of the radiator and remove it. We also remove the water drain screw located on the distribution side (Cléon) or below the inlet (Billancourt) and open the bleed screw.

All the liquid is allowed to flow into the tank. Once finished, replace the radiator hose and close the drain and bleed screws.

I then use fresh water to rinse the circuit and remove the last traces of the product or deposits.

Pour the water container into the circuit and let the engine run for a few minutes to rinse the circuit.

We drain again. Repeat the operation (minimum 2 times) until the drained water is perfectly clear.

Close the hoses and the drain screw.
Filling with new coolant
Now and only now that my circuit is well cleaned, rinsed and drained, can I fill it with coolant!

I can only recommend that you use a quality coolant and ban “low prices” . In fact, the more upscale liquids are generally loaded with additives allowing them to improve the cooling of the circuit by facilitating their circulation while containing anti-corrosion agents limiting the formation of sludge in particular.

A new can of quality coolant is used.
We start by pouring part of the coolant into the radiator (do not fill it completely for the moment).
Optional: I am using an additive here that is supposed to lower the temperature of the liquid to prevent overheating while protecting my circuit from oxidation.
It must be diluted to 5% in the coolant.
The additive is poured into the radiator and completed with coolant.
We close the radiator cap.
Then slowly fill the expansion tank with coolant (wait for the liquid to flow into the circuit).

It is half full for the moment. The engine is left to run until the radiator fan kicks in to expel any air bubbles and fill the circuit.At the same time, check that the level of the expansion tank is not too low and top up if necessary as and when.The bleed screw is opened and allowed to flow until a continuous flow of liquid without air bubbles flows. We close the bleed screw.

Let cool and top up the expansion tank if necessary. It’s over !
3rd step: assembly of an additional fan controlled by a manual switch (Cleon motor)
As we have seen, the 4L’s cooling system is not the most efficient there is. One of the techniques to improve it is to add a second fan, in addition to the original one for the 4Ls originally fitted with a Cléon engine.

Connected to a manual switch, you can activate it in the event of heating or in anticipation of overheating (traffic jams, steep hills, etc.), which you can control by installing a water temperature manometer.


We can make 3 different assemblies:

2 original fans : we leave the original fan and add an identical one next to it (recovered in breakage, on LBC, etc.).
1 original fan + 1 “SPAL competition” type fan .
2 “SPAL competition” type fans : in this case, the original fan is removed.
Double additional fan 4L Trophy
Mounting of two original fans: the second is placed slightly behind.

Assembly of two SPAL fans.
And no, there is absolutely no point in painting the blades yellow … we will say that at the time I was carefree 🙂
Fan of origin vs fan competition “SPAL”
The fans in the picture below are normally intended for competition and prove to be much more efficient than the original ones. The advantages of these fans are multiple :

the fans are very powerful and are in direct contact with the radiator
their assembly is extremely simple with the Revotec fixing kits.
their size is very small.
The other side of the coin is that they come at a certain cost. So it’s up to you to make your choice!

You can find these parts here:

REVOTEC radiator mounting kit
SPAL 190mm suction fan
We will now see how to proceed for mounting this second fan.

I start by removing the old original fan (only for those who want to install two SPAL type fans).

The original fan of the 4L. It is normally black and placed a little further to the right on the radiator.

The power to the fan is disconnected.

Then I drill the pop rivets that secure the fan to the radiator (top and bottom).

I can remove the original fan.

The radiator is now bare, we will be able to install our 2 competition fans!

How to install an additional fan on his 4L?
Now we will see how to install the 2 SPAL fans . Of course, the procedure is the same if you only want to install one SPAL fan next to the original one. You will then have to choose a model with a small diameter so that it can miss it. For my part, I installed two 190 mm SPALs here.

If you want to install a second “original” fan and not a SPAL next to the existing one, this is also possible. But in this case you will have to position your second fan slightly behind the first because they are too big to be able to put them side by side. For this, spacers or washers will be used at the level of the fixing.

Here are the 2 fans with their fixing kits.

The composition of a fan assembly kit.

We start by gluing the foam pads to the 4 ends of the fan.

Once the 4 foam pads have been glued.

The fan is positioned on the radiator.

Insert a first rod through the fan.

It is passed through the radiator beam by gently pulling on it without forcing it.

These operations are repeated for the other 4 rods.

Then we insert a rubber pad on the other side of the radiator core.

We then block it with the washer.

Cut off the excess rod using wire cutters.

Repeat the operation for the 4 other bindings, and you’re done!


Same thing for the second fan… and the assembly is finished!
Electrical connections of the fan (s)
We will now have to connect all these little people electrically . For this, I advise you to buy a 12V accessory connection kit , containing everything necessary to make a clean connection of your fan (s) (wires, 12V relay, fuse and fuse holder).

You will also need to install a switch in the passenger compartment to manually operate your fan. You can recover an original one in breakage or on the right corner, to integrate it directly on your dashboard (below the warning switch for example). Otherwise, you will have to buy a “universal” switch and adapt it as you can by simply placing it within reach of the driver.

Addition of a switch integrated into the dashboard …
… Or on a turntable!
Here is the diagram of the electrical connection to be made:

This assembly with 12V relay and fuse is the most reliable and secure installation . It will thus make it possible to trigger one of the fans directly from the passenger compartment. For the other fan, the electrical connection is identical except that the manual switch is replaced by the sensor located at the bottom of the radiator and which allows the fan to be triggered automatically at a given temperature (this is the original assembly on the first fan).

4th step (strongly recommended): fitting a temperature manometer
The 4L is not originally equipped with a water temperature gauge (also called a “temperature manometer). A simple red light on the dashboard tells us that the coolant temperature is too high and that our engine is overheating.

When we are there, it is because it is already “too late”. What interests us here is to travel through Europe without having an engine overheating. In short, prevention is better than cure. And for that, a solution: install a temperature manometer!

The latter is made up of two elements: the pressure gauge (dial) which is installed in the passenger compartment and a probe which will have to be connected to the cooling circuit. For this, several techniques:

we install a sleeve on a water hose to be able to connect the probe.
the sensor is screwed in place of the small drain screw on the distribution side (Cleon engine).
The dial, for its part, can be installed on a plate integrated into the dashboard or on an independent support.

Once mounted, it will allow us to control the engine temperature in real time and react accordingly if the temperature starts to rise … hence the interest of being able to manually trigger its second fan!🙂

Here the temperature manometer is installed on a plate integrated into the dashboard (left). At the bottom of the plate, we have the switches that allow manual control of the fans if necessary.
5th step (optional): assembly of an electric water pump
If with all this, your 4L does not cool better, we will therefore take out the heavy artillery, I named: the electric water pump! This kind of pump is generally mounted on cars intended for competition, as much to say to you that now, one does not joke any more!😀

Why install an electric water pump?
Using an original mechanical water pump (belt driven), the water circulation on our 4L depends on your speed:

at low speed (engine at idle: traffic jams, reduced speed in town) the water pump also idles and the engine is therefore poorly cooled;
at high speed , the pump speed is too high and the water tends to “cavitate” thus preventing proper cooling.
The electric water pump runs at constant speed: it will therefore allow all these faults to be overcome by improving the circulation of water in the cooling circuit whatever your speed while increasing the life of your engine. The cost of such a pump is unfortunately very high .

This is an additional water pump that is added to the cooling circuit, to the hose at the radiator outlet (bottom right), making the connection with the mechanical water pump. The best is to operate it through the electric fan probe, so that it is triggered at the same time as it when the water temperature becomes too high.

How to assemble an electric water pump?
I made a tutorial for mounting an electric pump on my 4L, which you can find on this site: electric-water-pump /

Be careful though, fitting an electric water pump is not a trivial operation and will require some irreversible modifications in the engine compartment: cutting out the battery tray, cutting and modifying the lower water hose. To be carried out only with full knowledge of the facts.


Contents of the electric water pump kit.

Electric water pump in place in the engine compartment of the 4L.
6th step (optional): mounting an aluminum radiator
It is certainly very expensive, but it is a must! Lighter and bigger, it could reduce the coolant temperature more quickly thanks to better heat exchange . I have never fitted this type of radiator on my 4L because I find the cost extremely high (between around € 250 and € 300). So I can’t tell you at the moment if this brings a noticeable improvement in cooling. But in principle and from what I heard, it clearly makes the difference!

You can find these aluminum radiators sold alone or as a kit with 2 electric fans at:

Axauto-parts .
They exist for Cléon engines but also for Billancourt now.

It is not essential to participate in Blue Rally Europe , but if you have the budget, it can be a big plus to limit the risk of engine overheating as much as possible and thus drive serenely.

Aluminum radiator only for Renault 4L with Cléon engine.
Aluminum radiator kit + fans from Axauto-parts.

If you’ve made it this far, it’s because you’ve read the entire first part and you’ve already applied my advice on your 4L … 😉

You have therefore normally put all the chances on your side to optimize the cooling of your 4L as well as possible and thus avoid overheating during the raid. However, despite all these precautions taken, this may not prove to be sufficient in extreme conditions : significant climbs to climb, scorching temperatures, altitude, etc.

This part will therefore be devoted to last resort solutions when your 4L starts to overheat.

3 last resort tips to avoid overheating
Unlock your hood so that it opens slightly: all you have to do is press the hood release lever to open slightly. This allows the engine compartment to breathe a little better since the air entering through the grille can be exhausted more easily. Better air flow = better cooling.
At the same time, turn on your heating fan and put the valve in the heating position (red button side). This will allow the coolant to circulate a little more and be cooled by the interior heater fan. It is not very pleasant, I agree, especially since we are generally quite hot enough already in the 4L, but it is better than to overheat and break a cylinder head gasket … Hence the interest of installing a small 12V fan plugged into the passenger compartment to better ventilate the interior of the 4L and help you withstand the heat.

If you are stationary (traffic jam for example), do not hesitate to accelerate slightly (in neutral) . This will give more efficiency to the water pump which will make the water circulate more quickly in the circuit. The water (coolant) will thus be cooled better.Do you have any other questions concerning the preparation of your 4L for the Blue Rally Europe and in particular on the question of cooling? Do not hesitate to post them in comments at the bottom of the article , I always answer them!


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