alternator??

[martthefart]

Hi, been following the site for sometime - you have to with cars like these just so I don't have an heart attack when they break! They are fantastic cars though. I drive a 1992 E Class 124 with a 3l diesel 603 engine. My problem bagan the other week. My seatbelt/boot light warning light kept coming on the week. THis could usually be fixed by slamming the boot. One of the boot arm things broke sometime ago and haven'y got around to fixing yet. Tuesday just gone, car refused to start. Breakdown came out and jump started car. Battery didn't have enough charge apparently though he said alternator was putting just under 14v back into battery. He suggested battery was knacked. On driving home, indicators stopped working, elec windows slowed and ABS light came on and stayed on. Low and behold, car failed to start next morning so new battery fitted and car run no problem. Friday, same problem car struggled to start and ran, but no indicators, radio, windows ABS light on etc. Drove to gararge who diagnosed a knacked alternator. New alternator fiited that morning, same problem though. Old alternator tested and found to be OK. For some reason the alt doen't put the correct charge back into battery. Got car booked into independent auto electrician for Tues. Popped in main dealer, they suggest a battery drain likely cause and will charge £55.0 to test and then further charge for isolating and fixing problem. My questions to the class is this:
1/ Any ideas of the likely problem?
2/ Having checked forums, it is suggested main dealer should be able to tell which component is faulty by amount of power drained, having identified circuit at fault. Is this correct and so should i take it to main dealer or stick with cheaper independent.

Your swift wisdom is greatly appreciated.

 

[opps-man]

Hi Mart.
You mention a problem with the boot closed warning light.
It may suggest thet the boot light is staying on , this would drain the battery over night.
One way to test is to get in the boot and close it to see if the light goes out(make sure you have someone that you can trust to open the boot for you to get out)
A simpler test is to remove the boot light bulb and see if the car starts in the morning.
Cheers
Don.

 

[Blobcat]

Bit of an aside, you may find that the boot light switch has the option to switch the light off with the boot open. All you have to do is pull the switch out with the boot lid open, once you close the boot again it reverts to being on when the boot is open. The option is to stop the light(s) draining the battery if you are loading/unloading for an extended period. Little things like this I love about my car

 

[martthefart]

Hi, thanks for the reply. I will check the boot light again, but did check the switch before and pressing it in did switch the light off. However, I would have thought this couldn't draw that much power from the battery to flatten it so quickly.

I was wondering about the OVP. One thing I did notice is when the battery died, on turning the ignition key I could the glow plug unit clicking repeatedly. I wonder if this could be the fault.

Any other ideas.

 

[C220GJS]

I was wondering about the OVP. One thing I did notice is when the battery died, on turning the ignition key I could the glow plug unit clicking repeatedly. I wonder if this could be the fault.

Any other ideas.

If your battery was flat at the time, the glow plug unit would be clicking as there was not enough current to hold the relay shut.

 

[martthefart]

That explains that then. Thanks for the reply. Unfortunatley, i am still no closer to identifying the fault. It goes into an auto electrician tomorrow, so will feedback to all.

Thanks folks.
Mart

 

[television]

The OVR can cause your running problems but not the charging or battery going flat. 14 volts is correct for running. When looking for the fault, it is important that the ammeter is joined up before the battery lead removed otherwise the source of the leak could be lost.

Malcolm

 

[martthefart]

problem disappeared??

Hi, took the car into an auto electrician that came highly recommended form my techs. They tested the battery and it was fine. Alternator charging battery up and couldn't find any drain on the system. Car seems to be running fine as well. They suggested the new battery I fitted may have been partially discharged and i had failed to give it sufficient time to recharge?? Otherwise, it may be an intermittent fault. They have been very good about it and agreed to retest for free should problem come back. Can't say fairer than that can you. So fingers crossed for now..:-D

 

[television]

Hi, took the car into an auto electrician that came highly recommended form my techs. They tested the battery and it was fine. Alternator charging battery up and couldn't find any drain on the system. Car seems to be running fine as well. They suggested the new battery I fitted may have been partially discharged and i had failed to give it sufficient time to recharge?? Otherwise, it may be an intermittent fault. They have been very good about it and agreed to retest for free should problem come back. Can't say fairer than that can you. So fingers crossed for now..:-D

If I can add one thing, alternators are not designed for charging flat or very low batteries, since the max voltage that can be applied is only 13.8 volts.
A partly charge battery will soon discharge.

malcolm

 

[martthefart]

The alternator being unable to charge a flat battery could explain the problem with the "new" battery. It appears to be running fine now so fingers crossed.

Thanks for that Malcolm, much appreciated.

Mart

 

[benzburner]

hello again. i think i may be suffering the exact same problem.
are you saying that if i partly flatten my battery by leaving lights on accidentally, it won't charge correctly?