electrical gremlins

[wilderb]

ever since a few days ago my 79 620 started not turning over on the first try, I have to wait a few seconds and then try again at which point it will turn over but will struggle to do so, the ground wire on my matchbox dizzy will get hot and actually melt the insulation off, have the dizzy grounded to the battery and have for almost a year. one more thing the motor has wanted to run on even though the key is off, all these things just showed up without any kind of mods to the truck.

 

I will get the battery tested to see if that is the culprit, but if it is would that cause my dizzy ground to over heat?

 

heeelp!!! this is my daly, actually my only running vehicle

[jefe de jefes]

Disconnect the dizzy ground and check your other grounds.

[banzai510(hainz)]

what is your alternator doing by chance?

 

was anything swapped lately?

[DanielC]

Start with this. Clean your battery terminals.

 

Make sure there are good grounds between the battery, the engine block, the cab of the truck, and the bed of the truck, and the frame of the truck.

After 30 years of use, what was once a good ground from the factory could go bad. You may have to add additional grounds. Pay close attention to the alternator connections also. The frame of the alternator must have a ground wire on it. I do not know the details of a 1979 620, but on my 521, there is a factory ground wire from the alternator frame directly to the negative battery cable, and also a factory ground wire from the frame of the alternator to the voltage regulator mounting bolt.

 

You can check for a bad or good ground by doing this. Take a voltmeter, and put the negative lead of the voltmeter on the negative battery post, and the positive lead on the engine block. It should read zero.

I just hooked up a voltmeter on my 521 like I described, and when cranking the engine, got around .150 volts, and when the engine started, and the alternator was charging the battery it initially read about .02 volts, and that dropped off as the battery charge topped off.

[H5WAGON]

Start with this. Clean your battery terminals.

 

Make sure there are good grounds between the battery, the engine block, the cab of the truck, and the bed of the truck, and the frame of the truck.

After 30 years of use, what was once a good ground from the factory could go bad. You may have to add additional grounds. Pay close attention to the alternator connections also. The frame of the alternator must have a ground wire on it. I do not know the details of a 1979 620, but on my 521, there is a factory ground wire from the alternator frame directly to the negative battery cable, and also a factory ground wire from the frame of the alternator to the voltage regulator mounting bolt.

 

You can check for a bad or good ground by doing this. Take a voltmeter, and put the negative lead of the voltmeter on the negative battery post, and the positive lead on the engine block. It should read zero.

I just hooked up a voltmeter on my 521 like I described, and when cranking the engine, got around .150 volts, and when the engine started, and the alternator was charging the battery it initially read about .02 volts, and that dropped off as the battery charge topped off.

 

Im sure you meant to say, turn the volt-meter to ohms when doing the grounding test....:D

 

 

If testing volts put one lead one the + side of the batt and the other lead to the motor block , you should get 12

 

Also could have an issue with switch on back of ignition lock..?

[wilderb]

what is your alternator doing by chance?

 

was anything swapped lately?

 

 

So I charged the battery overnight and it still does the same thing, but when I use my booster pack the c truck fires up right away.

 

nothing has been changed, so I don't know what could cause this to happen, I will try to get a new battery to see if it gets better, I still don't know why it runs on now though

 

anyway I am baby sitting now so I won't be able to get to it till later

[DanielC]

No, I did not mean Ohms. The volt meter is essentially shorted by the negative battery cable. I am not testing the volts of the battery, I am testing the connection between the negative battery post, and the engine block. Any poor connection will read low ohms, but when you make current flow through the connection, the AMPS flowing will cause a slight voltage drop. The worse the connection, the greater the voltage.

 

Read this. It will explain voltage drop testing better.

http://www.vernco.com/Sparks/id606.htm

 

WilderB, did you clean your battery terminals?

[wilderb]

No, I did not mean Ohms. The volt meter is essentially shorted by the negative battery cable. I am not testing the volts of the battery, I am testing the connection between the negative battery post, and the engine block. Any poor connection will read low ohms, but when you make current flow through the connection, the AMPS flowing will cause a slight voltage drop. The worse the connection, the greater the voltage.

 

Read this. It will explain voltage drop testing better.

http://www.vernco.com/Sparks/id606.htm

 

WilderB, did you clean your battery terminals?

 

funny thing, I did cleaned the battery terminals and now it fires right up no prob, I am still taking care of my baby so all I was able to do is start the truck about a dozen times and every time it fired up like it did before the problems started, I hope that all is ok now

 

battery terminals were all black with a little bit of corrosion on positive side, I sanded down to shiny lead and applied a coat of dielectric grease

 

btw I think I might have found the reason why it tends to run on, I had made an air filter out of some air conditioning element and it seems that some if the very thin wire mesh used in the filter media broke off, any ideas on how to expel this stuff out of my cylinders? the stuff is almost paper thin so what I have done so far is rev the sh** out of the engine maybe this will expel the small pieces out

 

thanks to all those that helped, I'll keep you guys posted once I get to drive it