I've got a 96 850 with a strange problem. When the weather is warm and I drive at least 15 minutes the car won't start (starter won't even click). I've checked the battery (over 12v) and even replaced it twice, yet the problem persists. What's odd is if I get a jump the car turns over and starts right up. Againk this only happens when the outside temp is warm.

Any help is appreciated!

Thanks,

jeff

 

Sounds like a bad connection somewhere.
Do you have access to a Digital multi meter?

 

I do have access to a multi-meter. I've been tracking the Vdc on the battery (both when it starts and doesn't start) at it almost always around 12.5v. It just seems odd that a jump will always turn the motor. Is it possible the starter is going bad and the extra volts and/or amps from a running vehicle is enough to get it going?

Where should I start with the mulit-meter?

Jeff

 

Yes the starter could be going bad and drawing to many Amps as well as the battery getting weak.
With the car running check voltage at the battery. You should be at about 13.5 or so.
If not then probe the positive cable before the terminal and see what you get there compaired to at the battery. The battery terminals are starting to go bad on these cars. So the battery won't be getting a full charge.

 

Sorry for my late reply but I was away all week. I checked the battery cold and it was around 12.2 v. I started the car and the reading jumped to 13.9. I also checked the input to the starter and it was 13.9.

I'm guessing that either the starter, the battery cables or the connection between the two degrades with the heat and the 12.2 v battery can't overcome the problem.

 

Yep! You're correct - 12.2 volts will not overcome the problem as the battery is basically knackered.

A 12 volt battery should have these readings:

12.7 volts = 100% operational
12.45 volts = 75% operational
12.24 volts = 50% operational
12.06 volts = 25% operational
11.84 volts = 0% operational

The 13.9 volt readingwhen the car was running would be the voltage generated by the alternator.

 

Have you got it fixed yet?

If so, what was the problem?