Condenser fan / Radiator fan
Discussion
My 1996 (E34) 525i has an auxiliary cooling fan (electric) on the front of the A/C condenser and a viscous fan behind the radiator, neither of which are working properly. The car has been taken off the road for various repairs and improvements so obviously I want to fix this.
Could I possibly ditch both fans and fitted a single mammoth electric fan to the back of the radiator to cover both functions? i.e. a two speed fan which cuts in with the A/C and runs at speed two at high engine temperature?
With a well-fitted shroud, would a large electric fan on the rear of the radiator act as an effective replacement for the electric fan the E34 normally has fitted to the front of the A/C condenser?
Could I possibly ditch both fans and fitted a single mammoth electric fan to the back of the radiator to cover both functions? i.e. a two speed fan which cuts in with the A/C and runs at speed two at high engine temperature?
With a well-fitted shroud, would a large electric fan on the rear of the radiator act as an effective replacement for the electric fan the E34 normally has fitted to the front of the A/C condenser?
Yep the viscous clutch unbolts from the fan (which is fine). A decent quality replacement will be comfortably under £100 I'd have thought.
In any case saving money isn't really the target, I just wondered if things had moved on a bit in the intervening 20 years which might make one electric fan a sensible way to go.
The auxiliary cooling fan motor looks pretty serviceable, it looks as though it's in decent order inside apart from two detached magnets which have seized the thing solid, so there's a possibility that with a bit of araldite and some patience the motor could be repaired so that's my first line of investigation
If I can revive the electric fan I'll stick with the viscous engine fan just for the sake of simplicity and originality.
In any case saving money isn't really the target, I just wondered if things had moved on a bit in the intervening 20 years which might make one electric fan a sensible way to go.
The auxiliary cooling fan motor looks pretty serviceable, it looks as though it's in decent order inside apart from two detached magnets which have seized the thing solid, so there's a possibility that with a bit of araldite and some patience the motor could be repaired so that's my first line of investigation
If I can revive the electric fan I'll stick with the viscous engine fan just for the sake of simplicity and originality.
I doubt an electric fan would cool any better. Maybe a tiny bit more fuel efficient. If you are changing I think 2 small electric fans will be more efficient than 1 big one + you'd have a backup if one failed.
I'd be inclined to stay with the original set up, for the sake of simplicity and reliability.
ETA
I quite like engine driven fans, even when free-wheeling the're moving a bit of air around the engine bay.
I'd be inclined to stay with the original set up, for the sake of simplicity and reliability.
ETA
I quite like engine driven fans, even when free-wheeling the're moving a bit of air around the engine bay.
Edited by PositronicRay on Saturday 20th February 14:44
One large,modern powerful (brushless) fan would indeed replace both fans, with the proviso you find some way to control the fan from two sources!
The engine coolant rad needs a fan when coolant temps exceed a certain temperature and the A/C condensor rad needs extra air when the a/c system in running. If you replace both fans with a single one, you'll have to work out how to wire it t come on when either system wants to be cooled. (Usually with a 'lecy fan it comes on at low speed when the a/c system is on, and then on at higher power when the engine wants cooling)
The engine coolant rad needs a fan when coolant temps exceed a certain temperature and the A/C condensor rad needs extra air when the a/c system in running. If you replace both fans with a single one, you'll have to work out how to wire it t come on when either system wants to be cooled. (Usually with a 'lecy fan it comes on at low speed when the a/c system is on, and then on at higher power when the engine wants cooling)
Max_Torque said:
One large,modern powerful (brushless) fan would indeed replace both fans, with the proviso you find some way to control the fan from two sources!
The engine coolant rad needs a fan when coolant temps exceed a certain temperature and the A/C condensor rad needs extra air when the a/c system in running. If you replace both fans with a single one, you'll have to work out how to wire it t come on when either system wants to be cooled. (Usually with a 'lecy fan it comes on at low speed when the a/c system is on, and then on at higher power when the engine wants cooling)
What a load of rubbish.A 1 fan setup will never be as good as a 2 fan front and back setup.As for your suggestion of a brushless motor,that is another load of rubbish,if the brushless motor is of the magnetic variety it will get hot in the radiator area when stood still and when sunlight is on it and it will lose its magnetismThe engine coolant rad needs a fan when coolant temps exceed a certain temperature and the A/C condensor rad needs extra air when the a/c system in running. If you replace both fans with a single one, you'll have to work out how to wire it t come on when either system wants to be cooled. (Usually with a 'lecy fan it comes on at low speed when the a/c system is on, and then on at higher power when the engine wants cooling)
Think before you post
And the man will not control the circuits in an easy way
And it would all need reshrouding and still not be good enough
The best way is to keep it as standard, but you wouldnt suggest that would you
Baaaaaaaaaaaaaaaaaaaaad Info that must be ignored
Edited by Dissapointed1 on Saturday 20th February 15:10
Dissapointed1 said:
Max_Torque said:
One large,modern powerful (brushless) fan would indeed replace both fans, with the proviso you find some way to control the fan from two sources!
The engine coolant rad needs a fan when coolant temps exceed a certain temperature and the A/C condensor rad needs extra air when the a/c system in running. If you replace both fans with a single one, you'll have to work out how to wire it t come on when either system wants to be cooled. (Usually with a 'lecy fan it comes on at low speed when the a/c system is on, and then on at higher power when the engine wants cooling)
What a load of rubbish.A 1 fan setup will never be as good as a 2 fan front and back setup.As for your suggestion of a brushless motor,that is another load of rubbish,if the brushless motor is of the magnetic variety it will get hot in the radiator area when stood still and when sunlight is on it and it will lose its magnetismThe engine coolant rad needs a fan when coolant temps exceed a certain temperature and the A/C condensor rad needs extra air when the a/c system in running. If you replace both fans with a single one, you'll have to work out how to wire it t come on when either system wants to be cooled. (Usually with a 'lecy fan it comes on at low speed when the a/c system is on, and then on at higher power when the engine wants cooling)
Think before you post
And the man will not control the circuits in an easy way
And it would all need reshrouding and still not be good enough
The best way is to keep it as standard, but you wouldnt suggest that would you
Baaaaaaaaaaaaaaaaaaaaad Info that must be ignored
Edited by Dissapointed1 on Saturday 20th February 15:10
Blaming "the man" is a bit 60's dont you think ?
1 or 2 fans? 2 fans are easyer to control from 2 seperate systems (why most manufacturers use 2 fans) but 2 fans impead airflow IE when the outer (A/C) fan is off it will slow the flow the inner fan is sucking through so (as correctly stated) a single fan can be more efficient.
Replacing a viscouse fan with a leccy one wont really save power, a leccy fan will sap power when on because of the load it places on the alt, a propperly working viscouse fan is simpler and allmost as efficient as a leccy fan.
Thanks everyone, some valid points raised.
Always struck me as a but belts & braces having that big fan attached to the front of the engine whirring away under there but having read into it I quite like the principle.
The main problem with doing a fan conversion is that the car only has a 'high high' level electric switch and I'd really want to run the fan at speed 1 at a 'low high' level, which'd mean having to bodge in another switch somewhere, making up a harness with a relay etc
Seems an OEM viscous coupling is over 120 quid which is more than I was expecting, but having read about cheap faulty fan clutches causing fans to grenade I wouldn't want to risk aftermarket, this engine sees 6,750rpm occasionally.
I opened the aux fan motor. it's a very nice old motor. Everything looks good in there, nice smooth bearings, seems the problem is these detached magnets.
Always struck me as a but belts & braces having that big fan attached to the front of the engine whirring away under there but having read into it I quite like the principle.
The main problem with doing a fan conversion is that the car only has a 'high high' level electric switch and I'd really want to run the fan at speed 1 at a 'low high' level, which'd mean having to bodge in another switch somewhere, making up a harness with a relay etc
Seems an OEM viscous coupling is over 120 quid which is more than I was expecting, but having read about cheap faulty fan clutches causing fans to grenade I wouldn't want to risk aftermarket, this engine sees 6,750rpm occasionally.
I opened the aux fan motor. it's a very nice old motor. Everything looks good in there, nice smooth bearings, seems the problem is these detached magnets.
On my 2.8 (in a Z3) I've removed the viscous And replaced aux fan (the old one had detached magnets). Got a Truktec one (which I believe is OEM manufacturer) unit from ECP for around £120 I believe including the whole shroud. It was for a 325i but fitted the Z3 with some removal of excess plastic that was put there for the 3 series fitment.
Viscous fan removal of very common on these cars. I've had two fans grenade and the viscous clutch unit fail.
Just check the temp switch on the side of the radiator is working well and of course do a full refresh of cooling system (thermostat, pump etc are all service items on these cars by this age). Also get a new radiator cap from BMW, not a pattern part.
I think the 2.5 has a aluminum thermostat housing but if not change that too, the plastic ones do crack...only part of the cooling system I've not changed is the radiator and expansion tank but I'd like to do that this year, they have habit of failing eventually too.
Viscous fan removal of very common on these cars. I've had two fans grenade and the viscous clutch unit fail.
Just check the temp switch on the side of the radiator is working well and of course do a full refresh of cooling system (thermostat, pump etc are all service items on these cars by this age). Also get a new radiator cap from BMW, not a pattern part.
I think the 2.5 has a aluminum thermostat housing but if not change that too, the plastic ones do crack...only part of the cooling system I've not changed is the radiator and expansion tank but I'd like to do that this year, they have habit of failing eventually too.
Clearly a man who's read up on BMW cooling systems then! Best get it all done one time, not piecemeal, saves a lot of hassle and embarrassment. Steam coming out the kidney grilles is never cool..
That's a good price on the clutch.You can refill the viscous units if you are not in a hurry, I think if you google Toyota viscous fan refill it comes up. Whilst I remember it very important the clutch is/was stored the right way up or else it may not work, something about the oil in it. The packaging is marked showing right side up I think.
If you are keeping the viscous unit then I'd suggest getting a brand new plastic fan blade unit and make sure it's not damaged/bent blades when fitting. The plastic gets old causing the grenading. My new one then decided to lose a couple of blades a few months after fitting and apparently could have been due to some blades being weakened when fitting/dropped in transit etc. hard to see how as it's very sturdy but it does turn fast and shift a lot of air so I guess it's plausible.
I got fed up and just ditched it now!
That's a good price on the clutch.You can refill the viscous units if you are not in a hurry, I think if you google Toyota viscous fan refill it comes up. Whilst I remember it very important the clutch is/was stored the right way up or else it may not work, something about the oil in it. The packaging is marked showing right side up I think.
If you are keeping the viscous unit then I'd suggest getting a brand new plastic fan blade unit and make sure it's not damaged/bent blades when fitting. The plastic gets old causing the grenading. My new one then decided to lose a couple of blades a few months after fitting and apparently could have been due to some blades being weakened when fitting/dropped in transit etc. hard to see how as it's very sturdy but it does turn fast and shift a lot of air so I guess it's plausible.
I got fed up and just ditched it now!
I've an old Volvo fan with shroud in the garage, your welcome to it and may be able to get it fit. I'm pretty sure it's a pusher, it certainly a solid thing that shifts a lot of air.
I was going to fit it to a ratty classic with a marginal cooling system, but it's long gone now.
If you're local and want it PM me.
I was going to fit it to a ratty classic with a marginal cooling system, but it's long gone now.
If you're local and want it PM me.
Telling you one more time.This cant be done with a 1 front mounted electric fan layout
The gang are out in force here and they are not even thinking about what I posted
For a 1 fan system everything would need redesigning for your car.The fins in the radiators would need to be different to get the airflow and the shrouds would need to be different
Everyone is overlooking the obvious you need to keep it standard or change everything
Dont be fooled by a majority that dont know much about cooling sytem design
I know it wont work because I have worked on these system designs
Please dont break your engine for this lot
The gang are out in force here and they are not even thinking about what I posted
For a 1 fan system everything would need redesigning for your car.The fins in the radiators would need to be different to get the airflow and the shrouds would need to be different
Everyone is overlooking the obvious you need to keep it standard or change everything
Dont be fooled by a majority that dont know much about cooling sytem design
I know it wont work because I have worked on these system designs
Please dont break your engine for this lot
PositronicRay said:
I've an old Volvo fan with shroud in the garage, your welcome to it and may be able to get it fit. I'm pretty sure it's a pusher, it certainly a solid thing that shifts a lot of air.
I was going to fit it to a ratty classic with a marginal cooling system, but it's long gone now.
If you're local and want it PM me.
Thanks for that, much appreciated. I've actually heard on the BMW5 forum that a Volvo fan is the retrofit of choice. Today I'm going to put that motor back together to see if I can get it working, if that fails...I was going to fit it to a ratty classic with a marginal cooling system, but it's long gone now.
If you're local and want it PM me.
Disappointed1, I appreciate what you're saying, I'm not going to rush into anything; BMW fitted two fans for a reason and I'll most likely stick with this arrangement.
That said I do believe that one high powered electric fan, carefully wired, could act as an effective substitute as Max Torque said.
Max_Torque said:
Dissapointed1 said:
I know it wont work because I have worked on these system designs
really? seems pretty dam unlikely to me, or is this one of your better cooling pack designs:
;-)
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