Adrian M Posted May 3, 2006 Share Posted May 3, 2006 I have an ex race R400 engine which I have fitted to my Superlight and I’ve been having a few over heating problems. The cooling system consist of a triple core radiator, silicone hoses (with a bleed T), rad fan switch located in the rad and a standard thermostat. During the Anglesey trackday the engine overheated as I pulled into the paddock after a session and it spat its coolant although while it was out on track the water temperature was fine. Last Sunday after some enthusiastic road driving I pulled into a petrol station and the temperature rocketed! The water rail was touching 100 but the thermostat hadn’t opened and the rad fan hadn’t cut in but all the time I was driving the temperate was fine. It seems that the thermostat isn’t opening while I’m driving and when I come to a standstill and the airflow drops the engine starts to overheat. If I start the engine from cold and allow it to run up to temperature the thermostat opens fine and the fan comes on right on queue. The system has been bled many times. Also I have pressure tested the cooling system to 15psi and they’re no leaks and the system will make 5psi while idling. I’ve done a hydrocarbon test which was clear and they’re no other signs of HGF. The way I understand it a thermostat either works or it doesn’t and if it doesn’t it should stick in the open position? My thoughts are to ditch the thermostat and switch to the ECU rad fan switch which is the R400 race configuration. Also maybe fit a remote thermostat in the radiator bottom hose if it runs too cool? Anyone got any thoughts? Ade Link to comment Share on other sites More sharing options...
Myles Posted May 3, 2006 Share Posted May 3, 2006 My thoughts? Sounds similar to what I experienced on Mav's trackday - but I've not had a chance to do as much diagnostic work as you. My 180+bhp 1.8 exhibited perfectly-behaved temps on track - but the coolant kept rising in the bottle and spitting a small amount out (until I fitted a new cap - this kept the rise in check, but it was still running higher than normal). At only one point during the track sessions did I see any problems - that was taxiing out to the pitlane - temp did a few rocket rises but mostly sorted itself out. I took it out on track and thrashed it - the temp was fine while running. At the end of the day, I left it idling (had some starting issues) while everyone else packed up - during which time the temp had reached 100. Killed it and found the rad was cold. Took the stat out completely the next morning and have been running it that way since (while waiting for new silicone hoses, clamps and an R500 stat unit) - the coolant level dropped slightly on the run home from Anglesey (not major attempts made to bleed it, but with no stat, you'd have thought it would sort itself out pretty easily. Topped it up and haven't noticed any drop in coolant since (I drew a dotted-line on the tank to make measurement a bit more reliable). Dunno guv. I'm hoping it was a stuck stat - but quite why that should force the coolant level up, I'm not sure. Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted May 4, 2006 Support Team Share Posted May 4, 2006 It could be a dodgy thermostat - if it sticks, it could easily stick closed. I would suggest replacing with a new 82 degree 'stat and drill a small (3mm) hole in it - this allows some hot water to the other side of the 'stat so speeding up the opening of it and reducing thermal shock to the engine block. I wouldn't ditch the 'stat completely as it will take forever to warm up and in fact in winter is unlikely to reach operating temperature. Yellow SL #32 Link to comment Share on other sites More sharing options...
Adrian M Posted May 4, 2006 Author Share Posted May 4, 2006 Myles, my problems seem very similar to yours. How have you found running without a stat and is removing it as bad as everyone says? I’m going to remove mine this weekend and test it, I think I’ll fit a remote 82º one in the radiator bottom hose. Ade Link to comment Share on other sites More sharing options...
Myles Posted May 4, 2006 Share Posted May 4, 2006 Adrian - well, the coolant in mine sits at around 50 degrees C and the oil about the same - bit warmer. The argument goes along the lines that there is likely to be a fairly extreme temperature gradient across the cylinder head - not good. Also, the oil isn't up to temp and so is creating more drag on the engine and also won't be flowing as well. My OP has certainly been running a good 10psi higher than it does normally. All-in-all, it's not ideal. FWIW, I've been running the 74 degC 'R500' stat until now - and have a new one from CC to put back in - this has kept the temps nice and stable (until it failed...) Interestingly, this stat (badged as a Rover part) has a moderate hole pre-drilled in it - with a crude (but effective) one-way valve installed in the hole (I'll take a pic later). I'm tempted to remove the 'valve' so that I always have *some* flow. Anyway, as an aside, this goes to show just how darned-good the Radtec radiator is - it can dump a lot of heat very effectively... Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Johnty Lyons Posted May 4, 2006 Share Posted May 4, 2006 I'm running a R500 stat and a Radtech plus a laminova on a 240 BHP Dry Sumped[ 7 Ltrs oil] K I have had to mask off the bottom 1/3 rd of rad to get any temp into the system at all otherwise it all sits at 55Deg water and oil. I make a point of starting the car and getting it up to full temp before I move otherwise it NEVER warms. I am about to ditch the existing stat and go back to a 82 the lower one was fittted pre USA as a precaution, and I did see oil and water temps of 100 Deg whilst there BUT it must be remembered that then I was seeing ambient temps well over 90Deg. It was me that suffered not the Car I had nostrel burn [not recommended] jj Link to comment Share on other sites More sharing options...
Mark w Posted May 4, 2006 Share Posted May 4, 2006 Adrian I have an R400 and experienced very similar symptoms to you.Car would run fine on the open road but as soon as i pulled in to a town or stationary traffic the temperature would rise very quickly . After a few days operating like this the coolant decided to blow out via the expansion bottle. As the engine had done less than 1000 miles it went back to the factory. Caterham tried the obvious ( thermostat , bottle cap etc ) and then decided to strip the head. The fault was diagnosed as a pourous head which was replaced under warranty. The car has now done another 5000 miles including a few track days and hasnt missed a beat. I run a 82 degree thermostat ( with a small bypass v moulded into the seat to allow a bit of flow at all times ) and triple pass rad. Temperature normally rums at 75 ish ( a bit less at full blat on a cold day ) up to 83 / 84 in traffic. I have a large fan that comes on at 84 which immediately stops any further rise and then pulls the temp down. I hope your fault is easily remedied but it does seem very similar to my experience ☹️ Link to comment Share on other sites More sharing options...
Adrian M Posted May 5, 2006 Author Share Posted May 5, 2006 I’ve ordered a 74° stat and will fit that over the weekend (if it turns up on time). I’m not sure weather drilling a small hole in it will help. Also I’m not sure which rad fan switch to use? Ade Link to comment Share on other sites More sharing options...
Mark w Posted May 5, 2006 Share Posted May 5, 2006 I suspect with a 74 degree stat you will run too cold in anything other than v hot weather. Let us know what happens. Link to comment Share on other sites More sharing options...
Mark w Posted May 5, 2006 Share Posted May 5, 2006 If you are using the 74 ( or 82) stat then i would suggest an R500 fan switch. Edited by - Mark W on 5 May 2006 16:55:53 Link to comment Share on other sites More sharing options...
Adrian M Posted May 5, 2006 Author Share Posted May 5, 2006 I guess the R500 fan switch is the ECU relay one, I’ve already got one of these fitted but as the trigger temp was lower than the old thermostat I’m still using the fan switch in the rad, swapping between the two is only one plug. Ade Link to comment Share on other sites More sharing options...
Myles Posted May 5, 2006 Share Posted May 5, 2006 Mark W - depends what 'too cold' is. Mine ran at mid 70's coolant and slightly-higher oil on the road. Being as I run an Apollo, the actual oil temp is closer to mid-80s (there is a faux cooling-effect when underway due to the temp sensor location) Adrian - I think Adrian *is* referring to the fan switch in the rad... My preferred solution is to fit a fan override switch as well as the R500 switch - when entering traffic, I used to flip it on - and this kept the coolant variation down to just a few (5-8ish) degrees. Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Mark w Posted May 5, 2006 Share Posted May 5, 2006 The reason i said "too cold " is because i have tried two 82 degree stats and with the permanent bleed hole and a tendancy to part open before 82 degrees the coolant temperature as measured by the Stack is normally in the mid 70s. With the 74 degree stat and the same set of circumstances i suspect you will see temps as low as mid to high 60s which in my opinion is " too low " See also Johntys comments above. The fan switch i was referring to is the standard screw in one which goes in the rad.I have a bypass switch and relay as well but not the ECU overide. Link to comment Share on other sites More sharing options...
Adrian M Posted May 9, 2006 Author Share Posted May 9, 2006 I fitted the 74° thermostat on Sunday and it was as tricky as I expected. I tried it with the bobble valve but ended up removing it as it looked as if it would only get stuck. As yet I haven’t had a chance to test the car yet but the 88° thermostat that Caterham supplied was far to high. There are a few photos of the new thermostat here. I still have the standard rad fan switch in the radiator, a override switch and the ECU switch, although the ECU seems to trigger the fan too low. Ade Link to comment Share on other sites More sharing options...
davef Posted May 9, 2006 Share Posted May 9, 2006 Adrian - I hope it is all working fine now - I'm looking forward to seeing it on Saturday at Dunsfold. Which seesion are you on? I installed one of the 82 degree stats from Eliseparts in mine - and drilled two 3mm holes through it. So far (~30 miles) this has been fine (touches wood.....) Dave Link to comment Share on other sites More sharing options...
Adrian M Posted May 9, 2006 Author Share Posted May 9, 2006 Dave, I’m in the AM session on Saturday what’s your car like and I’ll keep an eye out for you? I had a chance to run it up to temp this evening and bleed the system and it seems to have made a big difference. I hope the 74º stat isn’t too low, I don’t much fancy changing it again, my arm still hurts! Ade Link to comment Share on other sites More sharing options...
davef Posted May 10, 2006 Share Posted May 10, 2006 Mine's an Ali and Black Superlight, Dave Link to comment Share on other sites More sharing options...
Mark w Posted May 11, 2006 Share Posted May 11, 2006 Adrian when you have run it for a while with the 74 degree stat can you tell me what temperatures you are seeing. thanks. Link to comment Share on other sites More sharing options...
Adrian M Posted May 11, 2006 Author Share Posted May 11, 2006 Mark so far I’ve only run it up to temperature a couple for times to bleed the system. The stat opens up much earlier and the fan*****s in at about 80° as opposed to 90°. I’ll report back after I’ve tried it at Dunsfold and on the road. Dave I’ll keep an eye out for you, mine looks something like Ade Link to comment Share on other sites More sharing options...
Myles Posted May 11, 2006 Share Posted May 11, 2006 The fan does what? Not been looking at Arnies Beetle again have you? Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Adrian M Posted May 12, 2006 Author Share Posted May 12, 2006 ooops!! Ade Link to comment Share on other sites More sharing options...
Myles Posted May 13, 2006 Share Posted May 13, 2006 Update from the front... After my original (1-year-ish old) R500 74 deg C stat failed at a trackday a month or so back, I've been running without a stat at all. Today, I fitted a new R500 stat (the 'new' design with the crude bypass/bleed valve) at the same time as replacing my main hoses with silicone jobs. As reported previously, my old running temps were around the 74ish deg C level for coolant and a few degrees higher for oil. Although it's a cool (and very wet...) day and I was only running at normal traffic speeds, the temps with the new stat are a good 5 or more degrees cooler - and this *is* getting into the 'too-cool' region as far as I'm concerned... I don't know if the difference is down to: i) The original stat being a duffer (it failed eventually) ii) Differences in design (the new one has the valve widget) iii) Natural manufacturing tolerances (they are hardly precision instruments...) I'll keep an eye on it, but I'm starting to believe that maybe JJ wasn't suffering from a tea-overdose when he posted his findings... Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
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