QuestionQUESTION: I have 1977 MGB I bought new in 1977. It has been sitting in the garage since 1999 when it was returned from the repair shop because they could not figure out how to get it to idle smoothly.
About a month ago I put a new battery in it to see if I could figure out the problem. When I turned the key, nothing happened at all. Remembering Lucas’ wiring reputation I held the key in the on position and after about 20 seconds it began to turn over. Every time I tried to restart it I would get the same long delay, like I was fighting a corroded wire problem or loose connection. I checked connections and they are all tight, but I don’t know how to do electrical value readings. I did replace the manifold gasket, finding that the mechanic had put the air vent heater cover behind the manifold instead of in front so it was leaking.
When I went to start it, nothing, but the sound of the key buzzer (which buzzes when I put the key in even if the door is closed????). I realized I had let the battery drain so I decided to jump start it. In the process of hooking things up I accidentally touched the hot side of the jumper to the hot side of the battery and also against the steel opening around the battery, causing a Guinness Record arc, momentary, but large. (from the system on my V-8 North star while running). In the process of diagnosing, I found some of my gages are not working and I think that may be my voltage regulator. What I need is a tick list of things to check and what readings I should have and what is the most likely place to check first. Is there a checklist that starts out with.....after arcing the hot side to the ground check this...then this...
I did also install a small round black relay on the wheel well wall and it clicks when I try to start the car. How do I check if I installed it correctly? It the one closest to the firewall that has 4 terminals. One copper and three tin. I appreciate any assistance you are willing to extend.
Thanks
Jim
ANSWER: Hi Jim,
I found that when I had multi electrical problems like you have I had to pick one and only one circuit to test and forget there are other issues until you correct the one.
If it were to come to me in a shop I would concentrate on the starting problem only.
The delay in starting like you are getting can be a bad connection and by holding the key in the start position and it slowly starts the engine turning is a common symptom of a poor connection. So have someone hold the key in the start position and be careful but feel every connection from battery to solenoid to engine ground strap to battery ground cable. Feel the ends of all connections and cables in the complete circle. If it is a bad connection, it will get hot so don't get burned. If that don't net you the problem, you will need a volt meter to do "Voltage Drop Tests" on the cables. If you are not familiar with drop tests put the volt meter on a low DC volt scale and put one probe on the positive post of the battery (not the cable end) and the other probe on the starter solenoid post (not the cable end) (you will need a long piece of heavy gauge wire (12 ga) to use as a jumper as most test leads are not that long. Then try to start the car, you don't need to hold it long like you have been. You should see very little voltage. If you see several volts or more you have found the problem. Next do the same test from the engine block to the car body and hit the starter again. Then check from the engine block to the negative post of the battery (not the cable end) Each time you should see less then a volt.
If all is ok put the volt meter on a scale to read 12v DC and put the volt meter across the posts of the battery and read battery voltage and while it is connected hit the starter and read battery voltage.
Let me know each and every reading you get.
Howard
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QUESTION: While reading other answers you have provided I discovered I had the relay for the starter solenoid wired incorrectly. In looking for the voltage problem I started by feeling different connections and found a very small disconnected wire going to one of the posts on the starter. In checking for hot wires, the first wire was the main cable from the battery to starter. It got hot. In checking the voltage drop the first reading was 3.2 on the red cable coming from the battery to the starter. I put a red jumper cable between the two and got a 12.7 reading. I then left the jumper connected and tried starting and it started right up. I now have to read how to set the correct idle and recheck the timing. It is running at about 2200 RPM's. Hopefully you have answered that problem for someone else. (I had to remove the carb and the accelerator linkage to fix the manifold gasket, so I am sure the adjustment is somewhere in what I had touched.) The other problem I have is the fan switch will not engage the fans. If you hook a wire between the connector ends, they turn on and rotate counter clockwise. The switch is new. I bench tested it for continuity by holding it in a plastic covered vise and reading open and closed by heating it gently with a torch. If I did this again, and touched a meat thermometer to the switches outside surfaces, would that be enough of a guide to tell if it is opening at the proper temp? Do you know the proper temp? Or is it listed somewhere? Does the coolant fluid level affect the fan switches function? How do I tell if the thermostat is working?
AnswerJim, disconnect the throttle linkage to see if that is holding the throttle open any. Then check to see that the choke is off and the fast idle is off. If all that is ok slowly restrict the air going into the engine with your hand and if you keep restricting the air flow and the engine speeds up any, you still have an air leak somewhere.
As for the fan thermostat, it starts the fans at 200 deg F. and turns them off when the temp drops below 180 deg F.
You should not operate the engine when the coolant level is low, it can effect the engine and the engine thermostat and everything.
