1999 Discovery II

When the weather is cold... 40 degrees or below my disco gets hard to turn over. It barely can turn over... I put a new battery in it last year and that didn't seem to help. I spent good money and put a better/bigger battery in yesterday, and it still hardly turns over. During the summer is turns over just fine.

Any ideas?

 

Yeah, loose/corroded connections between the starter and battery.
Corroded cables.
Bad starter.
Loose/corroded connections between the alternator and battery.
Bad alternator.
Or some combination of the above.
I'd do some diagnostics before spending more money are parts.

 

Thanks. Would loose connections cause hard start in winter, but not summer?

 

Yes, because the chemicals that corrode the connections change with temperature. Her's some ideas of how to check on this with a digital volt meter (can be a $15 one from Harbor Freight).

1. Meter between center of battery studs. Write it down.

2. Turn on lights. write it down, should not be more than 1/2 a volt change. A dead cell in the battery will drop much further.

3. Measure between center of stud and outside edge of battery connector with lights on (which puts a load on the system). Should be so small that it can barely show up, like less than 0.1 volts. A corroded connector will have voltage drop across it.

4. Most likely you have more than one corroded connector. Take battery cables off, an scrub with metal brush until kissable. Same for big wires in underhood fuse box (at the front). Crawl under truck and locate large cables near starter, also clean those and re-attach. There is also a ground bond to the frame by the (-) battery terminal, locate and clean that.

5. Fuse link 13 in the underhood box runs the starter, remove and clean the mounting holes on that.

6. Attached pix of fuse box wiring and terminals.

7. If all this good, could also have bad starter or starter soleniod, can have rebuilt by local starter / alternator shop. PITA to swap out.

 

Yes. In the winter the cold battery doesn't have as much power plus the engine is colder and so harder to crank.

 

Yep, need good batteries. 100% capacity at 80 degrees F. At 32 F, down to about 77% capacity. At -4 F, 55% capacity. So if you start with a marginal battery, when cold it won't have the power to crank the truck. Oil weight also plays a part, 20W50 should be used above 32F as an example.

 

Michael, so people know what you did regarding battery replacement tell us what battery and the CCA ratings were.
Should try and stay with a battery rated at 800 CCA and above, what is yours?

 

And of course, after all these connections to reduce voltage drop are cleaned up, and a good battery, you could still have a starter / solenoid that is beginning to go bad. I replaced my starter and was surprised at how much faster it spins the engine (salvage yard special, and they are just as hard to get off as the one in your driveway, next time I'll buy one instead of doing double work).

 

If it's slow cranking it won't be the solenoid.