FramerateUK Posted July 27, 2013 Share Posted July 27, 2013 While I'm sure this might be a case of "they all do that, sir", we spent yesterday driving up the M5/M6 and were stuck in a lot of heavy traffic, in a lot of heat in our Sigma 140. At one point the temp gauge was going as far as it would to the right, past the 120 degree mark! I managed to get it to drop a little by turning the heater on and putting the fans on full.It was fine when moving, but rose quite consistently when stopped in traffic as there was no air getting through the radiator. Everything seemed ok, and the car showed no problems, but the high reading on the gauge was a bit of a worry. Should we be concerned? It's been ok today and we've not been in much traffic. Is there anything we should be doing when we get back from our trip? EDIT: I'm suspecting our radiator fan should be kicking in but isn't. It was rather difficult to check this at the side of the M6....possibly a knackered sensor? Edited by - framerateuk on 27 Jul 2013 16:37:35 Edited by - framerateuk on 27 Jul 2013 18:00:23 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 27, 2013 Member Share Posted July 27, 2013 Yes, you need to sort this out. If the fan isn't cutting in by itself then short the wires to and from the sensor to check that the fan then starts and everything else is working. Jonathan Edited by - Jonathan Kay on 27 Jul 2013 17:07:21 Link to comment Share on other sites More sharing options...
john milner Posted July 27, 2013 Share Posted July 27, 2013 I have a K series and mine hovers around 80 and has never reached 90. My guesses are thermostat not opening enough or fan trouble. Link to comment Share on other sites More sharing options...
Non-M25 Traveller Posted July 27, 2013 Share Posted July 27, 2013 we spent yesterday driving up the M5/M6 and were stuck in a lot of heavy traffic Link to comment Share on other sites More sharing options...
FramerateUK Posted July 27, 2013 Author Share Posted July 27, 2013 Quoting Jonathan Kay: Yes, you need to sort this out. If the fan isn't cutting in by itself then short the wires to and from the sensor to check that the fan then starts and everything else is working. Jonathan Edited by - Jonathan Kay on 27 Jul 2013 17:07:21 Thanks Jonathan, Do you know where the sensor is? There's a connector near the fan itself but there's no sensor to be seen. The supersport has a different fan and rad compared to the 125. Non-M25Traveller... we're driving to Scotland in one day. A/B roads were never an option. Edited by - FramerateUK on 27 Jul 2013 17:22:58 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 27, 2013 Member Share Posted July 27, 2013 Sorry: I don't know the details of the wiring on a Sigma 140. Someone who does will be along in a minute... Jonathan Link to comment Share on other sites More sharing options...
FramerateUK Posted July 27, 2013 Author Share Posted July 27, 2013 Thanks! We've never had overheating problems before, but then it's a lot hotter than normal. It's just bad timing since we're up here for a week! Link to comment Share on other sites More sharing options...
John Vine Posted July 27, 2013 Share Posted July 27, 2013 If your fan's not coming on at all (even when applying JK's trick), try checking that the relay is firmly plugged in. It's the one at the bottom (of seven, I think, but I'm not well versed in the Sigma). JV Link to comment Share on other sites More sharing options...
Z3MCJez Posted July 27, 2013 Share Posted July 27, 2013 I bet it's relay. They're behind the fuses, under the passenger side dash. There are 5 I think with a bigger one in the middle. Check passenger footwell to see if its loose in there first. You would be about the 10th person I know that this has happens to. Including me. Jez Link to comment Share on other sites More sharing options...
The Pikey Posted July 27, 2013 Share Posted July 27, 2013 I also think it might be the relay. Either that or the fuse, the wiring to the fan or the fan of course. I am 99% sure the sigma use the MBA ECU to switch the relay when required so there is no fan switch on the rad. Link to comment Share on other sites More sharing options...
pugwash Posted July 27, 2013 Share Posted July 27, 2013 Supersport 140 sensor is at the back of the engine just in front of the battery. Link to comment Share on other sites More sharing options...
FramerateUK Posted July 27, 2013 Author Share Posted July 27, 2013 Thanks very much for all the replies. I'll have a proper look in the morning when we've got some more light and the midges have disappeared! It seems likely it's something loose as we've not had any problems like this before. When we hired a Sigma 125 last year the temp rose a lot in traffic, but until today ours has been very solid. I'll let you know how we get on :) Link to comment Share on other sites More sharing options...
glasgow Posted July 28, 2013 Share Posted July 28, 2013 A small LED light on dashboard is helpful.... Ian, This thread contains a username copyright violation 😬 Ahmed Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted July 28, 2013 Share Posted July 28, 2013 😬 Link to comment Share on other sites More sharing options...
SKC Posted July 28, 2013 Share Posted July 28, 2013 Check the connection between the fan itself and the chassis / engine harness. Are the terminals all correctly located in the plastic plugs? Have terminals been pushed out the rear of the plugs when the two halves have been pushed together? Have the plugs been left disconnected for some reason (radiator removed and forgot to re-connect the fan!!)? There is no separate sensor for the fan, it's controlled by the ECU water temp sensor and then activated via the relay. Also check the fuse. Regards SKC Link to comment Share on other sites More sharing options...
michaeljclark Posted July 28, 2013 Share Posted July 28, 2013 I had an issue on the way back from the IOM with my Sigma 150, with the help of some fellow 7'ers it was decided that the relay had worked it's way loose or had muck on the contacts on the terminals - once it was removed and confirmed to be working in another 7, all was well again. I'd quite like a fan mod, so I have more control, but as Jason and SKC point out, the sensor is the ECU, so not sure of the best route to "do" the mod (other than fused wire from battery to a switch and then off to the fan - which seems altogether too simple ❗) Mike Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 28, 2013 Member Share Posted July 28, 2013 Quoting SKC: There is no separate sensor for the fan, it's controlled by the ECU water temp sensorHow can you test the fan comes on correctly with this set-up? Could you short the lead to the sensor or do you need to insert an appropriate resistor? Or is there a test mode? Thanks Jonathan Link to comment Share on other sites More sharing options...
The Pikey Posted July 28, 2013 Share Posted July 28, 2013 The ECU sends a negative feed to the relay when it wants the fan on. This flicks the relay on which sends a positive feed to the fan. The negative for the fan comes from the bunch of negatives bolted to the chassis under the nosecone. The ON/OFF temps are set in the ECU so you will need the interface from SBD to access this. When the fan is supposed to be on it pops up on the laptop. Thats how it works on mine anyway.. Jason Link to comment Share on other sites More sharing options...
FramerateUK Posted July 29, 2013 Author Share Posted July 29, 2013 Well thanks for the advice everyone! I gave the relays a good push to make sure they were all in, and I cleaned up the fan cables. We gave it a quick test today and the fan was most definitely coming on around 90 degrees until it cooled the car back down. Admittedly it wasn't quite so hot but at least it seems to be working :) Thanks again! Link to comment Share on other sites More sharing options...
Z3MCJez Posted July 30, 2013 Share Posted July 30, 2013 The relays do seem to be a weak point with loss through vibration common. Worth giving them a push once in a while. I've also tried to tape them in, but with limited improvement. Glad it's up and running again Jez Link to comment Share on other sites More sharing options...
John Vine Posted July 30, 2013 Share Posted July 30, 2013 Pleased to hear you've fixed it. JV Link to comment Share on other sites More sharing options...
TobyCoulson Posted July 30, 2013 Share Posted July 30, 2013 If you haven't done it already might be worth upgrading to a larger rad and fan. I installed the radtec one on my Sigma 150 when the old plastic factory one gave up the ghost. Had no issues with it since. Link to comment Share on other sites More sharing options...
Garth Posted July 30, 2013 Share Posted July 30, 2013 The manual for my Sigma 125 says the optimum temperature for the coolant is 110 degC! Are we running our cars too cold? Link to comment Share on other sites More sharing options...
FramerateUK Posted July 30, 2013 Author Share Posted July 30, 2013 Quoting TobyCoulson: If you haven't done it already might be worth upgrading to a larger rad and fan. I installed the radtec one on my Sigma 150 when the old plastic factory one gave up the ghost. Had no issues with it since. Thankfully the 140 already has a larger fan and rad than the standard 125. I'll be keeping my eye on this though, and giving those relays a push every now and then! Link to comment Share on other sites More sharing options...
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