Here's a dumb question, I was asked & realised I didn't know the answer.do radiator fans normally mounted behind the radiator blow air towards the radiator or suck air to aid flow through.crikey how ignorant can you be after all these years.
johnf_456,
Apr 25, 5:06pm
Suck it through, otherwise you working against the wind while moving. Aka front to back
neville48,
Apr 25, 5:13pm
machines like bulldozers etc,loaders and cranes etc all blow through the radiator but cars and trux etc suck through the radiator.hope this confuses the hell out of things for you.
morrisman1,
Apr 25, 5:14pm
depends on the car and if they can fit a fan behind the radiator. Will mostly be dependent on availability of space
petermcg,
Apr 25, 5:26pm
Yes and if you take it off and turn it round it still blows the same way
neville48,
Apr 25, 8:51pm
Or.sucks the same way.Ha.
74nova,
Apr 25, 9:28pm
Best to mount the fan from behind and having it sucking, so the front of the radiator is unobstructed.
jjc09,
Apr 25, 9:55pm
Also it can be wired up i reverse to blow or suck
berg,
Apr 26, 5:38am
Lol. I was dealing with a Subaru that had an overheating problem when sitting in traffic. Took a wee bit to work out thet the owner had replaced the radiator fan but had put it on the wrong way round so it was blowing hot air back through the radiator. Spin the fan round and it all settled down.
pfemstn,
Apr 26, 6:01am
fan on car always sucks! if rad faces forward! and fan is behind.if you move a fan from in front,where it blows,to rear you must reverse the blades, and dont tell me a classic Mini is different, cause i know. but the rad is to the sde and it blows into the guard area!
taipan4,
Apr 26, 6:58am
no it does not, turning the fan around does not do it
pdc1,
Apr 26, 7:34am
wording confusing! If you turn the blade over - it still moves the air the same way. You would have to reverse the rotation to get the air to move the opposite way.
and to get back to the original question - it depends on the application.
socram,
Apr 26, 7:54am
Depends on the application indeed.
As per earlier post, on slow moving vehicles such as bulldozers, you are not fighting the air resistanec from going forwards at high speed - or any speed and no doubt blowing the dust out of the radiator makes sense. There is insufficient cooling air generated from going forwards (or backwards.)
For most cars, the fan does absolutely nothing at high speed which why engine driven fans are nothing more than a power sapper.Putting a fan behind the radiator allows the maximum amount of radiator exposure to the cooling air.Once on the move, it is pointless having a rear mounted fan push air forwards, but if very slow moving or stationary it is fine.Once the engine has cooled, the fan switches off anyway.
Reversing polarity only works if the fan blades are also reversed.
Dedicated race cars do not have fans.
74nova,
Apr 26, 12:34pm
Wrong. The polarity reversing is the only way to change the direction. reversing the fan blade does not change the direction of flow, it will still flow the same way.
bigfatmat1,
Apr 26, 12:47pm
Last week when I fitted a 'new' fan the instructions said turn the blade round. which in my application worked fine.
neville48,
Apr 26, 3:40pm
Last time i read the instructions that said turn the fan around to face the other way,i did this and could not see the car,it was behind me so i turned back and woopee.there it was so i had someone else do the job.too confusing for me huh!
pdc1,
Apr 26, 3:50pm
of course it will (probaby) be more efficient one way than the other, therefore if you change the direction of fan i.e. reverse polarity, you should turn the blade over too. However turning the blade over by itself doesn't change the direction of the flow.
shuddupowh,
Apr 26, 4:55pm
I never knew that. But how come if its sucking the air thru the radiator, it doesnt blow all over the engine like an inside house fan would! And my E30 has an engine driven fan which spins faster the higher the revs - so when idling it just spins normal and at high speeds it spins faster - kind of defeating the purpose cos when idling it will get hotter. With electric fans such as todays fans, how long should the car be running before it starts! For example, as soon as the temp gauge goes up or when its near 1/4 - 1/2 hot!
bigfatmat1,
Apr 26, 5:19pm
lol pdc1 you should not reverse polarity in motors btw all though it may work for ya in reverse polarity. What happens when the earth brush is not isolated and the case is metal it will mean a live case that isn't a good idea at all. On your theory of reversing blades does not work please do not ever get a job working on planes cause the plane would have to go in reverse to land.
electro2000,
Apr 26, 5:32pm
wtfreversing the pitchie turning the blade around reverses the air flow simple.propeller planes like metro liners etc reverse the propeller pitch after touch down to reverse the thrust.Ships do not reverse the direction of the shaft these days to go back wards they just reverse the pitch to go backward
socram,
Apr 27, 6:52am
You are forgetting the shape of the fan blades are designed to aid the flow, so not turning the blades simple means that they are not as efficient. I didnt say that reversing the blades would reverse the flow, I said that you needed to do both.
johnf_456,
Apr 27, 6:58am
bad advice
74nova,
Apr 27, 7:05am
Yes thats true, I didn't think about that. I've seen fans where the blades are formed the same so changing the fan blade around does nothing.
johnf_456,
Apr 27, 7:13am
Too tired to type it all and explain.
smac,
Apr 27, 7:17am
pfft.whatever
All after-market auto fans I have ever seen come with instructions on direction, flow etc. In those instructions they explain how you should reverse the polarity to reverse the fan direction, and how you should also flip the fan over so the aerofoil blades are facing the right way.
SO again, how was the quoted piece above bad advice!
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