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Car Forum / BMW Cars / July 2005A funny thing happened on the way thru an oil change
I was changing the oil in my car, and while waiting for the dripping to stop, I looked around at all of the stuff there is to look at under a car, and wondered what all of the plastic parts were that were laying around near the bottom of the radiator. It hit me that the fan was gone. The plastic parts were the remants of the fan blades. The fan was completely gone. I had no idea from the guages or anything else that the fan wasn't with me anymore. Indeed, I have been wondering if the motor runs too cold in the morning because I have seen the guage take forever to reach the mid point of the scale, then over the course of a mile or so on the freeway, the needle will drop to the blue and slowly rise back to the mid point again. I was guessing that the tstat might be stuck open, but I had no idea that the fan wasn't there. I would expect the engine to get very hot, at least is slow moving traffic on a hot day, if the fan was not working, but there was no indication whatsoever. The fan is very easy to replace, one reverse-threaded nut on the fan clutch and three small allen screws. That's it. I just wanted to share ... > I was changing the oil in my car, and while waiting for the dripping to > stop, I looked around at all of the stuff there is to look at under a car, [quoted text clipped - 16 lines] > > I just wanted to share ... That is a funny one, Jeff. But I suppose one would never notice their lack of a fan unless, or until, they get stuck in traffic and need to stand stationary for a while. Which brings me to another thought... why do we need fans that run directly off the engine, increasing and decreasing with engine speed, when in all reality, the biggest need for additional air flow thru the radiator will be at the lowest engine speed, and the least need for the fan will be at higher rpm when we are making good speed? Seems like an intelligently controlled electric fan would be a better design, no? -Fred W >> I was changing the oil in my car, and while waiting for the dripping to >> stop, I looked around at all of the stuff there is to look at under a [quoted text clipped - 36 lines] > Seems like an intelligently controlled electric fan would be a better > design, no? Years ago, I had a 1971 Ford truck. the fan was bolted straight to the water pump. It didn't matter much since the engine didn't go much past 4000 RPM anyways.. However, in the newer cars. they have a fluid clutch, so when its cooler, the fan almost completely slips. As it gets hotter, the clutch will engage more and more until its fully locked. This has worked for many years, but just as you say, its not the most efficient way of doing it. The fan usually robs about 15-20 HP. So removing the mechanical fan and putting in an electric one with a thermostat is better, but also costs a fraction more. This is most common on front steel drive cars with the transverse mounted engines. > > I was changing the oil in my car, and while waiting for the dripping to > > stop, I looked around at all of the stuff there is to look at under a car, [quoted text clipped - 20 lines] > lack of a fan unless, or until, they get stuck in traffic and need to > stand stationary for a while. That's what I woulda thunk too. But, I'm in Southern California and we have already been well into the 90s and I've been stopped in traffic with the A/C on high. > Which brings me to another thought... why do we need fans that run > directly off the engine, increasing and decreasing with engine speed, [quoted text clipped - 4 lines] > Seems like an intelligently controlled electric fan would be a better > design, no? Anything that won't break would be an improvement. It isn't the engine speed that dictates the air flow, it's the ground speed. If the car is moving, there is air flow through the radiator, and if the A/C is on, there is an electric fan that kicks in, maybe this fan is enough ... Hmmm, Strictly speaking, no. It's the air speed only. However, we won't quibble for a motor car... :-) For an aircraft it really matters whether there is a headwind or tailwind. The difference between ground speed and air speed can easily reach 50 mph or more. DAS For direct contact replace nospam with schmetterling --- [...] > It isn't the engine speed that dictates the air flow, it's the ground > speed. [...] ----- Original Message ----- From: "Malt_Hound" <Malt_Hound@*spam*yahoo.com> Newsgroups: alt.autos.bmw Sent: Wednesday, July 06, 2005 2:16 AM Subject: Re: A funny thing happened on the way thru an oil change snip > Which brings me to another thought... why do we need fans that run > directly off the engine, increasing and decreasing with engine speed, when [quoted text clipped - 6 lines] > > -Fred W BMW fans are viscously coupled - engine cold - fan slips ; engine hot fan spins. Electric fan should cut in if engine get too hot (e.g. in traffic), but represent a potentially disastrous failure mode if relied on completely. I should try and find out why the fan blades broke - any sign of the remains of the neighbour's cat that hid under the bonnet. > ----- Original Message ----- > From: "Malt_Hound" <Malt_Hound@*spam*yahoo.com> [quoted text clipped - 23 lines] > I should try and find out why the fan blades broke - any sign of the remains > of the neighbour's cat that hid under the bonnet. No signs of the cat. Well, there wasn't any fur on the plastic parts that I found. I did have some service recently, and I found that the fan shroud wasn't fully clipped into place. I don't know that it came unclipped as a result of the fan coming apart, or caused the fan to come apart. The shroud is in good shape considering the other distruction in the area. > ----- Original Message ----- > From: "Malt_Hound" <Malt_Hound@*spam*yahoo.com> [quoted text clipped - 23 lines] > I should try and find out why the fan blades broke - any sign of the remains > of the neighbour's cat that hid under the bonnet. Yeah, but my SAABs with 4 cylinder transverse engines all had electric fans, and they were pretty darn reliable. They worked simply on the thermostatic switch that measured the coolant temp in the radiator. So long as the coolant in there was OK then the cooling system should be able to regulate properly via the regular coolant thermostat. The nice thing about that design is that when you are traveling at a decent speed (45mph+) the forced airflow through the radiator is more than the little fan can create so it does not need to run. OTOH, there is a 2 speed control on the SAAB fan so that with the AC on, or if the temp gets above a secondary threshold the fan goes into warp drive. This really seems to be a more intelligent design to me... -Fred W > Yeah, but my SAABs with 4 cylinder transverse engines all had electric > fans, and they were pretty darn reliable. With a transverse engine and a front mounted rad it would be difficult to have an engine driven fan...  Signature*If at first you don't succeed, redefine success. Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound. > > Yeah, but my SAABs with 4 cylinder transverse engines all had electric > > fans, and they were pretty darn reliable. > > With a transverse engine and a front mounted rad it would be difficult to > have an engine driven fan... It would be difficult to have an engine driven fan that was between the engine and the radiator. If one didn't care where the fan was relative to where the radiator was, then it would be a relatively simple matter to have an engine driven fan. It wouldn't be a very useful fan though. > > With a transverse engine and a front mounted rad it would be difficult > > to have an engine driven fan... > It would be difficult to have an engine driven fan that was between the > engine and the radiator. Not so - the original Mini did just this. With a side mounted rad... > If one didn't care where the fan was relative > to where the radiator was, then it would be a relatively simple matter > to have an engine driven fan. It wouldn't be a very useful fan though. Signature*A bartender is just a pharmacist with a limited inventory * Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound. > Which brings me to another thought... why do we need fans that run > directly off the engine, increasing and decreasing with engine speed, > when in all reality, the biggest need for additional air flow thru the > radiator will be at the lowest engine speed, and the least need for the > fan will be at higher rpm when we are making good speed? > Seems like an intelligently controlled electric fan would be a better > design, no? Or a progressively driven mechanical one which idles when not needed... Signature*I believe five out of four people have trouble with fractions. * Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound. >> Which brings me to another thought... why do we need fans that run >> directly off the engine, increasing and decreasing with engine speed, [quoted text clipped - 6 lines] > > Or a progressively driven mechanical one which idles when not needed... The latest hi-tech zenith of efficiency is the Viscotronic fan. This has an engine management controlled variable speed viscous fan. It is an amazing piece of kit. I happen to have a bit of experience with an application where a diagnostic laptop can be linked to the vehicle and the speed of the fan can be infinitely varied within reason by means of mouse on slider. It so happens that I have two near identical vehicles except that one has a simple viscous coupled fan and the other having the latest viscotronic unit and the reduction of noise from the latter is very noticeable. With the same fan blades it is probable that this equates to a significant gaining of horsepower or reduction in fuel consumption. Huw > The latest hi-tech zenith of efficiency is the Viscotronic fan. This has an > engine management controlled variable speed viscous fan. It is an amazing [quoted text clipped - 6 lines] > blades it is probable that this equates to a significant gaining of > horsepower or reduction in fuel consumption. Cool beans... That is the exact bit of trivial detail that had me asking the question in the first place. On my Z3, once the engine reaches full temperature, the fan noise at normal engine rpm (above 3000 rpm) is annoying, even though I'm tooling along at a high enough rate of speed so that the need for the fan is negligible. -Fred W PS - I'm just back from 2 weeks R&R in northern Maine, in case anyone missed me (or hoped I had dropped off the planet...) >> In article <taudnVwGx8p5rVbfRVn-gA@adelphia.com>, >> Malt_Hound <Malt_Hound@*spam*yahoo.com> wrote: [quoted text clipped - 10 lines] >> Or a progressively driven mechanical one which idles when not >> needed... err, but it DOES do just that..... > >>> Seems like an intelligently controlled electric fan would be a > >>> better design, no? > >> > >> Or a progressively driven mechanical one which idles when not > >> needed... > err, but it DOES do just that..... ;-) Signature*Those who live by the sword get shot by those who don't. Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound. >>>In article <taudnVwGx8p5rVbfRVn-gA@adelphia.com>, >>> Malt_Hound <Malt_Hound@*spam*yahoo.com> wrote: [quoted text clipped - 13 lines] > > err, but it DOES do just that..... No, it doesn't. The fan runs even when the car is moving forward at a high speed forcing more air through the radiator than the fan ever could. -Fred W > Which brings me to another thought... why do we need fans that run > directly off the engine, increasing and decreasing with engine speed, when [quoted text clipped - 4 lines] > Seems like an intelligently controlled electric fan would be a better > design, no? I am pretty certain the new era of BMW's have electric radiator fans. I thought I read somewhere that is one of the means they used to lower engine loading to increase power yet maintain fuel efficiency (apparently better battery capabilities mean less load without the fan belt, but also no increased load for the alternator). The fan and fan speed are driven by signals from the engine controller. I also think they might have electric water pumps for the same reason. And I know both my E39's had at least some semblance of an electric fan because it would run long after the engine shut down on hot days when the AC had been used. >> Which brings me to another thought... why do we need fans that run >> directly off the engine, increasing and decreasing with engine speed, when [quoted text clipped - 16 lines] >because it would run long after the engine shut down on hot days when the AC >had been used. That's the auxillary electrical fan for cooling AC condenser. The main fan is mechanical with a viscous clutch. Check out http://www.realoem.com/bmw/partgrp.do?model=DD51&mospid=47544&hg=11&fg=35 for the main fan (located between the radiator and engine) and http://www.realoem.com/bmw/partgrp.do?model=DD51&mospid=47544&hg=64&fg=55 for the AC fan (located in front of the radiator). Signature/"\ Jan Kalin (male, preferred languages: Slovene, English) \ / http://charm.zag.si/eng/, email: "name dot surname AT zag dot si" X ASCII ribbon campaign against HTML in mail and postings. / \ I'm a .signature virus. Copy me to help me spread. >>> Which brings me to another thought... why do we need fans that run >>> directly off the engine, increasing and decreasing with engine speed, [quoted text clipped - 28 lines] > http://www.realoem.com/bmw/partgrp.do?model=DD51&mospid=47544&hg=64&fg=55 > for the AC fan (located in front of the radiator). Thanks. I was wrong on the new cars' water pump too. The site clearly shows the water pump and alternator run from the same belt. > Thanks. I was wrong on the new cars' water pump too. The site clearly > shows the water pump and alternator run from the same belt. Thing is if you're going to drive an alternator from a belt and then use that electricity to drive a waterpump and fan, you might as well drive the waterpump and fan directly. When we get high voltage alternators that are part of the flywheel so no friction from the drive, things might be different. I dunno how much power a waterpump devours, and whether the ability to vary its output independant of engine speed would be useful or not, though. But I'd say viscous coupled fans are pretty efficient - and rather longer lived than the average electric fan - if the aux one on the E39 is anything to go by. ;-) Signature*Certain frogs can be frozen solid, then thawed, and survive * Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound. >>Thanks. I was wrong on the new cars' water pump too. The site clearly >>shows the water pump and alternator run from the same belt. [quoted text clipped - 8 lines] > rather longer lived than the average electric fan - if the aux one on the > E39 is anything to go by. ;-) Well, sort of... My thought was with electric auxiliaries, you can turn them on and off with intelligent controls rather than just having them run all the time that the engine is running. For instance, running a water pump full time, or the fan full time, even though the engine may not need them. I also recall reading somewhere that a pusher fan is more efficient than a puller type such as one driven off the engine. -Fred W >>>Thanks. I was wrong on the new cars' water pump too. The site clearly >>>shows the water pump and alternator run from the same belt. [quoted text clipped - 21 lines] > > -Fred W One idea I like with the electric fan and water pump is the car can then continue to run them after the engine is off until the engine temp gets below a set temp. >> Thanks. I was wrong on the new cars' water pump too. The site clearly >> shows the water pump and alternator run from the same belt. > > Thing is if you're going to drive an alternator from a belt and then use > that electricity to drive a waterpump and fan, you might as well drive the > waterpump and fan directly. Well maybe the water pump. The heat generated inside the engine is generally proportional to rev's and a bit dependent on load, so the flow of cooling water should vary with engine speed, which it will do if the pump is directly driven. The operation of the fan depends on the amount of heat generated, but also on how difficult it is to get rid of. Factors such as ambient temprature, current block temperature, speed of the car, wind, is it raining, use of the in car heater etc. all affect how fast the fan will need to go to dispose of the suprlus heat. > When we get high voltage alternators that are > part of the flywheel so no friction from the drive, things might be [quoted text clipped - 3 lines] > rather longer lived than the average electric fan - if the aux one on the > E39 is anything to go by. ;-) > > Thing is if you're going to drive an alternator from a belt and then > > use that electricity to drive a waterpump and fan, you might as well > > drive the waterpump and fan directly. > Well maybe the water pump. The heat generated inside the engine is > generally proportional to rev's and a bit dependent on load, so the flow > of cooling water should vary with engine speed, which it will do if the > pump is directly driven. > The operation of the fan depends on the amount of heat generated, but > also on how difficult it is to get rid of. Factors such as ambient > temprature, current block temperature, speed of the car, wind, is it > raining, use of the in car heater etc. all affect how fast the fan will > need to go to dispose of the suprlus heat. Hence the temperature sensitive viscous coupling? And I'd suggest a BMW one is more powerful when locked up than any electric one. Signature*Warning: Dates in Calendar are closer than they appear. Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound. >>> Thanks. I was wrong on the new cars' water pump too. The site clearly >>> shows the water pump and alternator run from the same belt. [quoted text clipped - 8 lines] > of cooling water should vary with engine speed, which it will do if the > pump is directly driven. That is true and has worked for years, but given the need to enhance power while lowering fuel consumption, an electric driven water pump and radiator fan makes a lot of sense. I agree with Fred on this. I found the article I was lloking for, and BMW is using an electric water pump (engine cooling, not just heater core flow) in the E90...and their results indicate the savings from the pump compared to the increased load on the alternator, is well worth the change. great, another thing that can go wrong and cause overheating - an electric water pump. is it so much better than the aluminum one in the newer E36 ? >>and BMW is using an electric water pump (engine cooling, not just heater core flow) in the E90... >>>> Which brings me to another thought... why do we need fans that run >>>> directly off the engine, increasing and decreasing with engine speed, [quoted text clipped - 32 lines] > Thanks. I was wrong on the new cars' water pump too. The site clearly > shows the water pump and alternator run from the same belt. Diesel versions have an extra electric water pump which continues to pump coolant around the turbocharger bearing and cylinder head area after shut-down. Huw I had a friend with a large car in times past. It was some kind of Buick and had a huge fan and a large space between the fan and the radiator, with a giant cowling coupling the radiator to the fan. Well, he parked it one day at another friends house, a cold autumn day and we went inside to suck back on some wobbly pops. When we went out and started the car, the most horrible whining sound came from under the hood, we stopped the engine and a cat ran out from underneath the car. The cat was not injured, just scared to death. It had sat in close to the radiator to get warm. After that experience, any time a car pulled up in the driveway, the cat would run in the other direction. > I was changing the oil in my car, and while waiting for the dripping to > stop, I looked around at all of the stuff there is to look at under a car, [quoted text clipped - 16 lines] > > I just wanted to share ... |
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