JP Posted March 31 Share Posted March 31 Shaking down my 1.6K series rebuild this morning and it seemed that the cooling fan was slow to kick in. Here is a pic of the temp at which it activates - does this look right, please? Link to comment Share on other sites More sharing options...
SM25T Posted March 31 Share Posted March 31 Look at the marks on the fan switch in the top of the radiator. Possibly something like open at 92 and close again at 87 ? Sender is not very reliable. What thermostat do you have fitted . I use an 82C to keep things cool at any ambient. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted March 31 Member Share Posted March 31 Looks too high to me. Check that the fan comes on reliably by shorting out the switch by hand. Where is the switch? And is the system full of coolant? Jonathan Link to comment Share on other sites More sharing options...
SM25T Posted March 31 Share Posted March 31 Examples for fan switch Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted March 31 Member Share Posted March 31 Does the indicated temperature come down as soon as the fan cuts in? Jonathan Link to comment Share on other sites More sharing options...
Colin_T Posted March 31 Share Posted March 31 7 minutes ago, Jonathan Kay said: Does the indicated temperature come down as soon as the fan cuts in? Jonathan confirm the gauge is reading correct against another known calibrated means. As Jonathan has said, “Indicated temperature” is a key term here. Amount of times I used to get customers complain their engine was running hot and they’d carry out all manner of tests and modifications only for me to check it with a laser thermometer and it be 20-30 degrees cooler than the gauge was showing. Link to comment Share on other sites More sharing options...
JP Posted March 31 Author Share Posted March 31 I'll check the markings on the switch. It has the original (bottom hose) thermostat that the car came with. When finally up to temperature and running normally, both water and oil temp sit on the "80" mark. I seem to recall checking with a laser thermometer during my rebuild and the rad temp and top hose temp were around 90-92 when the fan started. The temp does come down promptly when the fan starts. System is full, with no leaks. Given SM25T's comment, I wonder if it is just the gauge... Is the standard thermostat 82 degrees? Link to comment Share on other sites More sharing options...
SM25T Posted March 31 Share Posted March 31 No, I recall it was higher in the 80s Link to comment Share on other sites More sharing options...
Miker7 Posted March 31 Share Posted March 31 Standard is 88 degrees start to open. I've recently fitted the 82 degree and had a worry it was too cold as the gauge didn't get up to temperature (new to me car). Then discovered the ECU temperature is always 10 degrees higher than the gauge. Now don't know which to trust so will be getting a combination of the mulitmeter thermocouple and infra red sensors out in the near future to figure it out (or have more temperatures to worry about not matching each other 😀) Link to comment Share on other sites More sharing options...
JP Posted April 1 Author Share Posted April 1 (edited) Thanks all - I'm going to get the laser thermometer out now and investigate thermostat opening and fan activation. I may have further queries... Edited April 1 by JP Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted April 1 Member Share Posted April 1 You can also test thermostats by dunking them in jugs of hot and cold water. And in situ by feeling hoses. Jonathan PS: I'd be very interested in experiences with remote thermometers and probes on multimeters etc. They could make it much quicker to solve a lot of problems... Link to comment Share on other sites More sharing options...
SM25T Posted April 1 Share Posted April 1 Contactless laser thermometers are very useful, but give false readings if aimed at reflective surfaces, like unpainted aluminium or steel components. If you have to use such a surface it is suggested attach a piece of tape first. Link to comment Share on other sites More sharing options...
JP Posted April 1 Author Share Posted April 1 (edited) Right - been out with the IR thermometer. I must say that I found it tricky to get consistent readings - maybe my cheap IR thermometer is at fault or maybe it is just difficult to focus the IR sensor on particular surfaces in a hot engine bay? Anyway I wonder if I have an 82deg thermostat. I judged thermostat opening by feeling the bottom J hose. It became hot with the following readings: Dash gauge - 78 Thermostat black plastic body temp - 85 deg J hose - 77deg Fan on temps: Dash gauge ~95-100 Fan switch - 94-95deg Fan off: Dash gauge - ~90 deg Fan switch temp - 86-87 degrees I have heard that there is a valve in the top hose bypass at the front of the right side of the head that is prone to blocking - my bypass hose feels warm soon after starting and so I suspect that is patent. So, I think I will leave the thermostat. It seems sensible to change the fan switch. It must be over 15 years old and lived in a car that has barely been run for that time. Tempted to opt for a 77-82 option as I've always been twitchy watching the temp gauge rise when out for a summer blat and the arriving at a traffic jam. I note that the switch in the CC parts site is described as 86-95deg... I'm reluctant to drill another hole in my dashboard, but I am considering adding a fan override switch. For those that have done it, where do you tend to mount the relay? Edited April 1 by JP Link to comment Share on other sites More sharing options...
JP Posted April 2 Author Share Posted April 2 On reflection, I guess the first question to answer is, "What temperature should the K-series run at?" I'm finding that a hard question to which to find a definitive answer. Can any K-series gurus help? Link to comment Share on other sites More sharing options...
SM25T Posted April 2 Share Posted April 2 That is too low. The fan would always be on, draining the battery ! The thermostat should do most of the work, with the fan coming on at higher temperatures, ie when stopped in traffic. Mine indicates a steady 80C all day long. Link to comment Share on other sites More sharing options...
SM25T Posted April 2 Share Posted April 2 Change the single wire sender first. Cheapest option. They can be unreliable Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted April 2 Member Share Posted April 2 1800 K used on road and (now very occasional) track sessions. Standard cooling system 82°C thermostat (on the advice of RatRace) Sender to the gauge replaced Fan switch replaced, now 95°C Comma G30 coolant Runs at indicated 80°C, and fan brings it smartly back to that when needed But cooler than that when cruising on cold days. I think about blanking off part of the radiator but I haven't got a round tuit. Jonathan Link to comment Share on other sites More sharing options...
Mick Day Posted April 2 Share Posted April 2 Fan is switched by the aftermarket ECU. 86 on, 82 off. 82 thermostat. Engine sits at 77. Link to comment Share on other sites More sharing options...
Miker7 Posted April 2 Share Posted April 2 4 hours ago, Mick Day said: Fan is switched by the aftermarket ECU. 86 on, 82 off. 82 thermostat. Engine sits at 77. What ECU do you have? If i recall correctly the Rover ECU is still in 'warm up' mode if its seeing 77 degrees. (this is a wonder i'm having currently with my untested setup). Link to comment Share on other sites More sharing options...
Mick Day Posted April 2 Share Posted April 2 GEMS.... DVA engine Link to comment Share on other sites More sharing options...
JP Posted April 2 Author Share Posted April 2 Thanks everyone. It seems that I should probably just leave well alone for now and maybe find an 82deg thermostat and new fan switch for next I drain the coolant... Link to comment Share on other sites More sharing options...
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