Jonathan Pounsett Posted July 16, 2023 Share Posted July 16, 2023 The Manta gauge always seems to run hot, never in the red but always nudging it, so I’m fitting an additional gauge that shows the exact temperature. I thought I could simply splice the gauge wire sending one wire to each gauge. It doesn’t work! The Manta gauge appears to work as normal and when I disconnect it the new gauge springs to life. What do I need to do to make both gauges work at the same time off the same wire? Quote Link to comment Share on other sites More sharing options...
Sutty2006 Posted July 16, 2023 Share Posted July 16, 2023 Have you replaced the voltage regulator behind the dash yet? They are the most unreliable part on a manta, I know folk to have boxes full of them, all burnt out. You can get replacement on eBay. I had this issue with my 1.8, would always run red hot, I fitted extra fans and new viscous, but still ran hot. Replaced the regulator over 10 years ago and never looked back. https://www.ebay.co.uk/itm/285235278029?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=SpBAFWooRDC&sssrc=4429486&ssuid=oSyz5_rPQeO&var=&widget_ver=artemis&media=COPY 1 1 Quote Link to comment Share on other sites More sharing options...
Jonathan Pounsett Posted July 16, 2023 Author Share Posted July 16, 2023 1 hour ago, Sutty2006 said: Have you replaced the voltage regulator behind the dash yet? They are the most unreliable part on a manta, I know folk to have boxes full of them, all burnt out. You can get replacement on eBay. I had this issue with my 1.8, would always run red hot, I fitted extra fans and new viscous, but still ran hot. Replaced the regulator over 10 years ago and never looked back. https://www.ebay.co.uk/itm/285235278029?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=SpBAFWooRDC&sssrc=4429486&ssuid=oSyz5_rPQeO&var=&widget_ver=artemis&media=COPY Is this the same thing? 1 Quote Link to comment Share on other sites More sharing options...
Sutty2006 Posted July 16, 2023 Share Posted July 16, 2023 Yes. Bin it and buy that better one. 1 Quote Link to comment Share on other sites More sharing options...
BerlinettaBoy Posted July 17, 2023 Share Posted July 17, 2023 13 hours ago, Jonathan Pounsett said: The Manta gauge always seems to run hot, never in the red but always nudging it, so I’m fitting an additional gauge that shows the exact temperature. I thought I could simply splice the gauge wire sending one wire to each gauge. It doesn’t work! The Manta gauge appears to work as normal and when I disconnect it the new gauge springs to life. What do I need to do to make both gauges work at the same time off the same wire? Is it getting enough power on the circuit to run both gauges at the same time? I have no idea about car electrics, but I am part P, and sounds like it could be a lack of ampage issue. I may well be completely wrong though 😅 1 Quote Link to comment Share on other sites More sharing options...
Sutty2006 Posted July 17, 2023 Share Posted July 17, 2023 The first port of call with any temp/fuel gauge issue is to bin that original regulator and put a reliable one in. They were on their way out 20 years ago so I’m surprised it’s lasted this long! 🤣 1 2 Quote Link to comment Share on other sites More sharing options...
®evo03 Posted July 17, 2023 Share Posted July 17, 2023 Just to add this voltage reg is push in, three spades if I remember correctly. They are old school turn of the century tech, springs widgets and gadgets inside, no hamster though! 2 Quote Link to comment Share on other sites More sharing options...
Sutty2006 Posted July 17, 2023 Share Posted July 17, 2023 35 minutes ago, ®evo03 said: Just to add this voltage reg is push in, three spades if I remember correctly. They are old school turn of the century tech, springs widgets and gadgets inside, no hamster though! Correct! The old ones are a winding round a metal doohicky that burns out. The new ones a made of magic crystals and electrodes that only come from space. Brilliant technology and is wholly reliable. 2 1 Quote Link to comment Share on other sites More sharing options...
Jonathan Pounsett Posted July 17, 2023 Author Share Posted July 17, 2023 I changed the regulator and now my new gauge “bounces” so I have ordered the new part as recommended by @Sutty2006. I don’t think I can do what I’m trying because I believe the gauge is reading the voltage or resistance and adding another gauge to the same wire messes that up. I think I need to run a new separate wire 🤷♂️ or insert a switch to toggle between gauges. 2 Quote Link to comment Share on other sites More sharing options...
cam.in.head Posted July 17, 2023 Share Posted July 17, 2023 you are correct. the existing guage has a simulated 10v applied to it and this then goes to earth via the temp sensor which is a thermistor. it gives a given variable resistance at a given variable temperature so if you tryto run another guage from the thesame wire it will mess up the resistance and neither guage will work accuraetly. BUT as mentioned earlier ,its 99% of the time the voltage regulator that fails.and causes the guage to overread ( along with the fuel guage too ). replace it and all should be well. ( its a fiddly job !) a basic way to check if yours has failed. turn the radio on and tune into dead air between stations on AM.then turn on the ignition. all should be quiet for a 10 - 15 seconds and then you should hear the regulator opening and closing its contacts with a series of clicks ! 3 1 Quote Link to comment Share on other sites More sharing options...
cam.in.head Posted July 18, 2023 Share Posted July 18, 2023 once checked and sorted as required the factory sender and guage should be all thats needed. a 88 deg thermostat should read around the centre of the guage and a 92 slightly more. 1 Quote Link to comment Share on other sites More sharing options...
Mickfrad Posted July 18, 2023 Share Posted July 18, 2023 I know the voltage stabiliser linked above is relatively cheap. But if your handy with a soldering iron and like to be hands on you can always put your own together. https://www.ebay.co.uk/itm/145079442234?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=ZdL3MOOSQ92&sssrc=4429486&ssuid=6uKliTfERMK&var=&widget_ver=artemis&media=COPY Three pins 12.5-30 volts in, ground in the middle and 10v out. I did one before for a triumph spitfire 1 1 Quote Link to comment Share on other sites More sharing options...
Jessopia74 Posted July 18, 2023 Share Posted July 18, 2023 That’s really great Mick, cheap as you like and as you say not hard. Only thing I would add a small cap in that, say 0.1µF Quote Link to comment Share on other sites More sharing options...
Jonathan Pounsett Posted July 18, 2023 Author Share Posted July 18, 2023 My first thought was “what’s the point?” It seems a really cheap part - then I opened the link….. £3.49 and some odd bits of wire and 3 connectors that we all have lying around. Too late but thanks anyway and hopefully of use to others. 👍 3 hours ago, Jessopia74 said: That’s really great Mick, cheap as you like and as you say not hard. Only thing I would add a small cap in that, say 0.1µF I put “0.1µF” into my Enigma machine but it didn’t return any results 🤷♂️ Why do you think a capacitor is required, what does it add? Quote Link to comment Share on other sites More sharing options...
Mickfrad Posted July 18, 2023 Share Posted July 18, 2023 Found the original link, and it does mention an optional 1000ohm resistor. http://www.britishv8.org/Articles/Voltage-Regulator.htm 2 Quote Link to comment Share on other sites More sharing options...
Sutty2006 Posted July 18, 2023 Share Posted July 18, 2023 There’s waaaaay too many digital futuristic mathematical equations going on in here to justify saving a fiver 🤣🤣 2 Quote Link to comment Share on other sites More sharing options...
cam.in.head Posted July 18, 2023 Share Posted July 18, 2023 i built one for mine using a carlton /senator unit. this was a tca700y which was the std fitted unit from the 83 carltons onwards within the revised dash. using a 10ohm line resistor as fitted . datasheets seem to suggest it works from 12v whereas the 7810 appears to be 12.5 volt minimum ? pin configuration is opposite but works well. plus as usual you get the satissfaction that YOU have built it ! 2 Quote Link to comment Share on other sites More sharing options...
Jonathan Pounsett Posted July 19, 2023 Author Share Posted July 19, 2023 20 hours ago, Sutty2006 said: There’s waaaaay too many digital futuristic mathematical equations going on in here to justify saving a fiver 🤣🤣 19 hours ago, cam.in.head said: i built one for mine using a carlton /senator unit. this was a tca700y which was the std fitted unit from the 83 carltons onwards within the revised dash. using a 10ohm line resistor as fitted . datasheets seem to suggest it works from 12v whereas the 7810 appears to be 12.5 volt minimum ? pin configuration is opposite but works well. plus as usual you get the satissfaction that YOU have built it ! Too late to make one now anyway - mines arrived. I can’t see a capacitor on it; Quote Link to comment Share on other sites More sharing options...
Jessopia74 Posted July 19, 2023 Share Posted July 19, 2023 1 hour ago, Jonathan Pounsett said: Too late to make one now anyway - mines arrived. I can’t see a capacitor on it; It would be a nice to have rather than necessity. For the cost and hassle of adding anyway imo. Quote Link to comment Share on other sites More sharing options...
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