Slow Cranking

[deboy922]

My 2003 Liberty 200k+ miles with 3.7 V6 is slow cranking over. For the last week or so it seems to be getting slower but is inconsistent.

Yesterday morning, it cranked pretty slow in my 70-degree garage. After work it cranked better but slow, and the temp was 55-degrees outside. I drove for 10 minutes and stopped for gas, and it cranked really slow but started. I drove 20 minutes home; shut off the Jeep; and tried to re-start; and it cranked just a little and would not start. About 5 minutes later, it cranked slowly and started. This morning it cranked a little slow but not bad.

Battery is 2-1/2 years old and shows 12.4 volts when Jeep is not running. Shows 13.8 volts when running at idle, so I think the alternator is OK. Load checked the battery with cheap harbor freight load tester, and it checked OK. There are no other problem and no warning lights. I put a trickle charger (2 amps) on the battery overnight, and it made no difference.

Any advice? I am thinking about installing a new battery because it is easy, and I have had bad batteries do some strange and inconsistent problems (but hate just changing out parts). I think it could be the starter; but I have never experienced a starter slowly dying; and it is difficult to replace. I have done a lot of searching on this forum, but I am not confident in my trouble shooting so far.

Thank you.

 

[LibertyTC]

Find a battery shop with a good commercial load tester, like a Midtronics. Battery may not pass.
Take the battery terminals off & try using a wire brush or emery cloth to clean up the posts & cable ends, then make sure they are on there tight.
It is also a good idea to look at connections at starter motor as well.
If you need a new battery, consider a sealed & more powerful AGM battery. (absorb glass mat) they will last longer than lead acid types.
I use an Odyssey Pc-1500 34-78 DT and it's on year 8 and still reads 880 aprox CCA. I expect to get 11+ years with trickle charging it up a few times per year.

 

[deboy922]

Find a battery shop with a good commercial load tester, like a Midtronics. Battery may not pass.
Take the battery terminals off & try using a wire brush or emery cloth to clean up the posts & cable ends, then make sure they are on there tight.
It is also a good idea to look at connections at starter motor as well.
If you need a new battery, consider a sealed & more powerful AGM battery. (absorb glass mat) they will last longer than lead acid types.
I use an Odyssey Pc-1500 34-78 DT and it's on year 8 and still reads 880 aprox CCA. I expect to get 11+ years with trickle charging it up a few times per year.

Thank you for the input. I have cleaned the battery terminals & cable ends with a wire brush and sand paper, and the connections are tight.. I used sand paper on the ground terminals on the firewall. I traced the engine block ground to behind the oil filter, but can't see it and not sure if you can get to it by removing the oil filter. The starter connection are difficult to see also, but I will look again.

Thanks for the advice on Midtronics load tester...I will look around...and on the Odyssey battery...good stuff.

 

[Billwill]

You can take a thick cable such as a pair of Jumper Leads and temporarily clamp the negative lead of the battery direct onto the starter motor body to check if there is a grounding problem.

The battery voltage should not drop below about 10 volts while cranking...lower than 10 volts means internal resistance in the battery is high or the starter is drawing excess current.

The solenoid could have dirty contacts internally or the starter could be on its way out.

 

[deboy922]

Jeep did more intermittent slow cranking...cranked slow in the morning...good around noon...good after work...drove 15 miles and stopped by parents house, cranked really slow and could not start...jump started and cranked strong...now, is where I thought more it was a bad battery.

Installed new battery, and Jeep is now cranking fine. Time will tell, but I am hoping that I am good to go.

Sorry if I made a mountain out of a mole hill. But the intermittent problem, battery only 2-1/2 years old, and passing the cheapy load test; made me think it was not a bad battery.

Thanks for your guys input. This forum shares a lot of good knowledge, and I am very appreciative.

 

[LibertyTC]

Good to hear that a battery replacement restored the cranking power!
While I am here talking batteries, for a small premium most manufactures now produce the more powerful AGM series of batteries for a reasonable price.
The main advantage to Absorb glass matt's will be overall a higher cranking power, fully sealed they also wont cause corrosion to any terminals.
Napa Legend Premium, Exide Edge, are a good battery for a reasonable price.

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The highest of quality will be the Odyssey, virgin lead, no catastrophic failures ever.
They are top tier with a service life of 12 years.
The volume of plates of the Odyssey is impressive, 15% more than spherical cell type batteries.

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[Jeremy-WI]

One of the maintenance guys from work left early yesterday because his wife could start their Grand Cherokee, he wasn't lucky enough to get away with replacing the battery and changed the starter outside in the wind and the snow.

 

[LibertyTC]

Burr..that does not sound like any fun.

 

[deboy922]

Well, my slow cranking is back. Installed a new battery on 10/31, and Jeep has cranked strong for a month. Drove home Tuesday...Jeep sat for a couple of days...started Friday but cranked slow...same slow crank on Saturday.

I am kind of at a loss...not sure what to check or what to do???

 

[HoosierJeeper]

Sounds like the battery isn't staying charged. Wondering if you have a parasitic draw? Is the alternator OEM?

 

[LibertyTC]

Fun..what is the running/ charging voltage, while using a VOM?
First thing in the AM not running, what is the voltage? Is voltage dropping?
If so, disconnect negative and see if the voltage stabilizes.
I have a load tester to see what the CCA readings are, this is handy, but having a trickle charger on overnight can also bring a weaker battery back.
Cold weather reduces available cranking power quite a bit.
My C-tek charger gets used come winter!

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What brand of battery did you buy? What is the CCA rating/reserve?
You might want to take that battery back for a load test, just to make sure it is still ok.

 

[deboy922]

Thanks guys for the quick replies!

Alternator is the original.

I will research parasitic draw.

Voltage in the morning is 12.4V

Running at idle, voltage is 13.8V

Not sure what you mean by "is the voltage dropping" and "disconnect the negative".

Bought an Autocraft Gold battery at Advance Auto with 800CCA at 0F and 1,000CCA at 32F.

 

[deboy922]

Double checked some voltages before going to work this morning. Jeep had not ran for about 36 hours.

Battery voltage was 12.3V before I started the Jeep. Jeep started but cranked pretty slow in 50-degree F garage. Voltage read 14.3V while Jeep cold-idled at 900 rpm (the running voltage of 13.8V that I reported in the above post was at warm-idle of 600 rpm).

 

[LibertyTC]

All voltages seem reasonable, are the battery terminals clean/free of corrosion & tight? Also check connections at starter motor.
Do you have a trickle charger? If not, drive the jeep for 30 minutes, that should bring the battery's state of charge up.
For peace of mind get the battery load tested to confirm a good battery. Otherwise it may be a starter related issue.

 

[deboy922]

All voltages seem reasonable, are the battery terminals clean/free of corrosion & tight? Also check connections at starter motor.
Do you have a trickle charger? If not, drive the jeep for 30 minutes, that should bring the battery's state of charge up.
For peace of mind get the battery load tested to confirm a good battery. Otherwise it may be a starter related issue.

Thank you for replying. Battery terminals and wire leads have been wire brushed clean and are free of corrosion.

I am going to check for parasitic draw tonight and trickle charge over night. If no joy, I will go to Advance Auto for a battery load test. If battery checks out, I will change the starter. Thanks again.

 

[ltd02]

Resting at 12.3V would be marginal. A good battery should be 12.6 or higher if fully charged. Your alternator reading sounds good so I'd say you are right to get the battery tested. You could run it a bit or charge it fully, then disconnect the cables and check it next day too. If it stays at the same value you had after the disconnect then probably not the battery.

 

[LibertyTC]

Here is an interesting chart. If voltage was 12.3 volts in a garage at 50F, that would actually translate to 90% state of charge.

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Above you can see how colder temperatures effect the voltage/state of charge.
Batteries like warmth! Cold Northern temps will benefit from block heaters & battery warmers!
At 0 F (-17.8c) Available power will only be 40% & power required to crank engine is 210%
This is when greater 800+ CCA rating really matters!

 

[deboy922]

Thank you for replying. Battery terminals and wire leads have been wire brushed clean and are free of corrosion.

I am going to check for parasitic draw tonight and trickle charge over night. If no joy, I will go to Advance Auto for a battery load test. If battery checks out, I will change the starter. Thanks again.

Did not find any parasitic draw...trickle charge did not make a difference...battery passed load test.

Replaced the starter using the below video. To have enough room to slide out the starter, I also had to remove the aluminum structural collar that goes between the transmission and engine oil pan (thanks again to @jeeptorino68 for the tip)...there are (8) 15mm bolts for the collar. I also found an installation procedure for the collar.
- Position collar between transmission & oil pan
- Install collar to transmission bolts - hand start only
- Install collar to oil pan bolts - hand snug only
- Tighten collar to transmission bolts to 40 ft-lbs
- Tighten collar to oil pan bolts to 40 ft-lbs

Also, the (2) 15mm starter mounting bolts are torqued to 40 ft-lbs, and the driveshaft bolts are torqued to 22 ft-lbs.

Jeep is cranking well...time will tell.

Thanks again for everyone's help! I greatly appreciate your willingness to share your knowledge!

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[David Kelm]

Still cranking??