Boombang

I'm looking at racing and thought a wanted ad would be worthwhile. Looking for a Sigmax car for Caterham Graduates race series. I would consider a Sigma 135 or 150. Likewise I am looking for a suitable good quality named trailer to suit - must be under 5m total length and at least 1.75m wide bed. I currently have a road R300 D, 4k miles, white pearl with orange stripes that I would be selling to make space. Beautiful car with Kevlar seats, heater, screen and doors. Comes with an R300 number plate. Valued at ~£29k. Would consider a trade of race car, trailer and cash against the R300 if somehow the stars aligned.

Hi Benton have you got a close up on how you mounted the mirrors please?

Thanks Jonathan - I posted my reply above this one in the garage then edited when sat back inside, so it has changed since you replied. Do agree though gauge, sensor and wiring look fine. Stat is opening early and the correct temp for rad fan coming on is TBC but suggested to be around 96 and this thread and post is useful... /comment/2136002#comment-2136002 Without Easimap and seeing what the ECU is showing it's hard to be certain, but everything points to the stat itself seeming to be worthy of a change.

Tracking my notes, following suggestions above. Single pin sender in submarine. Connecting the sensor wire straight to earth maxes the gauge out. Earth on the submarine has decent continuity to battery earth. I warmed the car up at 2k revs, reading continuity through the sensor you can see the reading changing as warms up. As warming up I checked the sensor body using a temp probe and the gauge was reading within a couple of degrees all the way from 60-70 degrees . When the sensor body hit about 70 on my temp probe with an indicated 70 on gauge the rad started to get hot, suggesting stat starting to open around then - obviously water inside will be hotter than body but still suggested stat is opening low if it should be 80? Got it up to an indicated 78ish on gauge and red fan kicked in for maybe 15 seconds. At that point it would sit a shade under 80 on gauge and sit there with fan coming on every few minutes. At that point stat housing is ~85 on temp probe, slowly climbing to about 88 after 15 mins. Hoses are all between 74 and 82 at the seeming equilibrium with car idling, outside it is perhaps 15 degrees today. So that all suggests stat is opening early and worthy of a change. That said if the rad fan is coming on sub 80 will it not be on almost all the time with an 82 stat? What temp should the rad fan kick in and which sender does it use to trigger switching the fan on?

The car is a recent purchase and for various reasons I have only been able to drive it a couple of times. When stationary I believe it still sits at an indicated 70 degrees with the fan going on and off periodically - the day I picked up it was high 20s and crawling round the M25 the needle hardly moved once hot. Yesterday I noticed the temp dropping when doing an easy 50-60mph down a lane, hence any mention of the a stuck/missing stat. If the reading is miles out, as I suspect, it might not be overcooling that much and could simply be a low temp stat.

Thanks for that link - I'll do some checking on the other advice.

My R300D is showing a coolant reading on the gauge of just under 70 degrees. Fan comes on and off as expected, rad and all hoses are getting hot, heater blows hot and I can't find any sort of airlock nor expect one given the system seems to be working. Coolant at max and expansion tank is lightly pressurised when running and hot). A side thought is a stuck (or missing) thermostat but I've not yet had time nor have sussed out enough to check that by montoring which hoses warm up. That wouldn't explain not getting over 70 though. Any other thoughts about a faulty sender (location in the submarine?) and/or the gauge, and is there a way to calibrate?