CtrMint Posted March 15, 2020 Share Posted March 15, 2020 Hi,I'm currently still running in my 620R, although the foul weather this year has limited times when I can run the car. Those dry days free from salt have been bitterly cold. I've only managed about 350 miles so far, of which 100 miles was probably the journey home on collection. I've noticed I'm struggling to maintain coolant temp at anything over 40mph, I'm assuming the cold is too much for the cooling. This is limiting my driving as I obviously want to have all fluids good and hot.I'm wondering if it is sensible to block up the radiator on the outside of the nose cone? I'm sure I've seen pics of Sevens on circuit with gaffer tape blocking the nose cone.If it is a good idea, has anyone got any recommendations regarding techniques. I don't want to damage the finish on the mesh with tape that pulls either the paint or powder coat off. Not sure if it's important, but I suspect the diligent members will ask, the fan kicks in and holds the temp when stationary etc, so I think the coolant circuit is working, the car is just over cooling in this cold temps.Thanks in advance for the input. Link to comment Share on other sites More sharing options...
Jonathan Kay Posted March 15, 2020 Share Posted March 15, 2020 Something like corrugated plastic sheet with cable ties? You can put it on the inside or the outside of the grille.SM25T's solution.(One Member has a beautiful remotely controlled shutter system... )Jonathan Link to comment Share on other sites More sharing options...
CtrMint Posted March 15, 2020 Author Share Posted March 15, 2020 Thanks Jonathan.I've been mulling it over and wondering whether the stat might be at fault. Could it be stuck open I wonder. The reason why I say that is the car is doing pretty poor economy too. Having read around the topic it seems a cold engine will produce poor economy. I don't want to start pulling the stat out, since the car is under warranty equally, I can't really get it back over to Oakmere with ease.Is there anyway you can validate a thermostat without pulling it out? Link to comment Share on other sites More sharing options...
Jonathan Kay Posted March 15, 2020 Share Posted March 15, 2020 I don't know the layout of your cooling system but there are people who do...Yes, by feeling the appropriate hoses you can tell when the thermostat opens. I've never had the chance to play with a thermometer gun but that should also work.Jonathan Link to comment Share on other sites More sharing options...
CtrMint Posted March 15, 2020 Author Share Posted March 15, 2020 just been and had a nose. Wow it's complicated under there. If the thermostat is in the same location as the 360/420 then it's within some custom machine block thingy stuck on the side. I've no chance of getting to it. The whole system is totally different too, seems to run anti clockwise round the car, unlike the clockwise motion of the 420. Link to comment Share on other sites More sharing options...
CtrMint Posted March 15, 2020 Author Share Posted March 15, 2020 Delving into this I found the following thread.https://www.lotus7.club/forum/techtalk/620s-temperature-gauge?page=1poor fuel and economy and low temps, am I missing a stat on a 620R? Link to comment Share on other sites More sharing options...
CtrMint Posted March 15, 2020 Author Share Posted March 15, 2020 Delving into this I found the following thread.https://www.lotus7.club/forum/techtalk/620s-temperature-gauge?page=1poor fuel and economy and low temps, am I missing a stat on a 620R? Link to comment Share on other sites More sharing options...
Tazio Posted March 15, 2020 Share Posted March 15, 2020 Is a typical 7 problem, both my VX and BDR suffer the same, I just blank off the lower 2 and half inches, works for me. Link to comment Share on other sites More sharing options...
CtrMint Posted March 15, 2020 Author Share Posted March 15, 2020 I know they have a habit of running cool, but I would like to try and figure this out. I'm not sure what the benefit of not having a thermostat really is, vs having one. Link to comment Share on other sites More sharing options...
Mark w Posted March 15, 2020 Share Posted March 15, 2020 The early 620Rs had no stat .In 2016 a modification to the stat housing was made and a stat was fitted .Even with the stat fitted mine runs cold when ambient temps are low .I use a piece of rigid plastic board fitted with low tack electricans tape to blank off the lower 100mm of the radiator grille .Seems to work fine , you just need to remember to remove it at the right time . Link to comment Share on other sites More sharing options...
7 wonders of the world Posted March 15, 2020 Share Posted March 15, 2020 Cant believe they are running less than an 82 degree stat which if the system has been designed correctly wll maintain the correct temp with a quick warm up circa 4-5 miles.#As for running in Mark get it warm and give it full beans full revs over the mountain or where ever you can, pottering around will do nothing for bedding the engine in correctly, especially if its overcooled and with what seems to be and over fueled map - bore wash and rebuild here we come. Link to comment Share on other sites More sharing options...
StevehS3 Posted March 15, 2020 Share Posted March 15, 2020 Just to satisfy my curiosity, why would a car run cool when fitted with a thermostat to control the temperature by varying the flow between the bypass and radiator? I hear this all the time and never understand it. Link to comment Share on other sites More sharing options...
CtrMint Posted March 15, 2020 Author Share Posted March 15, 2020 Covered it up this afternoon with some thin flexible plastic wrapped in electrical tape, it was running between 95c and 75c depending what I was doing. ~75c at 80mph over the Mountain, it was baltic up there. Through the slower villages it sat mostly at 85c. From Ramsey to Ballacraine it seemed pretty normal in terms of temps.Neil as for giving it the beans, its been driven up to 5k, but I don't have the confidence in lower gears its so rapid, then in higher gears its a bit too quick for the public road this time of year. Plus I'm nervous of the ZZRs in the cold. Link to comment Share on other sites More sharing options...
7 wonders of the world Posted March 15, 2020 Share Posted March 15, 2020 It shouldn't in a correctly designed and functioning system, especially in a modern set up. Link to comment Share on other sites More sharing options...
Mark w Posted March 15, 2020 Share Posted March 15, 2020 "Just to satisfy my curiosity, why would a car run cool when fitted with a thermostat to control the temperature by varying the flow between the bypass and radiator? I hear this all the time and never understand it." I think it's because the thermostat has a bypass ( look at the groove in the housing picture ) which feeds cold water through even when it's not needed plus the radiator is oversized to cover peak load so the temperature drop is too extreme in low ambient temperatures in relation to the demand . Link to comment Share on other sites More sharing options...
7 wonders of the world Posted March 15, 2020 Share Posted March 15, 2020 The bypass feeds HOT water and allows the stat to respond in a more timely manner being fed in th case of the Duratec via a 19mm hose direct form the water outlet behind No 4.Once the hot water being fed over the stat reach the critical temperature the stat opens allowing cool water from the rad bottom hose to flow into the engine and hence as the radiator circuit is now open hot water to flow to the radiator from the same outlet albeit via a full size hose.It then shuttles back and forth being moderated by hot bypass and cooler radiator return.NB as the stat opens it closes off the bypass circuit, which is only reopens as the stat is cooled and closes again.Whilst there are packaging limitations on the 620 but this is no excuse for a poorly functioning cooling circuit, bearing in mind the DS runs circa 7Ltrs of oil via a full flow oil cooler but again this runs with no oil stat - the poor engine will never reach a reliable operating temperature unless many horses are being unleashed, running the risk of dropping back into the realms of warm up fueling and therefore and washing the bores. Link to comment Share on other sites More sharing options...
Mark w Posted March 16, 2020 Share Posted March 16, 2020 Re#16 Theres NO hot bypass / return feed into the stat on a 620 Link to comment Share on other sites More sharing options...
7 wonders of the world Posted March 16, 2020 Share Posted March 16, 2020 Are you sure theres no bypass as this goes into the metal pipe pressed into the block itself adjacent to to the stat housing, the hose that normally fits onto the stat (absent on the photo above) is the heater / expansion bottle return. Link to comment Share on other sites More sharing options...
Mark w Posted March 16, 2020 Share Posted March 16, 2020 OK We may be debating terminology here .Theres a FILL pipe connected to that spigot that comes from the expansion bottle .The expansion bottle just has mini air bleed pipe serving it ( connects off the top of the return water rail ) . Whilst there will be some flow via this route it will probably be minimal .When you said bypass pipe i understood that to mean a full flow return pipe from the back of the block direct to the stat housing .Heres a picture of a 620 in build .And one stripped to have the modified supply pipe fitted to enable a stat to be fitted .( old supply pipe still in place ) Link to comment Share on other sites More sharing options...
Mark w Posted March 16, 2020 Share Posted March 16, 2020 " bearing in mind the DS runs circa 7Ltrs of oil via a full flow oil cooler but again this runs with no oil stat - the poor engine will never reach a reliable operating temperature unless many horses are being unleashed, running the risk of dropping back into the realms of warm up fueling and therefore and washing the bores."Good points made here , some tin foil round the oil cooler can reduce overcooling the oil .Ive got an unlocked ECU on my car and have adjusted the cold start ,over fueling , cut off point to a lower setting so that it doesnt do this . It doesnt seem to have any adverse effects on running . Link to comment Share on other sites More sharing options...
Jonathan Kay Posted March 16, 2020 Share Posted March 16, 2020 Does anyone have a cooling system diagram for the 620, please?ThanksJonathan Link to comment Share on other sites More sharing options...
Mark w Posted March 16, 2020 Share Posted March 16, 2020 Why ? I've got a car and can see it ! Link to comment Share on other sites More sharing options...
Jonathan Kay Posted March 16, 2020 Share Posted March 16, 2020 It might help CtrMint and other Members on their own cars, and would definitely help me to understand the discussion.Jonathan Link to comment Share on other sites More sharing options...
Mark w Posted March 16, 2020 Share Posted March 16, 2020 Link to comment Share on other sites More sharing options...
Jonathan Kay Posted March 16, 2020 Share Posted March 16, 2020 ThanksJonathan Link to comment Share on other sites More sharing options...
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