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Post by dave1800 on Dec 1, 2013 3:59:43 GMT
Thanks for the Lucas humour! It makes light or should I say dark reading on a Sunday morning here  I think Tommy has checked all the earths but good to specifically mention those 3 connectors on the firewall which may be accounting for some of the voltage drops. It's strange, my experience with Lucas on Morris 1000s, a Frogeye Sprite, Austin 1300 and several Landcrabs over many years and miles was good. I only ever had 1 coil fail, replace dynamo brushes infrequently and 1 voltage regulator in an alternator. Once I had the lights go out but that was due to a catastrophic engine mounting failure on a Mk111 1800 which resulted in the wire pulling off the connector, so not really down to Lucas. Perhaps I was just lucky? On the other hand my Saabs had numerous electrical (expensive) problems with alternators (Bosch) and ignition modules (Saab and Bosch)and hall ignition triggers. David I've had problems with the connectors in the firewall being corroded, the 3 connectors next to the voltage regulator. Cleaned and reassembled and solved many problems. Somewhere you have a bad ground, or maybe the main ground. I've seen on may cars that have a ground issue the throttle, choke, or heater cables become the ground to the motor. Below is a good explanation of the Lucas electrical system: Guide to Fuse replacement Lucas the Prince of Darkness Also take a look at Haynes the manual humor page www.mez.co.uk/lucas.html |
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Post by Penguin45 on Dec 1, 2013 21:15:34 GMT
Agree with David - most of the issues I've had to deal with (in many vehicles - not just 'Crabs) are caused by previous owners messing. The current work van was a bargain because the fella couldn't sort the electrics. Took me a day and a Half to sort it, but I did. Then of course there are the moments of complete incompetence which are self inflicted........  Chris. |
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Post by charlypm on Dec 2, 2013 4:31:03 GMT
I had a problem in my MGB one time, the fuel pump would cut out. My wife and I were on a trip to California and had the trunk packed. When the fuel pump quit, I'd move items in the trunk and tap on the fuel pump and it go. I stopped and had a fellow in a service station check the points and they seemed fine. As I was driving in the evening I saw my lights go dim, I immediately knew it was a ground, went to the trunk and found a cluster of ground wires wire not grounding to the body. Strange I thought I tightened them down after I got back from the paint shop. Every time I got into the trunk I bumped those grounds and it'd run for a few hours again.  |
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Post by tommydp on Dec 3, 2013 22:45:59 GMT
Hi all!
Great Lucas jokes btw! It seems the jokes are even more relevant to modern, reproduction parts sold in the green Lucas boxes. Fiddling with the new ignition switch today, I noticed the ignition therminal was loose on the copper rivet. Crap! Not exactly what you need when you're checking the whole damn car for voltage drops and bad connections and so on.. On the subject of Lucas, I can't say I've had any trouble with Lucas systems in any cars.
Anyway, I found a spare ignition switch among my spares, and there was no voltage drop across it, so installed that one rather than the original one which is worn and shows drop. Ypu have to wiggle the key in the ignition position..
It actually seems like I'm doing progress. I've rewired: feed from battery + to ignition switch, from ignition switch to coil +, from ignition switch to fuse therminal. I rechecked the voltage drop at coil + and it was still 0.1 V (used to be 0.9 V). I then put the fuse in and tried the brake lights and indicators and noticed instant improvement as the ignition and oil pressure lamps did not dim like they used to. I measured the voltage drop at the fuse as well as the coil againg and they were all 0.1 V or less.
Will have a look at the heater and wipers later. I really think this work is well worth it and I regret I haven't changed the ignition related wires earlier, or paid more attention to the art of checking voltage drops. I'll definitely do the same thing to the blue one later.
Regards, Tommy
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Post by Penguin45 on Dec 4, 2013 0:56:55 GMT
Any progress is good progress, Tommy. If, like so many people, you are scared of the electrics, you finish up with an electrical system which basically hasn't been touched for 40 years. All the basic things you are working your way through are improving the system, even if the results aren't immediately obvious - it will be worth it and the results will probably see the car through another 40 years.
Chris.
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Post by dave1800 on Dec 4, 2013 8:54:55 GMT
Hi Tommy! You are an inspiration to all those who run away from electrics . Once you get into it, you don't need much equipment and it can make the car far more reliable for little money. Do tell us about the heater and wiper experiences in due course. Regards David I really think this work is well worth it and I regret I haven't changed the ignition related wires earlier, or paid more attention to the art of checking voltage drops. I'll definitely do the same thing to the blue one later. Regards, Tommy |
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Post by tommydp on Dec 4, 2013 9:18:27 GMT
Thanks guys! I reckon the work is well worth it, easy work once you know what to fix or rewire and new wires and connectors are cheap. After all, it's ok winter work as the cars are just standing anyway. Don't want to get them near the dreaded salt..
I'm looking forward to investigate the rest of it. By all means, I don't really care if the heater makes the engine run on as I always turn everything off before stopping the car. I will however eliminate anything that might contribute to ignition trouble etc and have as little voltage drop as possible in the ignition switched circuit. While at it, I'll go throught the lighting and other circuits too.
Perhaps getting rid of the voltage drop at the coil will make some improvement too. I've cleaned the engine earth strap connections too and added an extra earth strap straight to the battery. It seems I got a better HT spark, as there is a blue white spark when I open the points now. There was some orange in the spark when I started. I've also changed the HT coil lead, as the original one had unbelievably high resistance.
Hope to continue this afternoon.
Tommy
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Post by dave1800 on Dec 9, 2013 6:08:48 GMT
High resistance in the HT leads WILL lead to premature failure of almost any electronic ignition unit as will pulling off plug leads to see if there is a spark (unless you use a spark tester)as the high voltage has nowhere to go but back through the electronics. I'm sure I've said this before, but no harm in repeating it. David I've also changed the HT coil lead, as the original one had unbelievably high resistance. Hope to continue this afternoon. Tommy |
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I've had problems with the connectors in the firewall being corroded, the 3 connectors next to the voltage regulator. Cleaned and reassembled and solved many problems. 
I think Tommy has checked all the earths but good to specifically mention those 3 connectors on the firewall which may be accounting for some of the voltage drops.
