THIRD (3rd) 300-24 EZL failure in 1 year

[ray_hennig]

Do you not still get Bosch leads for these cars ? Bosch was always my preference , just a personal thing . I know with the dizzy caps I haven't seen Bosch ones for years , and ended up using Beru in preference to Bremi ( which I tried once and had to replace in less than 10,000 miles .

Yes, mine are Beru.

And I've got NGK too.

Don't like either of them.

I had a Bremi rotor arm ages ago and it coughed after a few months off and left me stranded in the local bar tabac. Could be worse!

R

 

[219]

Thanks and noted. There's an update and the following are compatible:

Original: A0105459532 (Bosch 0027400736) or A0105459632 (Siemens: 5WK6 K30571HR1).

Updated: A0125452032 (Bosch 0227400738) or: A0125452132 (Siemens EZ0051 5WK6 K30575HR1).

My burnouts have involved 2 x A0105459532 (the original that came with the car and a 2nd hand buy) and 1 x A0125452132 (a 2nd hand buy).

Installed in the "perfect running" car is a second hand A0105459632.

In stock and tested is a brand new (well, built in 2003 and supplied to me by MB in Bochum earlier this year) A0125452032.

Thanks again.

R

Ray , do you still have all the dead EZLs ?

With nothing to lose , I wonder if it is possible to cut them open with a Dremel and replace individual components inside them ? I know components may be ‘potted’ in some compound , but it might be worth opening up a dead one to see what you find ? Or does anyone offer a repair service on them ?

They may contain commonly available output transistors for example ?

 

[ray_hennig]

Ray , do you still have all the dead EZLs ?

With nothing to lose , I wonder if it is possible to cut them open with a Dremel and replace individual components inside them ? I know components may be ‘potted’ in some compound , but it might be worth opening up a dead one to see what you find ? Or does anyone offer a repair service on them ?

They may contain commonly available output transistors for example ?

I have all 3 dead ones. I tried halfheartedly to split one open but quickly gave up. Life's too short.

I also proposed to a US outfit that they take all 3 and return 1 repaired one - no response.

I've got another used one on order from the US that I'll install to test so that then I'll have a secondhand one and a new one, in the "Survival Kit" in the boot.

And then I'll wait. Will I blow another? And, if so, will it fail for the same reason?

This is all rather confusing given that the 1st one lasted 28 years!!!

RayH

 

[219]

If any consolation , my 300TE-24 got to 430,000 miles without , to my knowledge , blowing one - I got the car at 17 years old and comprehensive service history from the one owner - I don't recall seeing an EZL in the many items that were replaced .

My 300SL-24 also never had issue with the EZL , although the aftermarket ignition coil fitted by a previous owner failed within a week of me getting the car ; I fitted the correct Bosch one , sourced from Carl Burgess of R129.co.uk and the car covered a further 100,000 miles in my hands without further trouble .

I have also had many M103 and M102 cars without any EZL problems .

 

[optimusprime]

Did not have my car long , and i read on the forum about these EZL moduals going down .So right away i purchase one from Ireland at £90 that was back in 2014 .Tried it out to make sure it was a good one .And keept it as a spare . I picked up a few other parts that can be a problem. .
I use new Beru ht leads ,,and plugs ,,all risistor free . But i used new original Bisch distributor cap and rotor . Quality is so good with Beru i would purchase them again if need be . The Beru ht parts were original fitment on Mercedes W124 as well as Bosch . The ht parts that i removed are 31 years old and after i changed them i noticed no change at all in the start and running of the car . Same time i did the HT side i replaced the injectors.. I replaced them with Bosch including new seals and o rings . The car milage is only 90,000 so may be thats why .. Other members might not support this , but a friend who serviced the W124 W123 and the W201 some years baxck said he had never changed a set of injectors in all the time he serviced the Mercedes,, only the seals ,,and o rings .

 

[grober]

They are encapsulated/ surface mount devices with unlabelled components making them irrepairable read the Youtube notes of the person who posted it and he's an electronics guy!

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[optimusprime]

So very interesting . And no one makes them anymore . Just second hand for most W124 on Ebay .

 

[grober]

Anyone opened a failed EZL before?

 

[ray_hennig]

So very interesting . And no one makes them anymore . Just second hand for most W124 on Ebay .

As to whether anyone still makes them, I cannot say.

But they are still available from MB but they appear to be NOS. The "new" one I got in Germany was made in 2003.

Some years back someone said that MB Classic in Stuttgart trawled the world dealerships for these and "repatriated" them.

Price in Germany? 1200€.

Someone on the MB UK Club forum was quoted about £1000 by MB Milton Keynes.

I was quoted 2300€ by MB Angouleme.

And so it goes on ...

RayH

 

[grober]

I believe this is a german company who repairs ?? them

about us - the car-ecu-repair.com team

ecu.eu - first address for car ecu and electronics. We fix car ecu, ABS and other electronics

ecu.eu

 

[ray_hennig]

I believe this is a german company who repairs ?? them

about us - the car-ecu-repair.com team

ecu.eu - first address for car ecu and electronics. We fix car ecu, ABS and other electronics

ecu.eu

Yes, I've seen them. And there is one or more in the US. I'd rather deal with Germany so I'll approach them for comment.

I might as them if they'll do a deal on returning 3 dead ones in exchange for a single repaired one.

R

 

[grober]

under 300x magnification - it aint pretty!

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[wrdcc01]

When you got the recon alternator did you get an auto electrics shop to bench test the old one? If not it is worth it as it could prove a fault capable of causing your issue which is now cleared. Sods law that when you changed the leads the first time, it just happened to coincide with a rectifier diode going duff.

 

[ray_hennig]

When you got the recon alternator did you get an auto electrics shop to bench test the old one? If not it is worth it as it could prove a fault capable of causing your issue which is now cleared. Sods law that when you changed the leads the first time, it just happened to coincide with a rectifier diode going duff.

Thanks for that and, yes, I have considered this. I have retained the old unit but I live way out in the sticks and don't know of a local outfit that could test it.

I'll give it thought though.

R

 

[wrdcc01]

Thanks for that and, yes, I have considered this. I have retained the old unit but I live way out in the sticks and don't know of a local outfit that could test it.

I'll give it thought though.

R

Leave it in the boot and you might find yourself unexpectedly with time to spare and pass by a place when you are out and about.

 

[ray_hennig]

25 August 2020

Not exactly an update but a status report.

After 3 EZL burns we've:

> Checked and cleaned all earth connections.
> Installed a new alternator (90 amp).
> Installed a new starter motor.

Has anything changed? No, the car is running like new but it was before the first EZL failures.

To recap, I said that my impression was that the EZL death was on start up. That was just an impression; there is no evidence of this.

EZL death may be happening on shut down. Does this give us any other clue? Not that I can see.

>>> One small difference is that, if the car is idling and one raises the electric windows, the rev counter doesn't move. Before installing the new parts, the revs would drop noticeably and recover.

Any clue here?

To my mind it must just be the grater capacity of the new alternator.

As always, any and all comments welcomed.

Best to all.

RayH

 

[grober]

Starters and Alternators: Common Misdiagnosis | KnowYourParts
QUOTE:-
Bad diodes are a common cause of alternator failure. The diodes are part of the rectifier assembly that converts the alternator’s AC output to DC. The alternator’s charging output flows through six diodes in the rectifier assembly before it goes to the battery and electrical system. Consequently, the higher the charging load, the hotter they get.
Normal driving and charging loads won’t burn out the diodes, but infrequent driving and short trip nighttime driving with lights and other accessories on can increase charging loads and significantly shorten their life.
The charging output of the alternator drops when diodes fail. If only one or two diodes have failed, the alternator may still produce enough current to meet the vehicle’s electrical needs, but it may not be enough to keep up with higher loads or keep the battery fully charged. This could cause the battery to run down over time.
Diode failures may also allow AC current to leak into the electrical system. AC voltage creates electrical “noise” that can confuse electronic modules and digital communications. A leaky diode also can allow current to drain out of the battery through the alternator when the vehicle is not being driven.

 

[ray_hennig]

Starters and Alternators: Common Misdiagnosis | KnowYourParts
QUOTE:-
Bad diodes are a common cause of alternator failure. The diodes are part of the rectifier assembly that converts the alternator’s AC output to DC. The alternator’s charging output flows through six diodes in the rectifier assembly before it goes to the battery and electrical system. Consequently, the higher the charging load, the hotter they get.
Normal driving and charging loads won’t burn out the diodes, but infrequent driving and short trip nighttime driving with lights and other accessories on can increase charging loads and significantly shorten their life.
The charging output of the alternator drops when diodes fail. If only one or two diodes have failed, the alternator may still produce enough current to meet the vehicle’s electrical needs, but it may not be enough to keep up with higher loads or keep the battery fully charged. This could cause the battery to run down over time.
Diode failures may also allow AC current to leak into the electrical system. AC voltage creates electrical “noise” that can confuse electronic modules and digital communications. A leaky diode also can allow current to drain out of the battery through the alternator when the vehicle is not being driven.

Thanks Grober. Useful input, as always.

And interesting reading.

Diode failures may also allow AC current to leak into the electrical system. AC voltage creates electrical “noise” that can confuse electronic modules and digital communications.

This would be consistent with my failure mode: Perfect performance, Switch off, Crank, No restart, EZL dead.

But I have never had starting problems, even, recently, when the car was left for several weeks.

If the latest EZL does not fail within, say, 18 months, I could start to believe that the problem is solved. But I am unlikely to to know the cause.

Thanks again.

R

 

[ray_hennig]

I didn't update after installing a complete new HT system, from coil to plugs, sourced 100% from MB. Together with a second hand EZL.

All well after 4 years but we don't know definitively what killed the 3 EZLs. I suspect the coil.

Oh well, happy enough aside from being close to 1000€ light!!!

RayH

 

[Ted]

My thoughts would be that maybe you were using a coil for a ballasted system that had been bypassed, or the same coil on a non ballasted system.