Alternator / Battery / Idle

[Norris]

Can anyone tell me how you know if its your alternator or your battery failing?

And will a weak battery cause your car to idle really rough?

(Im in the wars with this ****** car)

 

[television]

No sir the battery will not cause poor idle, and it will not be the alternator either as if faulty the warning battery sign would be lit

 

[Norris]

Thank you my friend, looks like it a new battery then

 

[television]

What is the problem with the battery

 

[Norris]

som times it starts some times ot dont, if it was another car i would assume its the battery, with this one (merc) i have to question it.

Turn the ignition lights go dim, doesnt even turn over

 

[mattkh]

Hi
What car is it ?
How old is the starter motor ?
Try to distinguish between cranking and firing.
The ignition switch has an ignition on position and the next one is the starting position. When you say the lights go dim, is this when the key is on the starting position ?

 

[FIBAMAN]

If you are trying to start the car with all the lights on then your battery is sure gonna bend at the knees

 

[panason1c]

If you are trying to start the car with all the lights on then your battery is sure gonna bend at the knees

A 'good' battery should easily start the car even with all the lights on......

 

[panason1c]

Can anyone tell me how you know if its your alternator or your battery failing?

One basic 'no-tools' way is to put your headlights on full beam whilst the engine is at idle, then rev the engine and see if the lights go slightly brighter..........if they do then it's confirmed that the alternator is doing its job and, in your case, the battery is then likely to be suspect. Best to do this test when it's dark for more obvious results.

 

[Pookis Dad]

Rough Idle

I recently changed the plugs and leads in my car ("C" 200 1997 model year) as it was missing slightly. The idle wasn't rough, but it wsn't nice. When accelerating the car seemed to hesitate for a second and now & then would backfire inside the exhaust.

I contacted these guys http://www.gsfcarparts.com/, ordered the parts and had them next day.

Fantastic!

Car goes sweet now.

I am not saying your plugs and leads are duff, but it is possible.....

 

[Cnics]

If the dash lights go dim when you turn the starter, but the starter doesn't always turn there's a good chance its starter related.

Rob

 

[television]

If you are trying to start the car with all the lights on then your battery is sure gonna bend at the knees

Not always the case as all Volvo's have to start with the running lights on

 

[Norris]

When i turn it to start (last position) the lights go dim on the dash, and it doesnt turn,in theory Sounds like the starter. But it doesnt happen all the time. And I can jump start it with a booster / leads.

How hard is it to change the starter motor yourself?

 

[television]

When i turn it to start (last position) the lights go dim on the dash, and it doesnt turn,in theory Sounds like the starter. But it doesnt happen all the time. And I can jump start it with a booster / leads.

How hard is it to change the starter motor yourself?

Only from under the car, its held on with two bolts, not difficult

 

[Cnics]

The starter could stick, causing it to work sometimes and not on others. A failing battery could mean that it doesn't have enough to turn a stuck starter which explains why putting a booster on will help it. Does is work EVERY time you put the booster on?

I'd expect that a failing starter would cause excessive stress on the battery and wouldn't do it much good. It's working out whether that is the cause.

 

[Norris]

ive borrowed another battery, i know is good and it happened again so im thinking it must be the starter jamming

 

[television]

The starter could stick, causing it to work sometimes and not on others. A failing battery could mean that it doesn't have enough to turn a stuck starter which explains why putting a booster on will help it. Does is work EVERY time you put the booster on?

I'd expect that a failing starter would cause excessive stress on the battery and wouldn't do it much good. It's working out whether that is the cause.

This is the bit that worries me

 

[Norris]

Sorry mate can you explain what you mean. This is the bit that worries me

 

[television]

Sorry mate can you explain what you mean. This is the bit that worries me

If it starts with a jump,I would not want you to replace the starter for nothing.

But sitting here now typing I am thinking again, if the car has been slow cranking the car then the stater could be drawing to high current,just through age or use, and 2 batteries over come this.

As long as the wires from the battery are good, including the ground lead and the spades on the ends then it will be the starter.

 

[Norris]

thanks, im going to try changing the starter, i know its not the battery