folks, my local mechanic (without checking with me) did this.he used a screwdriver to bend the bimetallic strip on the fan clutch outward (towards the radiator) - i think this makes the clutch engage earlier?the temp gauge is now about two notches below mid-point. however the engine roar is louder - due to tighter fan engagement?my questions:1. how do i know if the clutch still behaves normally during cold - is it supposed to free wheeling only when the engine is cold from overnight stop?2. any reliability issue?3. anyone thought of this before?
E34 fan clutch bimetallic strip mod
- Thread starter ktteoh
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The bimetallic strip basically control the fluid coupling of the cluth. When it is cold, less oil will flow thru the coupling making it go slower. When the engine is hot, the bimetallic strip will expand and allow more oil to flow and make it go faster.
What your mechanic have done is to allow oil to flow more and cause the fan to spin faster and cool the engine more.
There are pro and con in doing this..
pro..
The engine runs at a lower temperature. It is quite useful if you are stuck in a traffic jam and on a hot day.
con..
Slightly more load on engine as you need to tap a bit more power to rotate the fan.
Engine not running at optimum temperature.
I have done mine by adding a bit silicon oil rather than bending the strip. Temperature running at lower notch. About two clicks but still above the blue or cold zone. Feel more easy as engine is running at slightly lower temperature.
btw mine is e36. not sure yours is the same principle.
What your mechanic have done is to allow oil to flow more and cause the fan to spin faster and cool the engine more.
There are pro and con in doing this..
pro..
The engine runs at a lower temperature. It is quite useful if you are stuck in a traffic jam and on a hot day.
con..
Slightly more load on engine as you need to tap a bit more power to rotate the fan.
Engine not running at optimum temperature.
I have done mine by adding a bit silicon oil rather than bending the strip. Temperature running at lower notch. About two clicks but still above the blue or cold zone. Feel more easy as engine is running at slightly lower temperature.
btw mine is e36. not sure yours is the same principle.
kevster30
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ktteoh;212714 said:
What the mechanic did was to permanantly lock-up your fan clutch. The clutch is now cpmletely locked and it is irreversible. The mettallic strip acts as a clutch spring to provide pressure into the clutch assembly.
1. The clutch will no longer spin freely as it is locked.
2. No reliability issue. Fuel consumption and power delivery will suffer as there is a permanant load on the crankshaft.
3. The fanclutch is designed with this feature. Should your clutch wear out and you are far away from a replcement, just do this and all will be fine.
wow, learn something new everyday. now i got to check tomoro morning when cold start. see if the fan spins freely or is locked.
just curios, i've seen some cars when u switch off the engine, the fan stop immediately. but on mine, it still spins for a while, then stops. this is when the temperature is at normal operating levels.
and on some cars, when during hot weather or traffic jams, its just slighty over the middle mark. but on mine its never full on the middle mark, always just very slightly below.
is it normal that on different cars, it differs?
just curios, i've seen some cars when u switch off the engine, the fan stop immediately. but on mine, it still spins for a while, then stops. this is when the temperature is at normal operating levels.
and on some cars, when during hot weather or traffic jams, its just slighty over the middle mark. but on mine its never full on the middle mark, always just very slightly below.
is it normal that on different cars, it differs?
Iqlima;212811 said:
Did mine at a shop in Skudai (H-2) when I have some engine trouble. Cost me about RM80 for the oil and modification. Unlike the bending of the bi-strip, this mod make the fan spin faster or earlier but still have the slip at cold condition.
BTW, you don't have to start the engine to check the cluth. Just turn the fan when the engine is OFF. It should turn freely with a bit of resistance. For the more adventurous, you can start the engine and try to stop the fan when it is rotating. it should stop when you put your hand on the blade. (Wear a glove to protect your fingers or you may up end loosing it).
hello
i do have the old bmw fan clutch still if that means anything and it was working fine till the incident. should i still purchase a new one? and the fan shroud was torn to pieces so i'll need a new one. do you think that is the cause of the problem since the fan is running nonstop? cause it's also been suggested to me that it's the thermostat.
i do have the old bmw fan clutch still if that means anything and it was working fine till the incident. should i still purchase a new one? and the fan shroud was torn to pieces so i'll need a new one. do you think that is the cause of the problem since the fan is running nonstop? cause it's also been suggested to me that it's the thermostat.
danzel;227409 said:hello
i do have the old bmw fan clutch still if that means anything and it was working fine till the incident. should i still purchase a new one? and the fan shroud was torn to pieces so i'll need a new one. do you think that is the cause of the problem since the fan is running nonstop? cause it's also been suggested to me that it's the thermostat.
The fan clutch is always spinning whenever the engine is running. In the beginning, it will spin slowly. When the water in radiator get hot, air passing thru the radiator will heat up the bimetallic strip of the fan clutch. This will in turn make the bimetallic strip to bend outward and allow more silicon oil to flow and hence make the fan to spin faster. When the fan spin faster it will cool the radiator faster and will keep the radiator operating at optimum temperature. Vice-versa, when the temperature in the radiator dropped, the bimetallic will contract and reduce the speed of the fan.
