Diagosing Engine Cranking Issues

Hello,

It is that time of the year. There are lots of reasons that can make a no start situation. But no matter the source of the issue, usually a volt meter is my go to tool. Battery voltage at the posts is a good place to start checking, no load and while cranking the engine. Then the same battery voltage should be at the cable clamps. On 12 volt system it takes a minimum of 9.6 volts at the starter terminal to crank the engine properly. As the voltage drops so does the cranking speed. When the voltage drops low enough the engine will not crank. Having a volt meter is then the tool to have. It may sound simple, but it is. Follow the voltage throughout the circuit. Voltage at the starter is just as important as the amperage coming from the battery. Measuring voltage drop will identify poor-bad connection throughout the circuit,





Guido.

Guido, The First rule of trouble shooting is make sure you have an energy source. My go too tool is a battery conductivity tester. It has a built in voltmeter, but I measure CCA first. No voltmeter can measure battery CCA. What do you use for measuring CCA?

(quoted from post at 06:17:50 01/08/17) Guido, The First rule of trouble shooting is make sure you have an energy source. My go too tool is a battery conductivity tester. It has a built in voltmeter, but I measure CCA first. No voltmeter can measure battery CCA. What do you use for measuring CCA?

Click to expand...

A voltmeter is part of the process a good load tester (carbon pile,voltmeter, amp-meter) does not lie like a conductivity tester will.... I know you are vested into your tester heavy but its not the cats meow.

Geo, do you measure CCA at the starter or at battery?

One of the first posts I made was about how much help a volt meter can be while trouble shooting. By the flogging I recieved you would have thought I cursed the Pope.

One of the first posts I made after joining YT was about how much help a volt-ohm meter can be while trouble shooting. By the flogging I recieved you would have thought I cursed the Pope. The old guard let me know right quick they had been jumping spark,shorting wires and generally flying by the seat of their pants for years and coming in with fancy new ideas wouldn't be tolerated.

The starter tests the CCA!

The old guard prefers to take the long road if that road does not get them to were they are going its trial and error. The old guard will have a fit over this,,, You can read amps with a voltmeter
All the amps the battery are alternator can supply :shock:

Unless I missed it you can not read volts with a amp meter.

(quoted from post at 16:50:36 01/07/17)
Hello,

It is that time of the year. There are lots of reasons that can make a no start situation. But no matter the source of the issue, usually a volt meter is my go to tool. Battery voltage at the posts is a good place to start checking, no load and while cranking the engine. Then the same battery voltage should be at the cable clamps. On 12 volt system it takes a minimum of 9.6 volts at the starter terminal to crank the engine properly. As the voltage drops so does the cranking speed. When the voltage drops low enough the engine will not crank. Having a volt meter is then the tool to have. It may sound simple, but it is. Follow the voltage throughout the circuit. Voltage at the starter is just as important as the amperage coming from the battery. Measuring voltage drop will identify poor-bad connection throughout the circuit,





Guido.

Click to expand...

Exactly . However most mechanics would rather carry a snake instead of holding a voltmeter to a live circuit. They will randomly replace hundreds of dollars in parts hoping to find the problem via random chance instead.

From reading the posts above I think many on YT have no clue what a battery conductivity tester is. It's not a load tester, it's not an ammeter, it does have a built in voltmeter, which clamps on to the battery.

Google conductivity tester to read more. Bottom line a conductivity tester is what everyone that sells batteries or a dealer uses to evaluate the condition of a battery. It's the only thing on the market that can tell you the CCA of your battery, which changes with age, temperature of battery, and the sulfate build up on the plates.

First rule of trouble shooting is to determine if you have an good power source. A dead battery will measure 12v when not under load. After you know you have a good battery, then a voltmeter is esential to determine where the voltage stops. If you have someone to hold a voltmeter on the battery while you are cranking engine, Cranking voltage is helpful. If you work along, better get a conductivity tester.

Hello da.bees,

I guess I may get the same. HE!HEE! But we know what is the tool for the job. Every counterpoint seems to rely on some instruments, and they usually fail to see the obvious! All of those instruments seem to have
a volts readings and a temperature. I guess is not so obvious is it? I presented my post in the most elementary form, because it is. May be some one will actually use the procedure and prove you and me wrong. Can you repost your original one? May be good for a laugh or two. Classic example of KISS........

Guido.

Hello buickanddeere,


Took the word right out of my mouth.....EXACTLY! Little knowledge is the one that speaks the loudest.
I tryed......


Guido.

Hello Geo-TH, In,

My go to tool is my volt meter you should try it! you know why? Its all you need for trouble shooting a no start, low cranking speed issue period. What do you think happens when tbe battery is unable to provide adequate power, V X A, to the starter? THE VOLTAGE AVAILABLE TO THE STARTER WILL DIMISH, and so will the speed. What happens when you drive a 6 Volt motor with 12 volts, voltage beying the only change, voltage at the starter changes, so does the speed. You should know that first hand! What kind of measuring instrument will you use to verify that? Next no start just try using just your volt meter. Place at the right circuit with the right load at the right time, you will find the problem always,


Guido.