Farmer_Terry Posted July 5, 2008 Share Posted July 5, 2008 The engine was overheating yesterday, and further investigation revealed that, when the car was stationary with the fan running, hot air was being blown out of the front of the car. I can’t imaging a set of circumstances in which this would be correct – particularly yesterday as we were doing a drifting day at Oulton (absolutely fabulous fun 😬 😬 😬). Most of the day was spent in 2nd gear – which meant that the fan was pushing the air out of the front of the car at about the same speed that the car was going forward – so absolutely no air through the radiator at all. Result – overheating until we disconnected the fan. We recently had the alternator changed and the reverse direction appears to be associated with this so my questions are:- 1. Is it possible that the electrical guy simply connected the fan up the wrong way round? If so, we should be able to cure the problem by reversing the connections. 2. If not – how has this happened, and how can we fix it? All help gratefully accepted as usual. Farmer Terry (and his car) Link to comment Share on other sites More sharing options...
CageyH Posted July 5, 2008 Share Posted July 5, 2008 1. Yes and yes. Only dead fish go with the flow....! Link to comment Share on other sites More sharing options...
Jorgen Posted July 5, 2008 Share Posted July 5, 2008 Just disconnect the wires and re-connect the other way arond then you shuold be good to go drifting again Link to comment Share on other sites More sharing options...
Don Cook Posted July 5, 2008 Share Posted July 5, 2008 It depends on the type of motor. If it’s a permanent magnet type then reversing the wires will reverse the rotation. If on the other hand it has field coils it’ll turn the same way whichever way the power is connected. If it’s the second then you either need a different motor or you could open it up and reverse the wires to the carbon brushes. Link to comment Share on other sites More sharing options...
Don Cook Posted July 5, 2008 Share Posted July 5, 2008 Or get a different fan Link to comment Share on other sites More sharing options...
Farmer_Terry Posted July 5, 2008 Author Share Posted July 5, 2008 Don - I don't think it can be a field coil type or the rotation would have been this way for ever, and this is a new phenominon. I will try reversing the wires - at least I can stop worrying about damaging something - but I won't know whether it's worked until I run it up to temperature. Thanks everyone for the advice, and take a quick look here for some photos of a Caterham being driven sideways (delberately). *thumbup* Farmer Terry (and his car) Link to comment Share on other sites More sharing options...
Johnty Lyons Posted July 6, 2008 Share Posted July 6, 2008 but I won't know whether it's worked until I run it up to temperature. If its switched by a rad switch just change wires as you suggest and dis the sw wires and join them together Fan will run jj N.I. L7C AR 🙆🏻 Membership No.3927. 240BHP 1900cc K Series 40th Anniversary Link to comment Share on other sites More sharing options...
Farmer_Terry Posted July 6, 2008 Author Share Posted July 6, 2008 Thanks for the suggestion Johnty. I will give that a try - but we are now away for a few days, so not till we get back. Thanks again everyone. Farmer Terry (and his car) Link to comment Share on other sites More sharing options...
Graham King Posted July 6, 2008 Share Posted July 6, 2008 Is this not just normal operation? Not sure what car this is, but on a K-Series with radiator mounted behind rad, the air is blown forward through the rad (i.e. out the front of the car). The fan is designed to cool the car when stationary not whilst moving. Even if the fan could be made to rotate in the other direction I doubt the blade shape would be right to draw air back through the radiator. In the circumstances that you describe I can see disconnecting the fan would have helped but I don't think reversing the wiring is the right solution. Others usually know better than me but certainly on my K-Series it operates exactly as you describe. Graham. R7 GPK Superlight #85 Link to comment Share on other sites More sharing options...
Johnty Lyons Posted July 6, 2008 Share Posted July 6, 2008 It does what?? Never heard of that if K fans are supposed to push air back through the rad I'm missing something. This Club is amazing You learn something every day. jj N.I. L7C AR 🙆🏻 Membership No.3927. 240BHP 1900cc K Series 40th Anniversary Link to comment Share on other sites More sharing options...
Englishmaninwales Posted July 6, 2008 Share Posted July 6, 2008 but on a K-Series with radiator mounted behind rad, the air is blown forward through the rad (i.e. out the front of the car). Opposite way around on mine Malcolm Link to comment Share on other sites More sharing options...
Englishmaninwales Posted July 6, 2008 Share Posted July 6, 2008 Must type faster 😳 Link to comment Share on other sites More sharing options...
Colin Mill Posted July 6, 2008 Share Posted July 6, 2008 I would have thought that having the fan blow air forward against the natural flow was not a very good idea. There would be a steady driving speed where the fan and the forward motion of the car would tend to cancel out leading to an overheating situation. Also, at high speed I would have thought the airflow through the rad could stall the fan or even drive it backwards leading to a very high current through the fan motor - possibly burning the motor out. Link to comment Share on other sites More sharing options...
Johnty Lyons Posted July 6, 2008 Share Posted July 6, 2008 There are two distinct fans on Ks a high capacity which bolts to the front of the rad and assists the normal movement of air by pushing it through the rad and the standard one which bolts behind and assists by sucking through the rad. It could be conceivably possible to mix them up and get the result mentioned above BUT i've never heard of anyone doing so. 😶🌫️ jj N.I. L7C AR 🙆🏻 Membership No.3927. 240BHP 1900cc K Series 40th Anniversary Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted July 6, 2008 Share Posted July 6, 2008 Fan must move the air through the rad from front to rear of car !!!!!! Graham - time to reverse your fan wires - didn't they teach you anything at Riddlesdown ???? 😬 7 related photos Edited by - Stationary M25 Traveller on 6 Jul 2008 23:47:13 Link to comment Share on other sites More sharing options...
henry21p Posted July 7, 2008 Share Posted July 7, 2008 The fan must either pull or push air from OUTSIDE the car through the rad - it's cool air. Fan is blowing the wrong way. Link to comment Share on other sites More sharing options...
Colin Mill Posted July 7, 2008 Share Posted July 7, 2008 An easy way of checking if the fan is running backwards is to look at the camber of the blades. If, looking at the fan from inside the engine compartment, the side of the blades facing you are concave then the fan must be running backwards as the camber being that way around shows that the fan was designed to pull air through the rad into the engine compartment. Conversely, if you are looking at the convex side of the blades then the fan was designed to be in front of the rad blowing air through the rad. (In short - convex side = input to fan. concave side = output of fan) Link to comment Share on other sites More sharing options...
Graham King Posted July 7, 2008 Share Posted July 7, 2008 Seem to have started a bit of a storm here. I will have to check the rad and fan, but just to be clear. I have just replaced the standard CC rad and fan with a Radtec with upgraded fan. The fan is rear mounted (i.e. behind rad in between rad and engine). Both the previous fan and the new one blow air through the rad towards front of car (at least I can feel air flow in front of Rad when fan is running). I haven't looked at the profile of the fan blades yet to see what Colin describes but can do later. SM25T, obviously didn't teach me enough about electronics and physics 😬 Will report back later. Graham. R7 GPK Superlight #85 Link to comment Share on other sites More sharing options...
Colin Mill Posted July 7, 2008 Share Posted July 7, 2008 SM25T, obviously didn't teach me enough about electronics and physics Oh - lets not start that one again 😬 You may be surprised - I thought the fan on my daughter's Cinquecento (don't laugh) was running backwards because air seemed to be blown out of the front but it was actually going the right way (though the rad was rather blocked up so may have had something to do with the illusion) Edited by - Colin Mill on 7 Jul 2008 11:11:25 Link to comment Share on other sites More sharing options...
Johnty Lyons Posted July 7, 2008 Share Posted July 7, 2008 Both the previous fan and the new one blow air through the rad towards front of car (at least I can feel air flow in front of Rad when fan is running). I refuse to believe this This is a wind up it must be jj N.I. L7C AR 🙆🏻 Membership No.3927. 240BHP 1900cc K Series 40th Anniversary Link to comment Share on other sites More sharing options...
CageyH Posted July 7, 2008 Share Posted July 7, 2008 I thought there was often an arrow to show the intended direction of airflow on a fan. If the fan did push air through, would would happen during slow running, say in slow moving traffic for example? The car would overheat, as you may end up with effectively nor air flow... Only dead fish go with the flow....! Link to comment Share on other sites More sharing options...
FTH Posted July 8, 2008 Share Posted July 8, 2008 Its better for airflow to be through the front of the car in stationary traffic otherwise youre sucking in hot exhaust gases from the car in front. (runs off cackling) Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted July 8, 2008 Share Posted July 8, 2008 noooooooooooooooooooooooooooooooooooooooooooooooooooooooo 😔 7 related photos Link to comment Share on other sites More sharing options...
henry21p Posted July 8, 2008 Share Posted July 8, 2008 gases from the front are GUARANTEED to be cooler than engine bay temperatures!!!! Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted July 8, 2008 Share Posted July 8, 2008 I think ... runs off cackling ... was the clue there !! Naughty mischevious FTH 7 related photos Link to comment Share on other sites More sharing options...
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