Voltage issues

[iamtherealJayy]

Here’s a video, it cranked slow then caught then lost it and eventually just stopped. Battery showed 12.6 on multimeter after cranking.

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[mshawn]

It’s me with yet another problem,
1978 Chevrolet K10 bonanza with a 350/sm465/np205.
Just got done reshimming the starter for the 8th time and truck fired right up this morning and fired up again leaving work but I filled up with fuel and it’s a slow slow crank but after a few seconds it’ll slightly speed up and few more it’ll speed up little more and fire once it’s turning over fast enough. I then went home and ate lunch and truck cranked slow again but started after a few seconds. As I crossed the intersection my tach and radio died(only lights on in the truck) and I noticed my voltage gauge was pegged to the right. I immediately pulled over and checked it with a multimeter and it showed 16-17.2 Volts constantly. I sat there for probably 15 minutes to let everythint cool since the ground wire was warm etc then drove home since i was only about a mile and a half down the road. The battery is probably 4-5 years old, alternator I have no idea on age I haven’t replaced it. But my question is, in 78 was it an internal regulator or do I have some alternate regulator somewhere? It’s a 2 wire alternator as far as I can tell with a little plug going into the side. I can get photos if requested but I tried to explain as best as I could.

You my man have a ground problem. The ground cable from the battery to the engine may be corroded inside the insulation, or under where it mounts to the motor, also at the cable mount on the battery. If all those are ok then you have a motor to chassis ground strap problem. On the back passenger side of the head there should be a ground strap going from the motor to the frame, if that is there check for corrosion where it bolts to the frame and the head. Let me know if this helps is not hit me back and we will take the step in the diagnostics. If it is not there order one from and parts store and bolt it on any where safe from motor to frame. I like to sand down both places where they bolt down to where it is bare metal then I bolt the ground strap the paint over them with high temp black paint or what ever color you want.

 

[iamtherealJayy]

Corrosion inside the negative might be possible but I haven’t had this issue until today, the battery cable ends are new the connection on alternator bracket has been redone, I added an 8ga direct battery to frame ground, and redid the head to firewall ground strap. So far none of those have helped anything. I even redid the positive battery cable since it felt warm after cranking, no help.

 

[iamtherealJayy]

The voltage gauge shows 12 before cranking and after cranking but falls on its face during. If the headlights or anything are on you can forget about it even turning over. Does this sound more like a bad battery or a bad connection? I haven’t had the issue until lunch time today.

 

[mshawn]

You want to go to the positive side then . Check amp draw at the starter. If you don’t have a high amp probe you can measure resistance . Go tube you tube and search for voltage drop testing for your starter. Use your voltmeter in these test. This can be don’t on any internal combustion engine. I hope this helps! If not hit me back!

 

[mshawn]

This could either one. Are you able to use a volt meter?

 

[mshawn]

So I had to read read your post. You know how to use a volt meter. I’m telling you to google these Vids because it is easier than me typing this out plus you can use these test on any car. You tube “test amp or voltage draw to test battery.” Then you tube “testing voltage or amp draw for starter or stater solenoid. “

 

[iamtherealJayy]

I’ll have to check into that I knew it was possible just couldn’t remember how to check it. I know how to check ground resistance etc but amps I’m not so familiar with.

 

[mshawn]

You tube is your friend and if I can help more let me know. Also let me know what you find out I’m willing to stay on this with you and help as much as I can.

 

[iamtherealJayy]

I’m watching a video about testint starter draw, the first thing you said to search just showed up how to find parasitic draws leaving you with a dead battery. My battery isn’t dead it just won’t crank. Voltage is fine but amps or somethint isnt

 

[mshawn]

Look for a clip that will show you what kind of amp draw or voltage draw you are pulling on battery while cranking. I don’t think your battery should drop below 10.5 volts while cranking. After that we want to determine the amp draw of the starter while cranking. I think if I can remember right ….. amp draw should be 100 to 150 amps in the standard 350 engine. Hard to remember the correct amps but if you YouTube it I think you will find what your looking for.

 

[iamtherealJayy]

I don’t think my multimeter is capable of testing amperage I don’t have the little clip piece, but I can check voltage drop during cranking to see if the battery is just ready to retire

 

[mshawn]

If you have a lot of amp draw then more than likely a bad connection at the starter or bad starter/bad solenoid. If amp draw is in range and battery dropping below 10.5…. Your battery is more that likely at a bad state of health. Assuming you’ve checked all cables and connections for corrosion.

 

[iamtherealJayy]

Nothing is corroded, starter has <2000 miles on it and all other connections are new. I know my lights dim when trying to crank so I’m gonna try a new battery tomorrow. Any idea about the heat issue in the other truck? Fires instantly cold but if you shut it off when it’s up to temp it cranks slow and won’t start wait 20 minutes and instantly fires again

 

[mshawn]

I can use my snapon triton D10 scanner and clamp my high amp probe to starter positive or the big red wire on alt and see my amp draw as I turn it over, Most voltmeters these days can also. I would YouTube how to use voltmeter to check amp draw on starter, I think someone will show how to do it without the amp clamp.