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Quirky engine light

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jaybird

jaybird

Yoda
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This has been going on a week or two, haven't been driving Emma much, so I can't put an exact date on it.

Once started (that's another thread) and she's cold, the engine light stays on. Even though I have good oil pressure, 70#. After 5 minutes or less, the engine light will go out, AS LONG as my RPMs stay up. If I coast or drop her down a gear, or come to a stop, the engine light comes back on as soon as the oil pressure drops below, 55-52#. Then goes off again once I'm up to speed and the pressure is back up to 70#. I have noticed the oil pressure seems to drop a bit lower than in the past, down to 25# or so at an idle or stop.

But overall, she's running great and the pressure is steady at 70# when she's going.

???
 
check fan belt to see if its tight
 
It is, was first thing I checked the other day. Tight, no cracks, no glazing, was put on new in August.
 
[ QUOTE ]
It is, was first thing I checked the other day. Tight, no cracks, no glazing, was put on new in August.

[/ QUOTE ]



You're NOT supposed to use Nylons as the fan belt for long term. Of course you know that right?


OH, were you gone for a while? /ubbthreads/images/graemlins/grin.gif


Paul
 
Never nylons. Only stockings with lace garters.

Get out in the garage and do something productive Paul.
 
Isn't the "engine" light in fact, an "Ignition" light.

Although an "ignition" light has (almost) nothing to do with the Ignition.

It is in fact a sort of Amp Gage that turns red when the needle deflects either + or -.

That being said, my first suspicion would be the dynamo & or regulator.

The light should go off just above tick-over
 
Little round red light on the dash, I just call it an engine light, because if the engine is off, it's off, if it's running, it's off, and if it's going to die, it comes on.
/ubbthreads/images/graemlins/grin.gif

Until last night, for the past week or so, was coming back on when the oil pressure dropped below 55 or so pounds. I know that light doesn't gauge my oil pressure, but there's some connection somehow. Went back off after pressure was over 55#.
 
The higher your RPM's the higher your oil pressure AND the higher the output of your alternator.

Your alternator should not have to be going that fast to make more than enough power.

(point in which the light goes out)
 
That's why I think it's an alternator problem. I'll test the battery later this afternoon. I'm thinking the alternator is bad/shot and I was running on battery last night. When the battery got low, I didn't get enough spark to keep me going.

Am checking the ignition circuit from the condenser back as well.
 
You're on the right trail JB. Also check the electrical connections on the alternator to make sure they are not loose or corroded. I've also heard but never experienced the fact that if that light isn't working, the alternator won't have an control signal. So I guess what I'm getting at is if alternator checks out, battery good, belts are tight, connections clean and tight, it might be worth the effort to check the connections at the harness for that light up inside the dash. Not sure on that but it seems logical to me anyway.
JC
 
When the light is on, it is your car's electrical system telling you that it is not in a state of equilibrium.

Imagine a tug of war between your battery & alternator. When the battery is providing more power than the alternator the red light comes on. (Ign on, car not running/ alternator not turning)
When the alternator is making more power than the battery is designed to take, the red light comes on. ( a rare overcharge condition when the regulator goes goofy)

That being said, whenever the light goes off, the alternator & battery are making (essentially) the same amount of power.

All is right, harmonious & in a state nirvana
 
agreed, the light is more of a charge light than a "engine problem light". It'll come on if the battery is low or if the alternator output is low. If it's only lighting brightly when you're not moving or at normal idle, then it's likely the alternator dieing on ya.
 
Keep in mind that you can run a car for miles & not have enough juice to start it.

Your 3 biggest current users are 1) STARTING 2) headlights & 3) horn

One toot of the hooters is enough to run your car's ignition for a miles.
 
I like the "tug of war" analogy there, Dave.

You're gifted. /ubbthreads/images/graemlins/devilgrin.gif
 
Nirvana = rode home today with the top down...oh and no charge light either. Converted to a GM alternator last year.
JC
 
Submitted for the approval of Dr Disorder.............. /ubbthreads/images/graemlins/grin.gif


One lamp wire is connected to the smoke storage device & the other to the smoke governor.(in charge of smoke production)

The lamp is illuminated when there is a smoke pressure differential.

Taking into account that the bulb leaks a bit.
 
my light in my 74 midget stays on and gets brighter when revved...would this be the alternator then? it puts out
13.6 volts when revved........
 
possibly due to poor connections between the battery and alternator?

The voltage at the battery terminals should be the same as at the alternator if all the connections are good and solid, even if the alternator puts out 14v when rev'ed.

I'm not sure about Midgets, but the light comes on in Bs when there is a voltage differential between the alternator output voltage and the battery voltage. There would only be a voltage difference between the two if there's a dirty or bad connection in between.
 
Figured out why the multimeter wouldn't work. Dead battery.
/ubbthreads/images/graemlins/grin.gif
 
Sigh, I've done that.
 
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