Cooling System Problem Review - Chapter 3
#1
07-07-2012, 03:17 PM
Cooling System Problem Review - Chapter 3
Previous chapter - https://landroverforums.com/forum/ge...ter-2-a-51022/
Chapter 3 - Fan, Clutch, and Serpantine Belt
A plastic fan is mounted on a viscous clutch screwed to the water pump. The fan is enclosed by a shroud which increases the effectiveness of the fan.
The water pump is turned by a serpantine belt. If the belt is routed incorrectly after repairs, the water pump and fan may turn in the wrong direction.
Route for a D1 and similar - Serpentine Belt Routing Maintenance For The Discovery I, Range Rover Classic And Defender 90
Route for D2 - Discover Land Rover Discovery Serpentine Belt Routing Maintenance Tips
The belt can shred , wear out (cracks, splits, ribs missing). If soaked in degreaser, it can slip and provide reduced cooling and alternator output.
The viscous clutch when started after overnight parking will engage fully (about 60-70 % power transfer), because the silicone fluid inside has pooled to one side. This can make a fan "roar" noise, which goes away quickly as truck warms up and silcone fluid is circulated inside the clutch. The clutch reduces power transfer to about 20% at normal operating temperature, to reduce drag on engine. The clutch works by the fluid expanding as it warms up (face of the clutch gets to 170F or so). When engine gets hot, clutch will re-engage at full power to provide more air flow thru radiator whne parked or at slow speeds. The "roar" returns.
The fan clutch can be tested by spining it and releasing when engine is cold. It should feel like peanut butter inside, and not spin more than a fraction of a turn when released. When truck is warmed up, shut off, and test repeated, it should still not spin more than one turn. A freewheeling clutch needs to be replaced, the fluid has been lost. A cross over from a Chevy 2000 4.3 liter van, with/out air, can be used, around $50. See https://landroverforums.com/forum/di...acement-32370/. The fan clutch is a six inch reverse rotation model, and is also shared by a number of GM vehicles, making an emergency replacement available at many junk yards. Some owners have installed alternative fans, both metal and plastic. Getting the clutch off is not easy, but can be done by a DIY. Basically you attache a wrench to the water pump bolt on the fan shaft. Use anothe wrench to lean on the belt tensioner to increase tension on the belt. Hit fan clutch wrench hard and sharp, to the left (when standing in front of truck facing the engine).
If replacing the clutch, ask the parts guy if it is stored vertical, it should be. Take home keeping vertical, and be sure it stays vertical in one position for 24 hours, this makes sure fluid is pooled to one side. Laying flat before install can cause problems in certain clutches.
The fan can come apart at speed if a blade is damaged, and parts dropped into the fan shroud have a nasty habit of being flung into the radiator. Working around moving and rotating parts calls for safety precautions, eye protection, long hair tied back, etc.
Chapter 4
Chapter 3 - Fan, Clutch, and Serpantine Belt
A plastic fan is mounted on a viscous clutch screwed to the water pump. The fan is enclosed by a shroud which increases the effectiveness of the fan.
The water pump is turned by a serpantine belt. If the belt is routed incorrectly after repairs, the water pump and fan may turn in the wrong direction.
Route for a D1 and similar - Serpentine Belt Routing Maintenance For The Discovery I, Range Rover Classic And Defender 90
Route for D2 - Discover Land Rover Discovery Serpentine Belt Routing Maintenance Tips
The belt can shred , wear out (cracks, splits, ribs missing). If soaked in degreaser, it can slip and provide reduced cooling and alternator output.
The viscous clutch when started after overnight parking will engage fully (about 60-70 % power transfer), because the silicone fluid inside has pooled to one side. This can make a fan "roar" noise, which goes away quickly as truck warms up and silcone fluid is circulated inside the clutch. The clutch reduces power transfer to about 20% at normal operating temperature, to reduce drag on engine. The clutch works by the fluid expanding as it warms up (face of the clutch gets to 170F or so). When engine gets hot, clutch will re-engage at full power to provide more air flow thru radiator whne parked or at slow speeds. The "roar" returns.
The fan clutch can be tested by spining it and releasing when engine is cold. It should feel like peanut butter inside, and not spin more than a fraction of a turn when released. When truck is warmed up, shut off, and test repeated, it should still not spin more than one turn. A freewheeling clutch needs to be replaced, the fluid has been lost. A cross over from a Chevy 2000 4.3 liter van, with/out air, can be used, around $50. See https://landroverforums.com/forum/di...acement-32370/. The fan clutch is a six inch reverse rotation model, and is also shared by a number of GM vehicles, making an emergency replacement available at many junk yards. Some owners have installed alternative fans, both metal and plastic. Getting the clutch off is not easy, but can be done by a DIY. Basically you attache a wrench to the water pump bolt on the fan shaft. Use anothe wrench to lean on the belt tensioner to increase tension on the belt. Hit fan clutch wrench hard and sharp, to the left (when standing in front of truck facing the engine).
If replacing the clutch, ask the parts guy if it is stored vertical, it should be. Take home keeping vertical, and be sure it stays vertical in one position for 24 hours, this makes sure fluid is pooled to one side. Laying flat before install can cause problems in certain clutches.
The fan can come apart at speed if a blade is damaged, and parts dropped into the fan shroud have a nasty habit of being flung into the radiator. Working around moving and rotating parts calls for safety precautions, eye protection, long hair tied back, etc.
Chapter 4
Last edited by Savannah Buzz; 07-16-2012 at 05:14 AM.
#2
01-08-2013, 09:47 PM
Three Wheeling
#3
01-08-2013, 10:01 PM
Ouch. A chevy "cross over" fan clutch is maybe $70. And in a pinch, one from a Chevy or GMC in the boneyward is like $19. When you say freewheeling, to me that would mean that with engine off, you spin and release the blades, and they keep going a full revolution or more. They should stop in just a part of a revolution, and feel like there is peanut butter inside the unit, instead of air. You can of course turn the fan 360 degrees by hand, it is not "latched". Note to others - please don't try stopping the fan with rolled up newspapr or grabbing it by hand at idle. You don't want to be known as "Stubby."
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