headlights burned out

[daveymc29]

This car is new to me and the owner had passed away so the son knows very little about it, that means I know even less about its history. Car drives will, has a head with a large B on it, seems to be quite powerful, climbs the hill by my house really well. Maybe 4:11 gears, but that's not todays discussion. I had high and low beam lights, went for a drive and while out dipped the lights for oncoming traffic, now I have only high beams. The low beams burned out. I took the lens off and the bulbs are quite hot to the touch. I checked the connections and see that the lights are wired directly into the bucket and directly to the bulb holder, so the wiring is not stock. Several other bulbs on the car don't light and don't appear burned out, but perhaps they are. I'll have to go through this and see. If they are burning out, what should I be looking for first and foremost? The system is 6V positive ground with a generator and cutout as original, or so it appears.

[1931 flamingo]

With lights off how many amps are you showing??
Paul in CT

[Will N]

It's telling that both bulbs burned out simultaneously. Does the wiring system on the car have any kind of fuse in it? You say the bulbs were hot. Did you feel the wires going to the headlights? Were the wires hot too?

Wiring directly to the bulb holder takes out one of the major weaknesses in the Model A wiring scheme. Those original spring loaded connectors where the conduit connects to the bucket are a short circuit waiting to happen- particularly with the repro wires that are available.

I'm thinking, particularly if you don't have a fuse that could have blown, that you have a short somewhere in the low beam wiring, and I'd bet that those wires are hot to the touch. Another thing that can blow bulbs out is an over happy generator, but since your high beams work, I think we can rule that out.

[Mitch//pa]

ck for power at the appropriate spots according to the diagram. you can use a simple 12v testlight to do this... i like starting at the END of the juice that would be the headlight area...
also ck your charging rate to see it is not to high.....

[Kevin in NJ]

Couple of things to consider, I do not know the exact solution.

First, what is the number on the bulb, is it correct?

The voltage regulation in the car is the battery. If the battery pops out of circuit for a moment then the voltage will spike and often takes out the bulbs, well all the bulbs.

Knowing how many cars are, I would suggest that you work on clean and verify every electrical connection. This is a basic procedure you should do with every new to you car. I have seen some pretty interesting electrical solutions in my time. Dirty sockets, poor ground paths all can cause issues. An extra hot bulb becuase of a dirty socket might contribute to a failure, especially with a sudden bump. When I say verify all the connections I mean to look at the crimp connectors and make sure all the strands are connected. Often there are a few broken strands and that will cause a hot spot on the wire.

[Anteek29]

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I would start with checking the battery connections...at both terminals and also at the frame ground connection and generator output terminal. If these are not tight then the generator voltage will rise and burn out the bulbs.

[Tom Wesenberg]

With the engine off and lights on, how many amps discharge does the meter show?

Does the taillight work in both HI and LOW position?

[Mitch//pa]

ck the charge rate output with an analog meter not digital as they usually give false readings on an A... this could give you an indication of a poor battery connection if abnormally high.

[Tom Endy]

Originally Posted by Anteek29

I would start with checking the battery connections...at both terminals and also at the frame ground connection and generator output terminal. If these are not tight then the generator voltage will rise and burn out the bulbs.

Very good advise. The most neglected is the ground cable connection to the frame. It is out of sight, out of mind, and hard to get to. Remove the floor boards and remove the battery. Remove the ground cable from the frame and clean the raised boss until it is shiny metal. You are likely to find, rust, corrosion, powder coating, and paint. Wire wheel the cable, the nut, and the bolt.

When you lose the ground at this connection the generator does not see the battery and the voltage increases and burns out lights and overheats ignition coil.

Tom Endy

[Brentwood Bob]

Dave, when you look at the ground to the crossmember consider adding an auxillary ground cable over to the transmission. The 31 doesn't have engine pans. I don't think this type of maintenance was done for a number of years on the coupe.
Also, take a look at the aftermarket ignition switch and connections on the back of the amp meter. I don't remember the wiring harnesses being replaced. Loose connections are possible. Right?
Bob

[ian Simpson]

As someone who also suffers from Lucas the Prince of Darkness with my MGB, check every ground in the system. Luckily not too many on a Model A. As per Tom Endy et al especially check the major grounds between battery - engine - frame.

I had a similar problem with exactly the same symptoms on a 1988 Dodge minivan that I bought brand new. It turned out to be a loose bolt on the frame to motor ground connection.

Ian

[daveymc29]

The amp meter is above 10A while driving with nothing on. I know that isn't a good thing. I have been driving for a couple of blocks and up a steep hill with speed bumps to try to get a feel for the car and how far I want to delve into it. Seems to me to have plenty of power. What's that head with the large "B" on it? (Must be two inches tall, the "B," Not the head.) I'm hoping to change out all the fluids and replace the wiring, I have the full set, but some of the bullets and receptacle pieces are missing. Making up an order now and will add to it through the next few days, I do have a new ground strap and will go digging when I get time and it warms up a tad. I'm getting old and the cold hurts me more than it used to. Can't skinny dip in lake Tahoe now days.

[daveymc29]

Bob, I have the wiring for all the system, but the light buckets aren't all there. Just a couple of things missing I believe. Probably dropped off as they made the direct connection to the bulb sockets.

[Bob C]

You have the high compression police head, 5.22:1 compression ratio.

Bob

[Mike V. Florida]

What year is the car? Did you have High, Low, and parking lights when you got the car?

[Brentwood Bob]

Pm sent.
Glad to hear you are enjoying the car. That is the quietest drive train I have ridden in, and the first police head I have seen.
I have a box full of new repo harnesses if needed, might check the brake light switch for shorts.
Bob