W210 E320 CDi won't start....any ideas?

[robv]

My 2002 E320 CDi with 75000 miles and FMBSH won't start. I've been noticing a few worrying (intermittent) symptoms since Christmas.....

1) When cranking the engine the dash lamps pulse dim with the engine cranking.
2) When cranking the engine the instrument needles flicker downwards or some times drop to zero position, then once engine has started after about 1 second they all flick back up to their correct positions.
3) Occasionally the cranking speed seems slow, then I stop the engine and try it again and it's normal!?!

But despite these symptoms, it has always started first time. Until today.....now I turn the ignition key to the glow plug position, the dash lights all come on OK, then after about a second they all go dim, then when I turn the key to start, all I get is a click from the engine bay and no cranking.

I'm hoping it's just a dead battery - perhaps the voltage drop when cranking is causing the instruments to dip??

My local motor factor said charge the old battery and bring it in for a drop test to see if it's dead, he quoted me £105 for a new Yuasa 100Ah battery.

I would be very grateful for any suggestions? I have the Mobilo life but if they can't fix it, they'll take it to a dealer and I'll need a lottery win to pay for it. I read someone had trouble with an earth strap between the gearbox and chassis, but I couldn't find the strap. I measured the resistance between the battery negative terminal and the Earth post near the battery and it was 0.9 ohm, which seems low, but when cranking at 100 Amps equates to a volt drop of 90V which is a lot, although I have no idea if it goes through something else and it is not a valid measurement to make at that point???

 

[Diesel Benz]

You cannot have 0.9 ohm resistance from the battery negative pole to ground, unless there is a bit issue with the ground wiring (like you calculated, the voltage loss would be absolutely too high).

Did you check your multimeter reading when the probes were directly shortcut?

 

[greyboy]

It's probably the original battery and has now died and gone to heaven. Buy the best you can afford and you will not regret it.

 

[Smiley]

Bosch from Costco - or get a good price from a motor factor

 

[ShinyF1]

Or buy an MB commercial battery I'm told - same as the passenger car, but a fraction of the price....

 

[robv]

You cannot have 0.9 ohm resistance from the battery negative pole to ground, unless there is a bit issue with the ground wiring (like you calculated, the voltage loss would be absolutely too high).

Did you check your multimeter reading when the probes were directly shortcut?

I did - when shorted the reading was 0.1 ohm, the reading I got was 1 ohm. Although when I checked again today the reading was back to 0.1ohm?!? Maybe I just had a bad contact with the probe or maybe there is an iffy connection somewhere else....although when I took the battery out the black lead goes straight to the floor pan and it all looks clean and nice. I was using a Fluke DMM, but I've borrowed a proper resistance tester now so I'll try it again. Thanks for the help though.

 

[robv]

The Saga continues....I took the battery out yesterday and left it charging overnight. I took it today to a local motor factor for a drop test, which he did a few times and it only just dropped below 12 volts - he said the battery was fine (although he did say if a battery has just been charged it can take a lot of tests to get a real reading, but his tester had got red hot!) So I put the battery back in the car and, hey presto, it started first time. I stopped and started it about 10 times - sometimes the instrument needles dipped as before and other times they didn't - so something is still up. Then when I tried it again this evening, it was dead again. So either:
1) there is a current draw on the battery that is flattening it.
2) the battery is dead and was just holding it's charge for a short time.
3) maybe there is a problem with the starter motor or solenoid that is dragging it down???

Anyway I would be very grateful of any more help please. Cheers.

Incidentally, 100Ah batteries: Euro Car Parts Bosch battery £86, Local Motor Factor Yuasa Battery £105, MB Dealer Battery £110. I'll look into the MB commercial battery tomorrow---thanks for that tip!!

 

[Smiley]

If the battery is the original MB one then it is probably at or near the end of its life anyway - just put a new one on. Get a big beefy one - dont skimp on it - you will only regret it one cold morning when you most need the car!

 

[Dieselman]

The needles dropping after starting is a sure sign of low battery power. I suspect your battery is about to meet its maker and is simply losing charge over a period of time.
Try charging it up whilst looking in at the cells. If one is bubbling more than the others it's duff. Then leave the battery disconnected for a couple of days and see whether it has retained the charge.

 

[robv]

If the battery is the original MB one then it is probably at or near the end of its life anyway - just put a new one on. Get a big beefy one - dont skimp on it - you will only regret it one cold morning when you most need the car!

Yes, it's the original MB battery. Car also gets used for a lot of short journeys, so that's probably not helped over the years!! I'm going to try one of the MB commercial ones....thanks for the help!!!

 

[robv]

The needles dropping after starting is a sure sign of low battery power. I suspect your battery is about to meet its maker and is simply losing charge over a period of time.
Try charging it up whilst looking in at the cells. If one is bubbling more than the others it's duff. Then leave the battery disconnected for a couple of days and see whether it has retained the charge.

I'll give that a try in the morning.....many thanks!!

 

[r shelswell]

can you help ! i need to change my noisy diff in my e320 cdi 51 plate with one i have purchased from a scrap car of the same year . is this an easy job ? cheers all new member r shelswell

 

[robv]

can you help ! i need to change my noisy diff in my e320 cdi 51 plate with one i have purchased from a scrap car of the same year . is this an easy job ? cheers all new member r shelswell

Sorry, can't help. Never delved into the diff.

 

[robv]

Update...took the battery back to the local motor factor today to get the drop test done again - this time it showed the battery to be totally dead!! The reason why it looked OK last time was that it had just come off a 24 hour charge - that tricked the drop test. Once that battery had been left for about 5 hours it was dead again and this time the drop test was at -6v and one of the cells was bubbling. So new battery ordered Yuasa Elite 95Ah for £105. I'll put it in tomorrow and let you know if the problems have gone.....fingers crossed!!!

 

[Dieselman]

can you help ! i need to change my noisy diff in my e320 cdi 51 plate with one i have purchased from a scrap car of the same year . is this an easy job ? cheers all new member r shelswell

Yes, but I would advise a trolley jack to lift he diff with, it's heavy. Also make sure it's the corect ratio as an incorrect one won't work. The ratio is stamped on the rear r/h flange next to the backplate.

 

[robv]

New battery in and all problems solved, running like a dream again. Hooray..and...Phew!!