15-16V voltmeter?

[83kid]

Hi,
So i replaced my starter today.
Cranked it with the new starter, and voltage drops to 8 volts right away when cranking, let off, it goes back to 13. (according to volt gauge)
Jumped it with another car, other car was running and i hooked up the jumpers and the voltmeter went up to like 16ish when they were hooked up. I cranked it, and it dropped to 8. Eventually after a little while of not wanting to even fire, she started, i got her all warmed up and drove around, and the gauge still reading 15-16V
Also, i found the ground wire going to the radiator support on the passenger side is a little melted on the insulation and where you can see wire, a little corroded, would this have anything to do with it?

why would it do this?

Thanks!

 

[350runner]

I had this same issue year or so ago. Ended up being the positive battery cable.start by changing both battery cables. And take the charging wire on the alternator and run it straight to the positive batt terminal.first go through and "clean all your grounds

Sent from the dust in front of you!

 

[83kid]

Ugh i just had the positive cable off with the starter, was a real pain to get at with the headers i have.
Could this be caused by that ground cable? It's actually quite corroded, but looks like its still ok

 

[350runner]

It's in your case likely a combo of both. You see the corroded insides of the positive and negative batt cable cause it to loss connection with the alternator thus full- fielding. Simple test question do you notice your Windows go up fast?

Sent from the dust in front of you!

 

[83kid]

Whats full fielding?
And, i can't see the positive cable, on the exterior, it looks fine, and it was replaced a couple years ago according to the PO
And, manual windows, so the test doesnt work lol

Thanks!

 

[350runner]

They can " look good" but be bad inside. Hey it could be something else... are your headlights super bright? Heater fan push out lots of air while on high speed?

Sent from the dust in front of you!

 

[350runner]

http://www.freeasestudyguides.com/alternator-full-field-test.html basically the charging system is doing this test on it's own. Not good

Sent from the dust in front of you!

 

[bucket]

It's also a good idea to verify actual voltage with a multi-meter. Unless I misread, all readings were with the factory gauge?

 

[MadOgre]

Positive Batt to starter cables don't really like headers to much either! Make sure the cable is tucked nicely away from those headers

 

[MadOgre]

Simple test question do you notice your Windows go up fast?

Sent from the dust in front of you!

I cant remember, are the windows fed from the same power feed as the lights ?

 

[350runner]

Either way It's going to show the same results if he is seeing that amount of voltage. I'm sure @chengny or @89Suburban is better suited to answer your question... probably could provide schematics too

Sent from the dust in front of you!

 

[83kid]

Oh and also, would the fact that i hooked up the jumper cables going from my other car to the truck have anything to do with it?
At first, it didn't want to start, and had 13 volts normally, then i hooked up the jumper cables, and it jumped up to 15-16 and has stayed that way since.

And yes, all readings are with factory gauge

 

[350runner]

Yea mine did the same didn't want to start. I sent back my year old starter back to summit under the assumption that the starter had list it's torque. Got the new one did the same thing. Changed the positive batt cable and bam back in action it looked great... so I went ahead and changed the rest of the cables and upgraded them all to 4 gauge welding cable

Sent from the dust in front of you!

 

[MadOgre]

Oh and also, would the fact that i hooked up the jumper cables going from my other car to the truck have anything to do with it?
At first, it didn't want to start, and had 13 volts normally, then i hooked up the jumper cables, and it jumped up to 15-16 and has stayed that way since.

And yes, all readings are with factory gauge

If your battery to starter cable is the problem/ not delivering sufficient voltage and amps, Then you hook up jumper cables to your battery, You are still relying on the bad cable to deliver the voltage to the starter, So in reality hooking up the jumpers has not changed the issue, Thus you did not notice any difference in your end result.

 

[83kid]

Yea mine did the same didn't want to start. I sent back my year old starter back to summit under the assumption that the starter had list it's torque. Got the new one did the same thing. Changed the positive batt cable and bam back in action it looked great... so I went ahead and changed the rest of the cables and upgraded them all to 4 gauge welding cable

Sent from the dust in front of you!

If your battery to starter cable is the problem/ not delivering sufficient voltage and amps, Then you hook up jumper cables to your battery, You are still relying on the bad cable to deliver the voltage to the starter, So in reality hooking up the jumpers has not changed the issue, Thus you did not notice any difference in your end result.

Everything was normal prior to putting jumper cables on

The cable wouldn't have "gone bad" in that hour in between putting on a new starter and hooking up jumper cables.
I put the new starter on, it cranked engine and everything, voltage macxed out at 13.
Hooked up jumper cables, as soon as i did voltage jumped to 15 or so, stayed that way since.

Theres a good chance its not the positive cables because of this


And:

Can i drive how it is? Whats bad about it/what can i do?