iggy Posted December 23, 2012 Share Posted December 23, 2012 ive got a couple of 10" 12v rad fans and a relay id like to fit to my mk2 2500, all i need is a fan switch to fit into the thermostat housing, what size and type of threads are the temperature sender and return pipe conections? also i was thinking of a 93 deg c to 86 deg c temperature range for the switch is this ok? any advice appreciated thanks Quote Link to comment Share on other sites More sharing options...
Van Posted December 23, 2012 Share Posted December 23, 2012 Previous owner of my car 2.5PI fitted an early Fiesta rad fan switch to my 2.5PI by drilling a hole in the top of the thermostat housing and fixing it in with a "cold weld" type compound. Worked very well but I don't know the temp range and I no longer have the car.My GT6 has a VW rad and a Peugeot fan switch 84/79 degC in the bottom. Thread is the same for these 2 makes - M22x1.5, same for a lot of modern cars, but will not fit directly anywhere in the Triumph. If you put the switch at the top you will want to go a few degrees hotter.I used this site to compare:http://partfinder.smpeurope.com/index.html?p=155&typeid=42&recordset=209&value=42 Quote Link to comment Share on other sites More sharing options...
iggy Posted December 23, 2012 Author Share Posted December 23, 2012 thanks van intermotor do have a very good selection of fan switchs, Quote Link to comment Share on other sites More sharing options...
GT6 M Posted December 25, 2012 Share Posted December 25, 2012 Just my way of thinking, I would wire in an over ride switch.mine is this way, as I put fan on when ever I come to standing traffic,even if enginge temp is still way doon,reasoning / practical logik, is that the fan shifts the under bonnet heat,so no affects me idleas the ex gives off alott of heat.and heat can cause all sorts of probs on our cars.maybe some thing to ponder on,!!M Quote Link to comment Share on other sites More sharing options...
John Bonnett Posted December 25, 2012 Share Posted December 25, 2012 796 wrote:Just my way of thinking, I would wire in an over ride switch.mine is this way, as I put fan on when ever I come to standing traffic,even if enginge temp is still way doon,reasoning / practical logik, is that the fan shifts the under bonnet heat,so no affects me idleas the ex gives off alott of heat.and heat can cause all sorts of probs on our cars.maybe some thing to ponder on,!!MI totally agree with you Marcus. I too have an override switch and and like you switch it on as soon as stationary to shift the air.One thing that does puzzle me is that I too have a Golf radiator with a Peugeot two temperature switch fitted bottom left but my switch operates at 97 and 103. If I had one that operated in the low 80s it would be on all the time. Or would it? Perhaps not. Engine runs at the mid point but I've no idea what the temperature is at the point where the switch is mounted. So perhaps a low temperature switch would be okay. The temperature climbs fairly quickly once stationary and it is not long before the fan cuts in. Quote Link to comment Share on other sites More sharing options...
Van Posted December 25, 2012 Share Posted December 25, 2012 I also have the 2-speed Pug radiator fan switch. The low speed is 84/79 and the high speed is 88/83. I have wired the fan relay into the lower temp side of the switch. In very hot weather the fan comes on with the temp gauge about 1/2 way up. In very cold weather the fan comes on with the temp gauge about 3/4 way up (the difference is because the temp gauge measures the temp at the top of the rad, and there is a bigger difference in temp across the rad in colder weather). I have re-wired the interior light switch in the dash so it is now an override switch for the fan. One of the advantages of a 2-speed switch is you have 2 attempts to find something that suits you! I did try using the higher temp side of the switch, but had fuel vapourisaion problems in hot weather. Quote Link to comment Share on other sites More sharing options...
James Posted December 26, 2012 Share Posted December 26, 2012 One of the advantages of having an ECU is that I can switch the fan on and off at any temperature I like— and even switch it off above certain throttle positions (as the car is moving anyway)I had an issue initially that the engine took a bit too long for my liking to cool back down to a decent temp — I reduced the temp the fan switched on by about 6 or 7 degrees and it worked far better.Thermal runaway is a bit of a knife edge.The fan on my saloon is a bit on the small size and that needs sorting but you get the idea.(This also gives me an idea to ask the MegaSquirt developers to include a fan switch option connected to inlet air temp — can do it myself with wiring and a custom output but it would be very handy to have it done in software) Quote Link to comment Share on other sites More sharing options...
iggy Posted December 26, 2012 Author Share Posted December 26, 2012 been searching around it seems the thread size is 5/8 unf for the temp sender, also according to the haynes manual on the later 2500cc engines the thermostatstarts to open at 83.5 deg c and is fully open between 93.5 to 96 deg c wheather the haynes manual is correct i dont no, so may be a fan switch that cuts in at 100 deg c and brings the temperature down to 84 deg c will work ok Quote Link to comment Share on other sites More sharing options...
iggy Posted December 26, 2012 Author Share Posted December 26, 2012 ive found a company in sussex that specialise in vehicle cooling and sell screw in variable temperature fan switchs with bsp metric and npt threads there called mawsolutions.com Quote Link to comment Share on other sites More sharing options...
piman Posted December 26, 2012 Share Posted December 26, 2012 Hello James,don't forget that the real engine temperature controller is not the fan but the thermostat. As a matter of interest my (2.5L) Mk 1 has a 14" Kenlowe fan and that seems to cope well with all occasions.Alec Quote Link to comment Share on other sites More sharing options...
James Posted December 26, 2012 Share Posted December 26, 2012 Alec,I'm talking about beyond thermostat temps — all I'm saying is that if you let it get a little bit hot it can take a lot more effort to get it back down again than if you catch it earlier.I think my fan measures 10" — it's a slimline Pacet located behind the rad. Works fine as long as you catch it before it gets too hot.James Quote Link to comment Share on other sites More sharing options...
mpbarrett Posted December 26, 2012 Share Posted December 26, 2012 I have used the main car temp sensor. I have added a stabilized 10V supply and then measure the voltage across gauge and then use a small PIC based cct to control the Fan (and switch 3 LEDS, green, orange and Red to show what it is doing). I have programmed it to have some hystersis when the temp pases the threshold (high temp) and then it stays on unitil it drops to a lower limit.. The LED comes on at 50C (green), orange and then red. Bit of a fun really but does show you that the controller is working. I also have an over ride switch.I am not sure it is as stable as it should be. The main temp sensor is a PRT and its fed from a stabulized supply. Will probably improve it over the summer ready for the 10CR.Mike Quote Link to comment Share on other sites More sharing options...
piman Posted December 27, 2012 Share Posted December 27, 2012 Hello James, I wasn't expecting an overheat situation? I thought you were talking about fine tuning the fan running temperature window?Alec Quote Link to comment Share on other sites More sharing options...
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