moodoo Posted August 28, 2012 Share Posted August 28, 2012 Evening... This evening was the first time for months that I've had the manta (A-series with GTE injection) out when I needed the headlights on. Strange thing is that she's running hotter with the lights on...normally car would run with temp gauge just to the right of the first gauge mark. With the headlights on this evening she got as far as the second mark. If I turned the lights off, she would go back to 'normal'. It was pretty cool this evening, so there shouldn't have been any reason for her to be running hot, and definitely it didn't run that warm before. I have about 13.5V at the battery when she's running with the lights off, and 13.2V when the lights are on. Took the belt off the alternator, and it spins nice and freely, but can't see what else it could be other than the alternator somehow? Anyone any idea? Fin Quote Link to comment Share on other sites More sharing options...
upk Posted August 28, 2012 Share Posted August 28, 2012 Could be the voltage stabiliser on the back of the instrument cluster! Quote Link to comment Share on other sites More sharing options...
moodoo Posted August 28, 2012 Author Share Posted August 28, 2012 Hmmm..thanks Kev...any way to check the stabiliser out? Would it show up on the fuel guage as well? Quote Link to comment Share on other sites More sharing options...
611 Posted August 28, 2012 Share Posted August 28, 2012 Just what i was thinking. Quote Link to comment Share on other sites More sharing options...
Danny D114BCW Posted August 28, 2012 Share Posted August 28, 2012 I think it can effect different parts on the clocks, not all of them? Quote Link to comment Share on other sites More sharing options...
Brown Job Posted August 29, 2012 Share Posted August 29, 2012 I'd be 100% sure this is a voltage stabiliser thing. They do all sorts of weird things to the panel unless you have one of the modern replacement stabiliser units. For instance, ever noticed that you apparently have less fuel in the tank after you've left the car standing in the sun than you did when you parked it up early morning? Go back and switch on at night and hey presto, the fuel gauge has gone back up again. Also, the fuel gauge reads higher immediately after switching on and driving off than it does a couple of miles down the road when everything has warmed through. Normally, fuel tank and temperature gauges are affected simultaneously with a dodgy stabiliser but you may not have noticed the fuel gauge, or it may be less sensitive to minor shifts. Sadly, only way to check the stabiliser is by fitting another stabiliser. And they are a !$*$$*! to get at! BJ Quote Link to comment Share on other sites More sharing options...
garymanc Posted August 29, 2012 Share Posted August 29, 2012 from a search of the forum........The voltage stabiliser only controls temp and fuel gauges, and can affect those in different ways when it fails. maybe check your headlamp earths as well Quote Link to comment Share on other sites More sharing options...
moodoo Posted August 29, 2012 Author Share Posted August 29, 2012 Thanks for all the input guys! Much appreciated. OK, so as I understand the voltage regulator sends a set voltage to the coolant temp sender and to the fuel level sender. The resistance of both those items changes depending on coolant temp and fuel level respectively. Same voltage but different resistance means different amount of curret flowing, which means the gauage element heats up a different amount, which causes the needle to move. So....if I measure the voltage going to the temp sender with the lights off, and then measure with the lights on, it should be the same. Alternatively I could measure the resistance of the coolant temp sensor (I have injection) when the gauge reads 'cooler' or 'hotter', and see if the resistance has actually changed. Sound right? Quote Link to comment Share on other sites More sharing options...
mantasrme Posted August 29, 2012 Share Posted August 29, 2012 The voltage regulator supplies 10volts to the gauges (fuel level and water temp) not the sensors, that is if its still working correctly. When they fail they allow full battery voltage through so anywhere from 12 to 13.5volts which is why the gauges read high. The sensors are on the earth side of the wiring so aren't affected themslves. I haven't had one that plays up with the headlights on but it wouldn't suprise me thats the cause in your case. You can check the regulator by either removing it and testing on a bench with a 12v supply, or test in situ but you have to remove the cowling and pull the clocks forwards to access the terminals with a voltmeter for that. Oh and with a little practice you can remove and replace a voltage reg without any tools or removing any of the dashboard/ clocks Quote Link to comment Share on other sites More sharing options...
Brown Job Posted August 30, 2012 Share Posted August 30, 2012 Oh and with a little practice you can remove and replace a voltage reg without any tools or removing any of the dashboard/ clocks Yes, that's right you can. I've practiced. But it takes a bit of practice to aquire the ability to hang upsidedown with your feet locked round the headrest, at the same time growing 9 inch double-jointed fingers to get in at the thing. Anyone found another route in? Oh, by the way, there's someone on the Forum (or was) who supplies modern replacement voltage stabiliers. BJ Quote Link to comment Share on other sites More sharing options...
dog321fish Posted August 30, 2012 Share Posted August 30, 2012 http://www.ebay.co.uk/itm/Semiconductor-Voltage-Stabilizer-Vauxhall-Opel-Manta-/280949346889?pt=UK_CarsParts_Vehicles_CarParts_SM&fits=Model%3AManta&hash=item4169e2d249 HTH Dave Quote Link to comment Share on other sites More sharing options...
mantasrme Posted August 30, 2012 Share Posted August 30, 2012 Yes, that's right you can. I've practiced. But it takes a bit of practice to aquire the ability to hang upsidedown with your feet locked round the headrest, at the same time growing 9 inch double-jointed fingers to get in at the thing. Anyone found another route in? I remove the heater duct that goes from the heater control box to the windscreen demister on the drivers side which pulls off and gives much more space to work and see what your doing. Then i pop a cushion/ padded mat across the sill and lay with my head by the pedals looking up, then snake my right arm up and remove the old one more by feel than sight. New one goes back the same way but you normally need a bit of a look to get it into the right place. With a bit of practice its only a couple of minutes to swap them, but i wouldn't recomend it if you have a bad back Quote Link to comment Share on other sites More sharing options...
Brown Job Posted August 31, 2012 Share Posted August 31, 2012 I remove the heater duct that goes from the heater control box to the windscreen demister on the drivers side which pulls off and gives much more space to work and see what your doing. Then i pop a cushion/ padded mat across the sill and lay with my head by the pedals looking up, then snake my right arm up and remove the old one more by feel than sight. New one goes back the same way but you normally need a bit of a look to get it into the right place. With a bit of practice its only a couple of minutes to swap them, but i wouldn't recomend it if you have a bad back I didn't have a bad back until I started trying to hang upsidedown in cars pulling out voiltage stabilisers ... but I think your method sounds better than mine, and less likey to dislodge breakfast as well. Will note for future reference, many thanks BJ Quote Link to comment Share on other sites More sharing options...
moodoo Posted August 31, 2012 Author Share Posted August 31, 2012 OK, thanks a lot guys. Anyone know if that stabiliser listed on ebay is suitable for the A and the B, is there any difference? So there's no easy way to test without getting access to the thing itself? Darn. I have a bad back already, don't fancy making it any worse! If I do manage to get it out, I give 12v on input and see what I get out the other? (I've since realised that I have a blown main bulb, which might be causing some wierdness?? Anyway, when I get a chance to look at her I'll report back.) Quote Link to comment Share on other sites More sharing options...
mantasrme Posted September 1, 2012 Share Posted September 1, 2012 You can access it in situ by removing the cowling and pulling the clocks towards the steering wheel a bit, then there is enough room to get a voltmeter probe in to see what voltage is coming out. There are 3 pins on the regulator and the middle one is the output that should be 10v when checked to earth But to be honest if you're going to pull the dash out to check it i'd just order one of the new voltage regs from e-bay anyway and change it while your at it. That way if its faulty you can fix it straight away, and if its not faulty you can pre-empt its eventual failure with one that won't fail. Quote Link to comment Share on other sites More sharing options...
moodoo Posted September 1, 2012 Author Share Posted September 1, 2012 Yes, thanks, sound advice...you're right, might as well do the job while I'm in there! Quote Link to comment Share on other sites More sharing options...
moodoo Posted September 3, 2012 Author Share Posted September 3, 2012 OK, so an update and a question. Got the stabiliser out OK (removed the clocks, so it wasn't so bad, and no back twisting required!), and put 12v DC across the 2 outer pins. Measured the voltage output between the centre pin and earth. It read 7.5V for maybe 10 seconds, then started jumping all over the place...-4.5v back to 7.5v and everywhere in between. Am I testing this incorrectly, or is the stabiliser completely screwed? Quote Link to comment Share on other sites More sharing options...
manta88 Posted September 3, 2012 Share Posted September 3, 2012 There is a bi metalic strip inside the regulator,when it warms up it will start turning on and off which is what you are reading, it would have given an average voltage of ten volts 40 years ago.I have had a ten volt regulator on my GTE for many years,i'm sure the a's and b's are the same so the ones on ebay should be ok. Quote Link to comment Share on other sites More sharing options...
Brown Job Posted September 4, 2012 Share Posted September 4, 2012 Well I never did - a bi-metallic strip? No-one ever told me how the damned things worked - I just assumed it was black magic! BJ Quote Link to comment Share on other sites More sharing options...
plumster Posted September 5, 2012 Share Posted September 5, 2012 Are we talking about this thing as a replacement? http://www.ebay.co.uk/itm/Semiconductor-Voltage-Stabilizer-Vauxhall-Opel-Manta-/280949346889?pt=UK_CarsParts_Vehicles_CarParts_SM&fits=Model%3AManta&hash=item4169e2d249 In the vehicle listings it says not compatible for my vehicle... My car runs "hot" supposedly, although i am confident that it is as cool as it should be. Quote Link to comment Share on other sites More sharing options...
mantasrme Posted September 5, 2012 Share Posted September 5, 2012 Yes that is the one, the seller just only lists them for Opel Manta rather than also listing for Vauxhall Cavalier. Quote Link to comment Share on other sites More sharing options...
plumster Posted September 5, 2012 Share Posted September 5, 2012 Smashing thanks. Quote Link to comment Share on other sites More sharing options...
moodoo Posted October 4, 2012 Author Share Posted October 4, 2012 So...I bought one off ebay, it puts out 10V...lovely...fitted it...but now my gauge is reading high all the time! It goes to 3/4 mark even before the thermostat opens. Now since it's putting out 10V instead of 7-ish V, there's more current going through the gauge, so I guess it makes sense that it would read higher, but I can't imagine standard running position should be 3/4? I've used an IR gun on the rad and hoses, and am not getting anything higher than about 80-85deg My car is an A-series with GTE injection, so I'm wondering if the original standard A-series sender is different to the one fitted to GTE? If the resistance of the standard A-series sender was higher, that would bring the gauge back down a bit. Was it just luck that meant that the lower voltage coming from my old stabiliser was keeping the gauge low? Anyone have an A-series sender they could measure the resistance of? Quote Link to comment Share on other sites More sharing options...
Brown Job Posted October 4, 2012 Share Posted October 4, 2012 Well, that's not your stabiliser causing the problem, as the gauge reading comes on BEFORE the 'stat opens. Do you have a problem with the wires/temperature sender, as you suggest? Is something tending to short out? Does the temperature gauge drop back to zero when you pull the connector off the 'stat housing? I might be tempted to replace the wire between the sender and gauge (even just a temporary run of wire) in case the old wire is breaking down from sheer age. They do get very stiff and brittle in the insulation near the constant heat of the 'stat housing, maybe some of the wire strands have snapped through inside. BJ Quote Link to comment Share on other sites More sharing options...
Retro Power Posted October 4, 2012 Share Posted October 4, 2012 I've always had issues with manta temp gauges reading various readings that one might not consider "normal" I (on my own cars) have just either decided what was "normal" and only worried if it changed from there, or soldered a resistor into the wire to get the gauge to read where you want it to!! lets not forget, its hardly an F1 engine, if it gets too hot, it'll chuck its water out to remind you! many years ago when I was at uni I once had the stat stick on my GTE to the point where it went off with a bang when it opened (I only noticed that the gauge was off the end at that point!!) and let the steam out of the head, Never hurt it though!! Quote Link to comment Share on other sites More sharing options...
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