Did I miss these battery-death hints? Battery spec for 300/24, please.

[isobars]

Hi All,

Up until this morning my 300/24 started in a milli-turn.

Today, after a severe frost, I had to turn the key twice for the first time. After thirty miles, some with the heated seats bringing my buttocks up to temp I turned the car off and successfully restarted, but then, following a short run, on trying to restart three hours later there was absolutely no interest in starting. Though the engine turned over at what I would have called quickly, it started to run down after around a minute’s worth of ten second or so turns.

Yesterday the wipers started to wipe at half speed, when I asked the rear windows to drop the dash light dimmed and the seat belt butler is stuck on extend.

My Battery is ‘gered, isnt’t it?

The car is locked in a car park and I might need to arrive with a battery to convince the zealous guardians that there really is a problem.

The hand book is in the car, so could anyone let me have the spec for a replacement battery for a 300/24 1990, please?

Cheers,

Paul

 

[npuk]

Try Battery Search - Find the right battery-VARTA Automotive or http://www.eurocarparts.com/ will give you the spec

 

[219]

I wouldn't rush into changing the battery until you have confirmed the charging system is working correctly - the symptoms you describe sound more like a battery that was running down slowly as a result of not being charged .

What you need to do is take along a voltmeter and check the battery voltage before any attempt to start - it should normally read 12V but may be less due to being discharged .

If you can get a jump start ( assuming the car will not start by itself - batteries can 'recover' to an extent if left for a while after a failed starting attempt ) then check voltage again once other vehicle has been disconnected - voltage should be more like 13.5 - 14 V if charging system is working correctly ; if it is still down at 11 or 12V then your alternator is most likely at fault .

If you just put a new battery in without checking the above , chances are it will run down in a couple of days too and then you'll be back to square one .

If the battery did turn out to be defective , my 300TE had a 63 amp-hour battery , from memory VARTA model 56318 . The 24valve version will be fine with the same battery ( I have had both ) .

 

[isobars]

Thanks to you both.

Paul

 

[Ade B]

Check the boot light is switching off. Caused problems with mine.

Ade

 

[Ted]

What Pontoneer said.

Sounds more like a charging issue than a battery issue.

 

[Gawdi]

Check the boot light is switching off. Caused problems with mine.

Ade

And mine!!!!

 

[tromppost]

If you do need a new battery try Mercedes. They quoted me £75 and the Bosch one from Costco is £110. I did have to call two Mercedes parts dept, the first Mercedes Ascot was £125 the Hughes of beaconsfield at £75.

 

[isobars]

I picked the car up in January from a dealer where it had stood for nine months, having only done a few thousand miles in the year prior. It was on fast charge from flat for a few hours, cranked first time and has run in mostly darkness ever since – around 40 starts. From this I’d guess that it has been charging OK, but I do suspect a tired battery and perhaps yesterday morning’s combination of demand – fifteen minutes full blower, hot seat, HRW, headlights – was just too much.

Off to check it now.

Thanks for all the advice.

Paul

 

[isobars]

Just called Merc with the Chassis number, and their machine ofered either the 62Ah or 100ah. Unusual?
Should I suppose that colder climes or cars more 'extra'd-up' would take the 100?

62 = £73 100 = £130

Who makes them, I wonder?

Paul

 

[Aletank]

I recently replaced my 11 year old original Mercedes/Varta 100 A/H Battery, my findings where -

Mercedes - £130
Mercedes Commercial - £100
Halfords Bosch £125 or £100 with my Trade Card
Costco Bosch £93
Battery Specialist's Varta £91 - 4 year warranty VARTA H3 (019/017) 100AH 4 YEAR G/TEE CAR BATTERY on eBay (end time 11-Mar-10 10:58:03 GMT) I collected myself as they only 3 miles away from me.

 

[grober]

Personally would go for a 74 amp hour job as a good compromise. [100amp hour if it was a diesel] e.g. VARTA 574 012 068 3132 BLUE dynamic 74Ah 680 cold cranking current

 

[dinoy]

euro part own brand made by bosch with 3 year guarantee and priced around £70 give the registration they tell u which one u do not need 100 one

 

[isobars]

Time made me buy the 100 at 99 (vat back).
If it's a problem I'll pop it into a diesel 300.

Of course, the consensus is that it isn't a battery problem, but it'll get me moving to get it inspected, and the diesels are old ones.
Thanks again.

Cheers,

Paul

 

[isobars]

For Info.

The 100 amp does not fit the battery tray on a '90 coupe!

I wired up a powerful jump-start, but zero, despite the motor spinning so fast I thought it would take off. I must admit, I didn't think the battery was low when it wouldn't start the first time.

The car isn't interested in moving.

There isn't even the faintest smell of petrol.

Time to search for a non-starter thread!


Cheers,

Paul

 

[grober]

Right next check fuel pump relay and/or OVP relay (or its fuse)-ovp supplies the engine ECU among other things Jump starting/disconnecting/connecting the battery can finish of a vulnerable relay or fuse

 

[219]

Can you hear the fuel pump running for a second when you turn on the ignition ?

FPR is the one usually with 'kickdown' printed on top . If you hear pump running on turning key , less likely to be this .

The other issue with M103 and M104 300 engines is the distributor cap , mounted on the front end of the cambox . These have a notoriously short lifespan 20-30k miles and can often be the cause of a non start . You may be lucky and find it is just condensation inside the cap - you'll need an Allen key to remove the three socket head bolts holding it on - bottom one is awkward to get to - a visual inspection should tell you what you need to know . These cars can also be sensitive to condition of spark plugs , but this is more usually a hot running issue than non starting .

The other problem I have seen on these engines is a rubber hose which can pop off the underside of the inlet manifold , killing all vacuum and stopping induction completely .

 

[219]

Further to Graeme's post above , one of the first things I do when I buy any car is to just replace ALL the fuses with new ones . The Continental ( or 'torpedo' type fuses ) used by Mercedes are well known for burning away at the ends where they contact the terminals of the fusebox and can sometimes be duff even though they have not 'blown' .

If either of the relays as above , they can be opened up and usually dry joints on the circuit boards can be resoldered to effect a repair rather than expensive replacement .

At the end of the day , you've only had this car a month or so - any sort of warranty from the dealer who sold you it ? Maybe you can get him to replace any defective parts ?

 

[isobars]

Hi All,

All the fuses are very badly oxydised.

The problem came before I attempted any jumping or disconnection – if it wasn’t due to a low battery, but it did whip the motor round without a hint of starting pre-flattening.

I can’t hear the FP kicking in, but I hadn’t heard it before – I’ll put my head in the boot to be sure.

If it was the dizzy would it have had a try, or would I have noticed fuel?

Recent spark plugs, and a super-smooth t/over.

Are the relays an easy find, and is the first job just checking the contact – sorry to be thick!

I’m beginning to miss the 123D!

Thanks Again.

Cheers,

Paul

 

[219]

The fuel pump should be easily heard from the drivers seat when you just turn on the ignition ( but don't try to start the engine ) : it will be an easily heard whirring sound ( I should have said it will whirr for a second or so just as you turn on the ignition , then stop as soon as the system is pressurised ) ; some of these cars have two pumps , others just have the one - the pump set is located just ahead of the right rear wheel , more or less under the back seat ( accessible from under the car , by removing a plastic undertray ) along with the fuel filter and accumulator , when two pumps are fitted usually the second pump is located directly below the tank , close by the diff . Sometimes the conections to the electric pumps can corrode and stop them working , but the fuel pump relay is the most likely culprit . Relay locations vary - on the W124 , try looking behind the battery , or near the fusebox - usually they will be somewhere along the bulkhead - very occasionally on some models you will find relays in strange places like the passenger footwell !

Here is a picture of a fuel pump set

and a close up of a pump

The fuel pump relay is about the size of a twenty pack of cigarettes and usaully has the work 'kickdown' printed on top . You can prise off the plastic cover and inspect the circuit board inside - the most common problem is solder joints which have deteriorated over the years and can be easily fixed by resoldering - given that most of the relays start at prices of £50 and upwards ( some a LOT more ) it is well worth trying a diy fix . The OVP relay is a tall , thin one with a fuse on top - a fault in this one , though , will tend to cause idling and other problems rather than non start , so I'd start with the FPR first - if the pumps don't run when you turn the key , try locating this relay and just give it a knock - if the pumps then run ( even intermittently ) you know you've found the problem . You 'can' bypass the relay by shorting out two pins ( 7 & 8 IIRC ) but then the pumps will run constantly - OK in an emergency if you are stranded somewhere but not really a good idea .

Here's the FPR on my W126 500SEL

And on this picture of my 190 2.6 , the FPR is just to the left of the yellow circle ( the circle was to show the location of the OVP )

Both the pumps not running and problems with the dizzy would cause the engine not to start even though the starter could spin it over easily ( I wouldn't have expected a duff battery to give you a minute's worth of cranking time BTW ) .

I'd check out the FPR first as this seems now the most likely suspect .

failing that , worth checking for condensation inside the cap , esp since you said car has stood for 9 months and given current weather conditions , it could have just built up to a critical level and shorted out any spark - carbon brush in centre of cap could also have broken ( I have had this before and it can 'just happen' ) .