[rex4585]

Check your cooling fan viscous coupling when your engine is cold. Is it turning freely?
If it feels tight does your engine make a loud wind noise when accelerating and the engine sounds strained?
Do your check engine light sometimes comes on and the water temperature gauge drops to the bottom. Then the aircon begins to feel warm.
When check with a fault reader it says coolant sensor failure. The water temperature gauge is at 1/4 when idling with aircon on. It shoots up almost immediately on rapid acceleration.
After I change the viscous coupling all became normal and the engine sounds so sweet when accelerating rapidly. Much better pickup and better diesel consumption. Wasted my money changing the coolant temperature sensor which was not faulty. Heard from the mechanic who agree with my views regarding the coupling and change it for me that another Rexton had the coolant sensor changed By him but the above symptoms remain. He did not check the viscous coupling then. Never occur to him to check that. My earlier mechanic says the coupling is good as it must feel a little tight when turned manually. He disagreed with me that it is faulty. In fact the new one is very free spinning.
Please note that the coupling for some Mercedes are same as that of the Rexton 270. May be cheaper than original. I fix one from a Mer.
Check your cooling fan viscous today. Can improve your fuel economy and your enjoyment of Rexton or any vehicle with viscous coupling.

[r3xt0n]

Check your cooling fan viscous today. Can improve your fuel economy and your enjoyment of Rexton or any vehicle with viscous coupling.

Thanks for sharing the info. Good that we have another Defect Symptom solved.

Some bros did encountered temperature gauge dropped suddenly and aircon become warm but it recovered back quickly. Right, the Scanner reported Coolant Sensor problem but not too costly to replace. I think no one replaced their Cooling Fan Viscous yet.

[byebye2u]

Thanks for sharing the info. Good that we have another Defect Symptom solved.

Some bros did encountered temperature gauge dropped suddenly and aircon become warm but it recovered back quickly. Right, the Scanner reported Coolant Sensor problem but not too costly to replace. I think no one replaced their Cooling Fan Viscous yet.

thanks for sharing.

I have the problem too previously, almost weekly. because of the sound coming from the belt, I spray 4w-40 on all the pulley and the fan coupling, then when starting the engine I make sure the check engine light went-off before cranking. sometime once in a month it happen too, so I just follow the above procedure and set the air-cond temperature to minimum...funny but the problem solve.

[rex4585]

The aircon only become warm when the temperature setting is not at low and the weather cool. However if you off the ignition and restart then it returns to normal. Nothing to do with WD40. Also if you slow down then it may become ok after sometime.
Before I found the problem I never expert the engine roar on acceleration is connected to the coolant sensor or the aircon. Wasted my auto electrician time trying to find the problem. Hope I have help some Bros.

[r3xt0n]

The aircon only become warm when the temperature setting is not at low and the weather cool. However if you off the ignition and restart then it returns to normal. Nothing to do with WD40. Also if you slow down then it may become ok after sometime.
Before I found the problem I never expert the engine roar on acceleration is connected to the coolant sensor or the aircon. Wasted my auto electrician time trying to find the problem. Hope I have help some Bros.

I experience once when I was in Cameron Highland. The water temperature dropped suddenly and aircon become warm but it recovered back after a minute or two. Did not occur again, so did not check it out further.

[razopower]

Check your cooling fan viscous coupling when your engine is cold. Is it turning freely?
If it feels tight does your engine make a loud wind noise when accelerating and the engine sounds strained?
Do your check engine light sometimes comes on and the water temperature gauge drops to the bottom. Then the aircon begins to feel warm.
When check with a fault reader it says coolant sensor failure. The water temperature gauge is at 1/4 when idling with aircon on. It shoots up almost immediately on rapid acceleration.
After I change the viscous coupling all became normal and the engine sounds so sweet when accelerating rapidly. Much better pickup and better diesel consumption. Wasted my money changing the coolant temperature sensor which was not faulty. Heard from the mechanic who agree with my views regarding the coupling and change it for me that another Rexton had the coolant sensor changed By him but the above symptoms remain. He did not check the viscous coupling then. Never occur to him to check that. My earlier mechanic says the coupling is good as it must feel a little tight when turned manually. He disagreed with me that it is faulty. In fact the new one is very free spinning.
Please note that the coupling for some Mercedes are same as that of the Rexton 270. May be cheaper than original. I fix one from a Mer.
Check your cooling fan viscous today. Can improve your fuel economy and your enjoyment of Rexton or any vehicle with viscous coupling.

Thanks Bro Rex4585 for sharing. But for my experience with my pajero, the viscous fan or rather the " Fan clutch" is serviceable. My mechanic took out the fan clutch and replace with new oil. The oil is quite costly, around RM 30 for a little tube only.

I am not sure if our rex viscous fan can be service ?

[mckhairie]

Check your cooling fan viscous coupling when your engine is cold. Is it turning freely?
If it feels tight does your engine make a loud wind noise when accelerating and the engine sounds strained?
Do your check engine light sometimes comes on and the water temperature gauge drops to the bottom. Then the aircon begins to feel warm.
When check with a fault reader it says coolant sensor failure. The water temperature gauge is at 1/4 when idling with aircon on. It shoots up almost immediately on rapid acceleration.
After I change the viscous coupling all became normal and the engine sounds so sweet when accelerating rapidly. Much better pickup and better diesel consumption. Wasted my money changing the coolant temperature sensor which was not faulty. Heard from the mechanic who agree with my views regarding the coupling and change it for me that another Rexton had the coolant sensor changed By him but the above symptoms remain. He did not check the viscous coupling then. Never occur to him to check that. My earlier mechanic says the coupling is good as it must feel a little tight when turned manually. He disagreed with me that it is faulty. In fact the new one is very free spinning.
Please note that the coupling for some Mercedes are same as that of the Rexton 270. May be cheaper than original. I fix one from a Mer.
Check your cooling fan viscous today. Can improve your fuel economy and your enjoyment of Rexton or any vehicle with viscous coupling.

Bro, what is the price for the viscous coupling. My ride now having same symptoms...

[rex4585]

Bro, what is the price for the viscous coupling. My ride now having same symptoms...

Bro sorry don't know costof new one. Mine is a 2nd hand unit from a Merc. Only RM 150 fitted and guaranteed good before I pay. Looks pretty new. Plenty of 2nd hand Merc parts around. Maybe can compare Merc and Rexton prices.
Good luck and keep us posted.

[r3xt0n]

Bro sorry don't know costof new one. Mine is a 2nd hand unit from a Merc. Only RM 150 fitted and guaranteed good before I pay. Looks pretty new. Plenty of 2nd hand Merc parts around. Maybe can compare Merc and Rexton prices.
Good luck and keep us posted.

Yes, it shared lots of Merc parts but cost a fraction of it. That's the beauty of Rexton.

[teerex]

Thanks Bro Rex4585 for sharing. But for my experience with my pajero, the viscous fan or rather the " Fan clutch" is serviceable. My mechanic took out the fan clutch and replace with new oil. The oil is quite costly, around RM 30 for a little tube only.
I am not sure if our rex viscous fan can be service ?

Hi Bros,
Found this from the net.
The units operation consists of two main parts
• The viscous coupling.
In the housing there is a wheel with fine grooves which runs in the also finely grooved housing to which the fan blades are attached. Between the housing and the wheel is silicone oil. Now a property of this oil is that it's viscosity is not so much depending on temperature (as with normal oil) but on velocity. The greater the oil velocity the greater the viscosity. The greater the difference in speed between the oil layer on the housing and the oil layer at the wheel the thicker the oil becomes and so the wheel (which is attached to the water pump shaft) takes the housing with it and the fan turns. As the fan speeds up the speed difference decreases and the silicone oil gets thinner....thus less driving force.....this system prevents the fan from over revving and limits it turning speed at about 2500 rpm
There are two ways this beautiful thing can let you down
• By locking itself up
The grooves are very thin and probably can break due to vibrations of the fan blades, engine,etc. this could lead to a lock up between wheel and housing resulting in an over revving fan. It can be clearly heard because suddenly the fan makes a very loud noise, especially when the engine is revving hard. There is a chance that a fan blade breaks off, this can cause such an unbalance that more blades also try to find their way to freedom. But even more damage can be done. Because the blades push air towards the engine, when a blade comes off the reaction forces move the blade forward against the radiator!. Now if your unlucky this can result in a damaged (even leaky) radiator.
• By not picking up the revs
When the connection between the housing and the wheel isn't good enough the fan blades will turn slower than desired. This can result in overheating of the engine. especially when driving in a queue, town driving or towing. Reasons for this happening can be some loss of silicone oil along the drive shaft,or a seized oil plate You can check this by carefully (!!!can be dangerous!!!!) trying to press a thick cloth against the fan blades when the engine is at operating temperature and idling. If you can stop the fan...the unit is faulty and should be replaced.
New viscous couplings are quite expensive. so trying to find a good second hand one might be worthwhile. However it is impossible to see what state a 2nd hand one is in. It might fail as well within a year or give good service for years and years. It is also possible to use viscous fan from other engines.
An electric fan?
Maybe you'll ask, why don't you install an electric fan. It is possible and using an electric fan has its own advantages and disadvantages.
Advantages
• An electric fan is cheaper than a viscous fan,especially when using one from a scrap yard
• The fan doesn't absorb any power when it's not in use
• You can switch the fan on/off by yourself if you by-pass the electric thermostat
Disadvantages
• The viscous fan is always blowing some air through the engine bay. An electric fan only when the water temperature is high. So the viscous fan provides a cooler engine bay which is better for the electric components
• With an electric fan you introduce more wiring, thermostat, electric motors which can fail