Doh! silly question time! suck or blow?
Discussion
4.3 precat....swirl tank,expansion tank on crossmember and twin electric fans.....
Hi guys,
Dumb question perhaps! just been for a blast and temp gradualy went up to just on the red after about 8 miles at an average 50mph.....
Fans are cutting in ok
Fan overide switch also fitted
New otter and thermo fitted (leven cool running kit)
Bled system last week
Now the dumb bit....Which way are the fans supposed to turn i.e............
Are they supposed to blow air at the rad from the engine side?
Or suck air through the rad from outside? (this was the way they were turning)!
Swapped wires over so they blow at the rad and on tickover temp is holding just below the 90 line with fans cutting in and out fine
(very confused now)
Thanks for any help in advance
Rob.
Hi guys,
Dumb question perhaps! just been for a blast and temp gradualy went up to just on the red after about 8 miles at an average 50mph.....
Fans are cutting in ok
Fan overide switch also fitted
New otter and thermo fitted (leven cool running kit)
Bled system last week
Now the dumb bit....Which way are the fans supposed to turn i.e............
Are they supposed to blow air at the rad from the engine side?
Or suck air through the rad from outside? (this was the way they were turning)!
Swapped wires over so they blow at the rad and on tickover temp is holding just below the 90 line with fans cutting in and out fine
(very confused now) Thanks for any help in advance
Rob.
Hopefully you're mistaken about which way the fans were running. The fans should move the air through in the same direction that it would take due to the ram air effect i.e. in at the front of the car and out the back into the engine bay. If your fan was running backwards you'd see exactly the symptoms you got, of it overheating with the fans on at moderate speed.
Rather than looking at the direction of rotation of the fans, it's better to feel for the air blast. If they're sucking you won't feel much happening at all. If they're blowing, you'll get a facefull of hot air when you lift the bonnet and when you pass your hand over the back of the fan you'll feel a strong blast.
Usual caution about dangling bits of your anatomy or clothing into moving machinery applies.
Rather than looking at the direction of rotation of the fans, it's better to feel for the air blast. If they're sucking you won't feel much happening at all. If they're blowing, you'll get a facefull of hot air when you lift the bonnet and when you pass your hand over the back of the fan you'll feel a strong blast.
Usual caution about dangling bits of your anatomy or clothing into moving machinery applies.
GreenV8S said:
Hopefully you're mistaken about which way the fans were running. The fans should move the air through in the same direction that it would take due to the ram air effect i.e. in at the front of the car and out the back into the engine bay. If your fan was running backwards you'd see exactly the symptoms you got, of it overheating with the fans on at moderate speed.
Rather than looking at the direction of rotation of the fans, it's better to feel for the air blast. If they're sucking you won't feel much happening at all. If they're blowing, you'll get a facefull of hot air when you lift the bonnet and when you pass your hand over the back of the fan you'll feel a strong blast.
Usual caution about dangling bits of your anatomy or clothing into moving machinery applies.
I don't think he was mistaken. I read it that he said the fans were drawing air through the rad from the outside origonally (which is obviously the correct way). But then swapped the wires to blow air from the engine side out (wrong way, and will fight against the airflow when the car is moving).
Please clear it up for us Rob
David H said:
Hopefully you're mistaken about which way the fans were running. The fans should move the air through in the same direction that it would take due to the ram air effect i.e. in at the front of the car and out the back into the engine bay. If your fan was running backwards you'd see exactly the symptoms you got, of it overheating with the fans on at moderate speed.
Rather than looking at the direction of rotation of the fans, it's better to feel for the air blast. If they're sucking you won't feel much happening at all. If they're blowing, you'll get a facefull of hot air when you lift the bonnet and when you pass your hand over the back of the fan you'll feel a strong blast.
Usual caution about dangling bits of your anatomy or clothing into moving machinery applies.
Correct Dave!
OK so now I'm very peeeeed off!
Thought I had found the solution by making the fans blow from inside out !!
Think the only thing I can do is take it for another blast in this configuration and see what the temp gauge does! or is this a bad idea?
Thanks so far
Rob
I don't think he was mistaken. I read it that he said the fans were drawing air through the rad from the outside origonally (which is obviously the correct way). But then swapped the wires to blow air from the engine side out (wrong way, and will fight against the airflow when the car is moving).
Please clear it up for us Rob
>> Edited by llanelli-rob on Thursday 25th May 20:02
GreenV8S said:
Hopefully you're mistaken about which way the fans were running. The fans should move the air through in the same direction that it would take due to the ram air effect i.e. in at the front of the car and out the back into the engine bay. If your fan was running backwards you'd see exactly the symptoms you got, of it overheating with the fans on at moderate speed.
Rather than looking at the direction of rotation of the fans, it's better to feel for the air blast. If they're sucking you won't feel much happening at all. If they're blowing, you'll get a facefull of hot air when you lift the bonnet and when you pass your hand over the back of the fan you'll feel a strong blast.
Usual caution about dangling bits of your anatomy or clothing into moving machinery applies.
just re read this..................
When I lifted the bonnet I did get a face full of hot air,and holding my hand behind the fans there is copious(good word eh!) amounts of hot air!!(YES A BLAST EVEN!)so does this mean they actually were on blow and I am getting the toatally wrong end of the stick with regard to fan pitches rotation etc etc?
VERY VERY VERY CONFUSED NOW EVEN MORE
>> Edited by llanelli-rob on Thursday 25th May 19:57
>> Edited by llanelli-rob on Thursday 25th May 20:01
>> Edited by llanelli-rob on Thursday 25th May 20:17
Quinny said:
If you got a face full of hot air when lifting the bonnet, I'd say they're turning in the correct direction
Andy.
Think I've got my head around this,if your blowing at the rad your going to get a hot backlash back at you no/yes?
think what greenv8s was saying is correct and my fans were going the wrong way!
come on chaps get your bums off the couch,go and warm your beasts up and lets prove the situation
>> Edited by llanelli-rob on Thursday 25th May 20:59
When you open the bonnet and put your hand near the side of the fan that is accessable ( ie.not the side thats against the rad) it should be blowing be careful not to get anything caught in the moving parts.So the fan sucks air from outside draws it through the rad and into the engine bay.
Hope this helps
Hope this helps
David H said:
Hopefully you're mistaken about which way the fans were running. The fans should move the air through in the same direction that it would take due to the ram air effect i.e. in at the front of the car and out the back into the engine bay. If your fan was running backwards you'd see exactly the symptoms you got, of it overheating with the fans on at moderate speed.
Rather than looking at the direction of rotation of the fans, it's better to feel for the air blast. If they're sucking you won't feel much happening at all. If they're blowing, you'll get a facefull of hot air when you lift the bonnet and when you pass your hand over the back of the fan you'll feel a strong blast.
Usual caution about dangling bits of your anatomy or clothing into moving machinery applies.
I don't think he was mistaken. I read it that he said the fans were drawing air through the rad from the outside origonally (which is obviously the correct way). But then swapped the wires to blow air from the engine side out (wrong way, and will fight against the airflow when the car is moving).
Please clear it up for us Rob
Hows that Knee Dave, YHM
Greenv8s stated......
Rather than looking at the direction of rotation of the fans, it's better to feel for the air blast. If they're sucking you won't feel much happening at all. If they're blowing, you'll get a facefull of hot air when you lift the bonnet and when you pass your hand over the back of the fan you'll feel a strong blast.
...................................................................
I refer you back to this quote Guys......
would someone please be kind enough to put this theory to the test for me tomo and report back the findings here?
I think that whats been stated here is correct and was my exact problem,only a car which has not been giving problems with cooling issues can prove this?
Thanks all
Look forward to hearing back from one of you who has tried it
Green Meanie said:
When you open the bonnet and put your hand near the side of the fan that is accessable ( ie.not the side thats against the rad) it should be blowing be careful not to get anything caught in the moving parts.So the fan sucks air from outside draws it through the rad and into the engine bay.
Hope this helps
Thats the opposite to what greenv8s is saying!
The terminology can be confusing as to whether a fan blows or sucks.
Generally when referring to radiator fans, the term refers to the action upon the radiator.
ie: if the fan pushes air through the radiater its blowing. If the fan draws air through the rad from the other side, its sucking.
in all cases when it comes car rads you want the fan to be putting air into the engine bay, and as the fan is mounted engine side of the rad it needs to suck in this situation.
When you look at the fan blades as mentioned earlier the leading edge of the blade (nearest the rad) need to be be the first part of the blade to make contact with the air during rotaion in order to draw air through rad and into the engine bay.
Hope that finally clears the confusion up :-)
>> Edited by bluebottle on Thursday 25th May 22:22
Generally when referring to radiator fans, the term refers to the action upon the radiator.
ie: if the fan pushes air through the radiater its blowing. If the fan draws air through the rad from the other side, its sucking.
in all cases when it comes car rads you want the fan to be putting air into the engine bay, and as the fan is mounted engine side of the rad it needs to suck in this situation.
When you look at the fan blades as mentioned earlier the leading edge of the blade (nearest the rad) need to be be the first part of the blade to make contact with the air during rotaion in order to draw air through rad and into the engine bay.
Hope that finally clears the confusion up :-)
>> Edited by bluebottle on Thursday 25th May 22:22
llanelli-rob said:
When you open the bonnet and put your hand near the side of the fan that is accessable ( ie.not the side thats against the rad) it should be blowing be careful not to get anything caught in the moving parts.So the fan sucks air from outside draws it through the rad and into the engine bay.
Hope this helps
Thats the opposite to what greenv8s is saying!
This is correct though.
If the fans blow in to the engine bay they are drawing air through the rad from the outside world (the same direction as when the car is moving) in to the engine bay.
If the fans draw air from the engine bay and blow it through the rad and to the outside world it be fighting against the airflow of the incoming air from the car moving. The fan will also not work well in that direction, and the air from the engine bay will not be as cool as the outside abient temp.
Your fans were wired fine to start with if you got a blast of hot air in the face when you put your head in to the engine bay.
Hope this helps
>> Edited by David H on Thursday 25th May 22:48
so thats why they call it a BJ 
bluebottle said:
The terminology can be confusing as to whether a fan blows or sucks.
Generally when referring to radiator fans, the term refers to the action upon the radiator.
ie: if the fan pushes air through the radiater its blowing. If the fan draws air through the rad from the other side, its sucking.
in all cases when it comes car rads you want the fan to be putting air into the engine bay, and as the fan is mounted engine side of the rad it needs to suck in this situation.
When you look at the fan blades as mentioned earlier the leading edge of the blade (nearest the rad) need to be be the first part of the blade to make contact with the air during rotaion in order to draw air through rad and into the engine bay
Hope that finally clears the confusion up :-)
>> Edited by bluebottle on Thursday 25th May 22:22
Right then sorted,
By this my fans were going the right way,but begs the question why do I have cooling issues?
>> Edited by llanelli-rob on Thursday 25th May 22:34
Rob,
Your first post state that the the fans were cutting in and out on tickover which would indikate theat the otter switch is working fine and the temp is being pulled down ok. You mention an aftermarket thermal cooling kit, does this has one or two temp dials on it?
also, what condition is the rad in ie how old is it and is there ANY damage to the fins (they only need the slightest obstruction for them to lose perfomance)?
Your first post state that the the fans were cutting in and out on tickover which would indikate theat the otter switch is working fine and the temp is being pulled down ok. You mention an aftermarket thermal cooling kit, does this has one or two temp dials on it?
also, what condition is the rad in ie how old is it and is there ANY damage to the fins (they only need the slightest obstruction for them to lose perfomance)?
llanelli-rob said:
When you open the bonnet and put your hand near the side of the fan that is accessable ( ie.not the side thats against the rad) it should be blowing be careful not to get anything caught in the moving parts. So the fan sucks air from outside draws it through the rad and into the engine bay.
Hope this helps
Thats the opposite to what greenv8s is saying!
No, that's exactly the same as I was saying.
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