2002 4.7 litre won't start when cold outside
 

My Grand Cherokee has a new battery, but won't start, won't even crank when it gets below freezing outside.
I had this problem two years ago, put a new starter and battery into it then and problem was fixed. Now, exactly two years later, battery checks out perfect and starts fine in the morning in my garage (+10 degrees) but by mid day, when it is -10 degrees, only makes a click, no cranking. Try over and over again and eventually it will go. Last week, when even that did not work, pushed into the warehouse at work, let it sit an hour to warm up and it started instantly.
Seems like the starter itself is fine, but something within the circuit literally freezes up. A month ago, we had 2 weeks of very cold weather (less than -20) and it worked just fine. And now -5 and it is a no go.
I don't want to buy a new starter, again, when it works most of the time. Thanks.

Re: 2002 4.7 litre won't start when cold outside
 

Id take it to a shop and put it on a battery tester and find out how many cranking amps are available... that starter pulls a ton of amps, and if your battery is cold and cant keep it together... ask them to check the fluid in the battery aswell...

Re: 2002 4.7 litre won't start when cold outside
 

The battery checks out perfect, cranks nearly 1000 amps. I think the problem is either the relay or the solenoid, which is integral with the starter, therefore can only be serviced by replacing or repairing the starter. I am going to a contact starter re-builder to see if there is a history of premature solenoid failure with the 4.7 liter engine.

Re: 2002 4.7 litre won't start when cold outside
 

Did they check the cold cranking amps? Some batteries will test fine but if they look at the cold cranking amp it will show a number between 3 and 9. The most common sign of low cold cranking amps is that it will start when it's warm out but not when it's cold. Walmart will do this for free but you need to make sure they read the cold cranking amps.

Cold cranking amps are stated on the side on the battery usually 500-800.

Re: 2002 4.7 litre won't start when cold outside
 

It's very common for rust to grow between the magnets and outer casing. This eventually causes the armature to be clamped by the magnets, something like a brake, and this extra drag causes it to try and pull astronomical amounts of juice. Four starters in five years on my sons xj for the same reason. Take the starter to a rebuilder, that way you will find out what's wrong with it, if anything, and will cost you about a third the cost of a new one.