While the temperature itself is well within spec, given the day wasn’t really that hot compared to days in the mid 40s we get here in Sydney, I wanted to do something about it.   Additionally, the air conditioning doesn’t cool properly when the engine is at those sort of temperatures.   This is presumably due to the R134A gas not being as efficient as R12.

The first step was to replace the radiator cap as it is likely not holding pressure properly.    This is a simple fix.   I know the radiator works properly as the engine was running too cool in winter before I had the thermostat changed.   In hot weather the car has two systems to keep cool.   The first is the M117 fan clutch.    The second is the electric auxiliary fan.  The focus of this article is the fan clutch.

On older cars, the fan is connected directly to the water pump and spins at the same speed as the engine.   This wasteful as most of the time this much air flow is not needed.   The fan clutch assists here by allowing the fan to spin slower under normal circumstances.  However, when the temperature reaches a prescribed level the fan can spin faster.    It generally won’t spin at a 1:1 ratio but will be limited to a particular RPM that is efficient for max airflow.

My 560SEL is equipped with such a fan clutch, as are other W126 models.   When the engine is hot, you should be able to hear the fan roar when you rev the engine and I never heard this.   Additionally, if you turn the car off when the engine is very hot, it should be hard to spin the fan.   On my car it wasn’t.   As the M117 fan clutch in my car was the original unit, it seemed like a good idea to change it.

It is a very easy job.   The M117 fan clutch is held on by four 10mm bolts.   There is no need to remove the radiator or even the top radiator hose.  All that is required is to loosen the shroud so the fan assembly can be removed.

Once the fan assembly is removed from the car there are four more 10mm bolts holding the fan to the clutch.  I used a rubber mallet to remove the old clutch from the fan.   The new one looks a bit smaller and doesn’t have the plastic protector like the old one.   It is made in China, so I hope it lasts 33 years and 328,000km like the old one did.

The picture above shows the original M117 fan clutch, with the 1987 date on it.

Once the new clutch is installed then the installation is the reverse of the removal.   One trick I picked up on some forums was to put the lowest of the four bolts in first.   The fan assembly doesn’t attach through hole – there are cut outs.   This allows the fan assembly to slip onto the bolt to locate it before the others are installed.   The photo below shows the whole assembly removed before re-installation.

I have not been able to test the success of this job yet.   It was 15C and raining today.   This is probably the last cold snap before a hot summer, so I doubt it will be long.   I also need to test the operation of the electric auxiliary fan.

The post M117 Fan clutch appeared first on .

My car, being a carburetor DS21 does not have this improved radiator / electric fan combination.    The Citroen DS cooling system worked quite well when the cars were new.  However, a combination of the hot Australian climate and an almost 50 year old car that spent quite a lot of time in South Australia means that my cooling system struggles in stop and go traffic.   For international readers, South Australia has very hard water resulting in mineral deposits if distilled water is not used.

While I was having some other work done, I had a Davies, Craig fan fitted behind the radiator.  This is to augment, not replace the mechanical fan.   The setup is basically the same as the Citroen DS electric cooling fan.   Over the years people have tried to replace the mechanical fan entirely. This is a recipe for disaster as the electric fans cannot pull enough air at high speed with no ram effect.     The Davies, Craig fan is equipped with a controller that allows adjustment of the cut in point.

I also wanted to know when the fan is running.   The Citroen DS instrument cluster has an extra warning light that is not used in my car.   This is for parking lights.   The spot for this warning light was taped up.   I have a spare instrument cluster for parts, so I was able to grab another bulb housing to enable this extra light.

Looking at the parts instrument cluster the tape used to disable the warning lights not in use from the factor can be seen.   This is at the 12 and 6 O’Clock positions.   From there, it is relatively easy to run another wire to the back of the instrument cluster for the warning light.   The speedometer cable is already running right past this area.    The connections on the back of the cluster are well documented.

I would have preferred a green or orange warning light, but the red one is fine.    It works quite well.   I took the car for a drive in the 30 degree heat and the light was on for quite a lot of the time, but it did cycle on and off as the fan kicks in/out.   The fan is wired to be ‘always on’.   This means that after the car is turned off, the fan will continue to run if the engine is hot enough to warrant it.  I did this because heat soak can be an issue in these cars.   On my test drive, it ran for about 10 minutes after I switched off the car.   The risk is draining the battery, but on a hot day this is a useful feature for a short stop.

I don’t want my cars to be garage queens.  This modification, while not factory should make the car more usable in Summer.

The post Citroen DS electric cooling fan appeared first on .

When I had bypassed the switch, I broke one of the connectors off the Lucas relay that controls the fan.   Therefore, I ordered an upgraded temperature sensor from Coolcat.   I also ordered a new Lucas relay from XKs Unlimited, trying to get the same one I already had.   This was for two reasons.  Firstly, it looked good compared to the normal black square relays, and secondly the mounting tab was already there and in the right place.

While I waited for these parts, I bypassed the temperature sensor and let the fan run all the time.   It was summer in Sydney so it would have run much of the time anyway.   On a drive in November, the fan failed again.   This time it had blown the fuse.    I resolved to fix this properly before I drove the car again.

The way the relay had been wired in baffled me.   It was using the same source for both the main 12v feed and the switching source.   Even though the E-Type radiator fan does not draw very much current, it seemed odd to wire it up this way.   My car has the Coolcat fan, which draws similar current to the stock fan.

I therefore ran a 12v power source with in-line fuse to the relay and used the car’s normal power source just to switch the relay on.   This should prevent the fuse from blowing.    I started with a 10A fuse as the fan is rated at 7, but it blew this so I went to a 15.  It would appear that the starting current is a little higher.

Unfortunately, while the picture on the XKs Unlimited website showed the same red cylindrical relay I had previously, the one that arrived was a regular black square one, except it was made by Lucas.    I was about to drain the coolant on the header tank to replace the switch, when it occured to me to test the one I had first.  I knew my original problem was either switch or relay.   Since I had broken the original relay disconnecting it, it made sense to test the switch with the new relay.   Lo and behold, it worked fine.    I now have a spare sensor, and a working car.

After that, I took the car on an extended drive up to Gosford via the old Pacific Highway and the fan performed as it should.   I made sure I included a spare fuse in he car, but luckily I didn’t need it.

Until I can source the correct relay, I have used a zip tie to attach it to the mounting point.   At that time, i will try and tuck in the new red wire a little better.    The sticker on the radiator header tank shows the temperature.   Great for checking the fan sensor is working!

It was good to get behind the wheel of the E-Type after a couple of months.  Even better that it didn’t overheat.    I continue to be very happy with the diff ratio change I did.   Third gear is now a useful gear for twisty roads, like it should be.    In addition, the halogen lights are excellent, better than even cars from the 80s.   The E-Type series one is known for poor lighting, bug once its upgraded to Halogen it’s great!

The post Troubleshooting the E-Type radiator fan appeared first on .

On the way back from the British Car Show, I noticed after I got off the freeway that the temperature was steadily climbing.   It was not a particularly hot day, nor was traffic a real problem for me.    Once the temperature reached 110c, I pulled over to see why.

On examination, I found my problem, E-type radiator fan failure.   This left me with a problem – I needed to drive through a high traffic area, so a working radiator fan would be essential.   Unfortunately while I had a tool kit, I didn’t really have much in the way of electrical supplies.   What I did have was a set of jump leads.   I was able to use a jump lead to test the fan directly from the battery and the fan still worked.  As soon as I applied 12v, it sprang into life and started to drop the temperature.    Running this for a few minutes got the temperature down to 70C.

One must be careful to not get the cable caught in the little fan for the alternator.  I did and I was left with two halves of the jumper cable.   This was actually ok.  I was able to use some masking tape to connect the fan wire to the severed end of the cable and limp the car home.   The masking tape also allowed me to properly insulate the 12v source.

The learning from this is that it is probably wise to carry some electrical tape and wire in the toolkit in each car.   It also shows that while older cars are less reliable than modern ones, if you run into trouble you have a much better chance of making a temporary repair to limp home.    I have not properly troubleshooted the issue, but I suspect either the temperature sensor or the fan relay.   Regardless of the problem I need a new relay.  I broke the current one trying to disconnect it from the fan.   This is unfortunate as I suspect it is the sensor.   In the meantime I can wire up an always on solution until I get new parts.

The post E-Type radiator fan failure appeared first on .