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How to best diagnose a dying starter?

M

mhopton

NAXJA Forum User
Location
Marietta, GA
So, my 99 Classic, DD, 4x4 that is stock has developed what best can be described as a "slow-to-turnover" condition. Historically, the starter turns the motor very quickly and it lights up fast; however, it seems that the starter is struggling to get the first revolution of the crank turning. Once it's turning, the starter picks up speed and the engine catches. The battery is a 1.5 year old Interstate and I'm getting consistently 14 volts on the dumby gauge - I know that's not the correct way to determine if the battery is good, but just a data point.

How best to eliminate, or identify the starter vs. battery as the problem?

Thanks
 
Curious to hear the responses to this. I have a '99 Classic as well which has developed the same slow first revolution in the past month or two. I however have a brand new DieHard Platinum running mine (as well as upgraded cables throughout) so I think I can rule that out. I was just figuring that maybe after 11 years the poor starter was starting to get tired.
 
Take a set of battery jumper cables and jump from the Plus terminal on the battery to the large terminal on the starter, then see if it cranks the same. Do the same with the Negative terminal of the battery to the block. Just about the only thing that will cause a good starter to go real slow is a bad connection to the battery.
 
For a slow cranking engine, I take a meter reading. With the key in the ON position, check voltage directly at the starter. You should have approximately full battery voltage.

If you do, then the problem is likely the starter itself.

If you do NOT have full battery voltage, then you need to start working your way back into the engine bay to find out why you are experiencing "voltage drop". Can be a bad connection anywhere between the battery and the starter, or ANY ground, or a bad cable.

Good luck!
 
birchlakeXJ said:
For a slow cranking engine, I take a meter reading. With the key in the ON position, check voltage directly at the starter. You should have approximately full battery voltage.

If you do, then the problem is likely the starter itself.

If you do NOT have full battery voltage, then you need to start working your way back into the engine bay to find out why you are experiencing "voltage drop". Can be a bad connection anywhere between the battery and the starter, or ANY ground, or a bad cable.

Good luck!
Click to expand...

You will always read the same as the battery as long as you aren't cranking. You only get a voltage drop when pulling current and if the starter isn't cranking, it isn't pulling any current.
 
Check the connections first. Don't just look at them and call it good. Remove them, shine up the studs on the battery, shine up the connectors, same with grounds, battery to oil dipstick, block to firewall. Put it all back together, fire it up, reset your clock. Go!

If that doesn't work, THEN check the cables themselves.
 
Actually the best way to check for a failing starter is use an amp clamp with a multimeter and see how many amps it's drawing. They spike up quite a bit just before failure.
 
What would be an expected base line amp draw for an OEM starter on a 4.0?
 
FYI, you can use the lower-priced starter from pre-96 XJ's. Just have to splice into the solenoid connector as it is different.
 
old_man said:
You will always read the same as the battery as long as you aren't cranking. You only get a voltage drop when pulling current and if the starter isn't cranking, it isn't pulling any current.
Click to expand...

How about a bad cable as a reason for not having full voltage at the starter? Might not technically be why you usually test for voltage drop, but still a good data point.

I like those meter readings, which don't lie. And take all of 2 minutes.
 
Last edited:
birchlakeXJ said:
How about a bad cable as a reason for not having full voltage at the starter? Might not technically be why you usually test for voltage drop, but still a good data point.

I like those meter readings, which don't lie. And take all of 2 minutes.
Click to expand...
Since the starter isn't being cranked, it is a virtual open circuit. That means that the starter cable could be totally crapped and have one small strand left and it would still measure the full battery voltage at the starter until you try to crank. Even measuring with an ohmmeter is tough because the resistance is so low. That is why the quickest and most reliable method is to either measure while cranking or to use jumper cables and parallel them across the existing cable. If everything is then fine, you have your answer.
 
Just something I would check if the wires and connections are OK:

Make sure you aren't dropping oil onto the starter from a leak at the OFA or valve cover. Oil soaked starters will fail pretty quickly. I killed one this way in my 96 before replacing the OFA o-rings to stop the leak. I also had a similar problem in an Aerostar.

If your starter is oil soaked you can't usually save it (without a rebuild) but if this is the problem, stopping the leak will keep you from also killing the replacement.
 
I'll put my money on battery or poor connections. I've lost two starters, and both times they would intermittently not crank at all....turn the key a few times, and suddenly they'd crank. Just how mine have failed....
 
Even if it isnt the connectors, which i agree it may be, i usually ALLWAYS replace the ground cable with a larger gauge that i have made from welding cable. You can buy it from farm supply places usually. The factory ground gauge is fine, but after 20 or so years they corrode down into the insulation and when i replace things i usually go a little bigger by default. Also there are usually a lot more items drawing current once i get alold of the Jeep. Like lights, stereo, accessories...
 
Ding, ding, ding....we have a winner.

The battery is the culprit. It fooled me because it would still put out enough juice to turn the motor over, but just barely, which led me to believe it was a starter issue. I had it tested at the Interstate Battery store and it was barely putting out 100 cca's whereas it should have been over 700. The alternator is good and is pushing 14volts once rolling.

This also explains my difficult starting conditions that began to occur about 25% of the time. Actually, the car would start but immediately die. Once I got it started I had to rev the engine to keep it running until rolling - this only happened 1 out of 4 times, so I was starting to lean towards the IAC valve as a probable/possible cause.

Alas...the battery.

thanks fellas.
 
mhopton said:
The battery is a 1.5 year old Interstate
Click to expand...

mhopton said:
Ding, ding, ding....we have a winner.

The battery is the culprit. It fooled me because it would still put out enough juice to turn the motor over, but just barely, which led me to believe it was a starter issue. I had it tested at the Interstate Battery store and it was barely putting out 100 cca's whereas it should have been over 700. The alternator is good and is pushing 14volts once rolling.
Click to expand...

Glad to hear it's up and running again--
do yourself a favor and clean all the connections again. A battery should last more than 1.5yrs if everything else is good. Have the charging system checked again with the clean connections and good battery installed-- 14v is only a good reading if it's DC current and a failed diode in the alternator will allow 14v that will be AC current. One of the quickest ways to kill a battery is to charge it with AC current
 
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