McMuttley Posted November 30, 2016 Author Report Share Posted November 30, 2016 Hi H, I have 'fallback friday' (see what i did there!) booked with the local mechanical wizard, but didn't want to leave it too late. In any case, its the challenge of restoration that picks me up (and throws me down). I also suspect that there is more expertise here than in the back of a van ! Yours Apprentice McMut Quote Link to post Share on other sites
Lebro Posted November 30, 2016 Report Share Posted November 30, 2016 Agree with RobH, It now sounds like the problem is the white wire from Fuse box to coil. possibilities are: wire broken part way along (most unlikely) bad connection at the push on connector (either end) Thirdly, I see you have a lot of extra fuses above your standard fuse box, also that you have some white wires going to two of them Could your car be modified to fuse the coil circuit? if so, it could be one of the 10A fuses blown ? Do you have a wiring diagram specifically for your car ? By the way, the "silver thing" you refered to earlier is the overdrive relay - not relavant. Bob. Quote Link to post Share on other sites
billy l Posted November 30, 2016 Report Share Posted November 30, 2016 (edited) Disconnect the white wire at the coil, substitute it with a jump wire from battery (power terminal not the earth) to the coil then try to start, if it starts the problem is in the supply somewhere. Cheers, Bill. Edited November 30, 2016 by billy l Quote Link to post Share on other sites
RobH Posted November 30, 2016 Report Share Posted November 30, 2016 "Disconnect the white wire at the coil, substitute it with a jump wire from battery (power terminal not the earth) to the coil then try to start, if it starts the problem is in the supply somewhere. Cheers, Bill." Fine as long as he realises the only way to stop the engine again will be by pulling the jump wire off. We know from tests Austin has done that there is switched power at the A3 fuse terminals so better to jumper from there I think, then he can switch it off normally. Quote Link to post Share on other sites
Lebro Posted November 30, 2016 Report Share Posted November 30, 2016 +1 Quote Link to post Share on other sites
Guest ntc Posted November 30, 2016 Report Share Posted November 30, 2016 My money is on the Aldon. Quote Link to post Share on other sites
billy l Posted November 30, 2016 Report Share Posted November 30, 2016 (edited) +1 for the above, Rob & Bob by coming direct from the battery you eliminate any possible faults from other connections, even if there is power at A3 how do we know this is not intermittent? Also how difficult is it to pull the wire off the terminal? Cheers, Bill. Edited November 30, 2016 by billy l Quote Link to post Share on other sites
Ian Vincent Posted November 30, 2016 Report Share Posted November 30, 2016 Austin, If you know you have 12v at A3 then I would run a separate thin wire from A3 to the coil and see if it will start before going any further. I suspect it will start so you can then run that wire as a permanent connection and disconnect the existing. The extent to which you disguise what you have done for your viewing is up to you. Yes it is possible that one of those blade fuses in the block above is looped into the ignition circuit somewhere but I doubt it and anyway it is possible to check if any are blown by pulling them out and inspecting them. Also for future reference it is possible to buy blade fuses with an LED in them that lights up if they are blown, because they are the ones I use in my car. Rgds Ian Quote Link to post Share on other sites
graeme Posted November 30, 2016 Report Share Posted November 30, 2016 The white wire is prone to breakage inside the insulation at the Lucar terminal on the coil. Check there. Cheers Graeme Quote Link to post Share on other sites
roy53 Posted November 30, 2016 Report Share Posted November 30, 2016 my favourite would be the competition master cut of switch i be leave you have fitted. Try taking a wire direct from the + on the battery to the coil then flick the points to check for spark. ROY Quote Link to post Share on other sites
Grahamgl Posted November 30, 2016 Report Share Posted November 30, 2016 From Austin's under dash pic.it would appear he, or a previous owner, has a liking for blue crimp on connectors. If there is one on the coil end of the wire from A3 then that could well be the culprit. Graham Quote Link to post Share on other sites
Ian Vincent Posted November 30, 2016 Report Share Posted November 30, 2016 my favourite would be the competition master cut of switch i be leave you have fitted. Try taking a wire direct from the + on the battery to the coil then flick the points to check for spark. ROY In one of his earlier posts Austin says he has power to terminal A3 but zip at the coil which suggests it won't be the battery master switch. The latter would cut off all power and he would have nothing at A3. Rgds Ian Quote Link to post Share on other sites
McMuttley Posted November 30, 2016 Author Report Share Posted November 30, 2016 Graham, how dare you - blue crimps ! FYI they were the work of an MG specialist - need I say more. Anyway, great news...... Break in A3 to coil wire found about 2" from coil end - phew ! Cut dead section out - checked resistance and OK - like 0.3 ish, so crimped and soldered new spade and now we have 12-13 Bloody Beautiful VOLTS to the coil !!!!! Turn over (for just a few seconds) and the points open and close and SPARK !!!!! Placed coil to dizzy HT lead against block, turned over (again for just a few seconds) and it SPARKS !!!!! Put on new TRE supplied dizzy cap and DD red rotor arm, all plug HT leads pulled off plugs to stop firing up and tested a lead// removed plug against block and again (after turning over for just a few seconds) - SPARKS !!!! Obviously at 2047 pm we wouldn't dream of firing up the engine but all seems ready to go ????? (ps - evening nosey neighbour - we could hear you shuffling outside - get a life you sad git 10 -15 seconds total of starter motor in a garage well away from your sad household). So, apart from the pathetic neighbour, all seems OK????? Many thanks to all, advice and diagnosis of what is in the end an 'experience' issue greatly appreciated. However, just one query..... If I read Sri Lankan Bob's original advise correctly, with the points closed we should get 0v and with them open 12v. Closed we get 12v and held apart with a convenient wooden chopstick we also get 12V, but as the rotor rotates, the points open and close and make SPARKS. Do I still have something to check ? Quote Link to post Share on other sites
Ian Vincent Posted November 30, 2016 Report Share Posted November 30, 2016 (edited) Congratulations ???? To answer your last question Austin no. The low T circuit is delivering 12v to the points at all times. When the points are open it can't flow to earth but when they are closed the circuit is complete and current flows through the coil. It is the points opening which breaks the circuit and at that point the magnetic field in the coil collapses instantly which generates a high voltage spike in the HT circuit in the coil. It's that spike that gives you the spark. Rgds Ian Edited November 30, 2016 by Ian Vincent Quote Link to post Share on other sites
tthomson Posted November 30, 2016 Report Share Posted November 30, 2016 It seems to me that there are only a few places the problem can be: 1. If the A3 fuse connections are grubby so it measures 12 Volts with a meter, but has an Ohmic connection. - Clean the ends of the fuse and the terminals it sits in. 2. The white wire from A3 to the dizzy has a break - check at each end that the spade connectors are actually connecting to the wire. Sometimes the wire corrodes or breaks leaving only the insulation holding it in place. I sometimes use a meter on Ohms with the red lead connected to the spade connector and the black lead connected to a pin that I then push through the insulation at various places to check for connectivity from the spade to wire. Better to do this with the wire pulled off the A3 fuse connection. 3. Check the points are opening and closing as the engine turns - Use meter on + side of coil and manually open and close the points then see that this is repeated when the engine turns over. Most problems tend to be from connectors and/or corrosion, or points not set correctly. Don't bother checking the HT side until the LT side is working - it just leads to confusion. Let me know how it goes. Good luck TT Quote Link to post Share on other sites
Lebro Posted November 30, 2016 Report Share Posted November 30, 2016 However, just one query..... If I read Sri Lankan Bob's original advise correctly, with the points closed we should get 0v and with them open 12v. Closed we get 12v and held apart with a convenient wooden chopstick we also get 12V, but as the rotor rotates, the points open and close and make SPARKS. Do I still have something to check ? If you put the red test lead on the white wire side of the coil you will get constant 12V, but if you put it on the distributer side of the coil, it should go down to 0V when points are closed, & up to 12V when they open. Bob. Quote Link to post Share on other sites
Hamish Posted November 30, 2016 Report Share Posted November 30, 2016 (edited) Congrats ???????? what a relief. Fix on Wednesday track day Monday ???? Edited November 30, 2016 by Hamish Quote Link to post Share on other sites
rog1 Posted November 30, 2016 Report Share Posted November 30, 2016 Drive on Monday, complete sale on tuesday?! Quote Link to post Share on other sites
TR5tar Posted November 30, 2016 Report Share Posted November 30, 2016 Anyway, great news...... Break in A3 to coil wire found about 2" from coil end - phew ! Cut dead section out - checked resistance and OK - like 0.3 ish, so crimped and soldered new spade and now we have 12-13 Bloody Beautiful VOLTS to the coil !!!!! Turn over (for just a few seconds) and the points open and close and SPARK !!!!! Placed coil to dizzy HT lead against block, turned over (again for just a few seconds) and it SPARKS !!!!! Brilliant news Austin. I hope all goes well with the sale, but I'll miss Old smokey (and your good self, of course), because I've learnt so much from following your tales of woe here on the forum. Cheers, Darren Quote Link to post Share on other sites
McMuttley Posted November 30, 2016 Author Report Share Posted November 30, 2016 If you put the red test lead on the white wire side of the coil you will get constant 12V, but if you put it on the distributer side of the coil, it should go down to 0V when points are closed, & up to 12V when they open. Bob. Bugger - 12v (13.5V) whether points open or closed, even rubbed W&D between the points and still the same volts both times. Made sure points were probably contacting, but still volts. There are no words into the dizzy other than that from the coil (HT's excepted), i.e. no earths ? Will see friday morning if it fires up ? Quote Link to post Share on other sites
Lebro Posted December 1, 2016 Report Share Posted December 1, 2016 Don't understand how that is possible if you were getting sparks !! The dizzy gets it's earth through the block. Oh well, will wait for todays results. Bob. Quote Link to post Share on other sites
RogerH Posted December 1, 2016 Report Share Posted December 1, 2016 Hi Austin, I'm glad you are selling Old Smokey - your story writing is too much competition for me Roger Quote Link to post Share on other sites
BlueTR3A-5EKT Posted December 1, 2016 Report Share Posted December 1, 2016 Bugger - 12v (13.5V) whether points open or closed, even rubbed W&D between the points and still the same volts both times. Made sure points were probably contacting, but still volts. There are no words into the dizzy other than that from the coil (HT's excepted), i.e. no earths ? Will see friday morning if it fires up ? Would a shorted out condenser cause this issue? - Trial by substitution would be my approach - change ONE thing at a time? On Roger's note.... Perhaps we should all club together and buy 'Old Smokey', then give it back to McMuttley so we can continue the saga? NSF initiative/purchase - a problem car that throws up random faults that can be used as a teaching aid to the ownership. Would it be eligable for TR Gold status? Peter W Quote Link to post Share on other sites
RobH Posted December 1, 2016 Report Share Posted December 1, 2016 No Peter - a shorted condenser would give a 0 volts reading all the time. Since Austin has apparently seen sparks now that the broken wire is fixed, it probably means the meter reading was somehow erroneous. Friday will tell. Quote Link to post Share on other sites
roy53 Posted December 1, 2016 Report Share Posted December 1, 2016 Well Ian break in A3 wire found so no power there. The direct wire would have shown a fault in the wiring somewhere. Quote Link to post Share on other sites
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