W124 220e Wont Start

[PETE HAYWARD]

Hi, Can Anyone Help. The Car Over The Past Couple Of Months Has Been Playing Up When It Comes To Starting.there Is A Strange Vibrating/buzzing Noise Coming From Behind The Battery Whenever You Turn The Ignition Key And Although The Engine Turns Strongly It Just Wont Start.as I Say It Has Been Doing This On Occasion For The Past Couple Of Months But Now It Happens Constantly.any Advice Would Be Appreciated.

 

[paulcallender]

Hi, Can Anyone Help. The Car Over The Past Couple Of Months Has Been Playing Up When It Comes To Starting.there Is A Strange Vibrating/buzzing Noise Coming From Behind The Battery Whenever You Turn The Ignition Key And Although The Engine Turns Strongly It Just Wont Start.as I Say It Has Been Doing This On Occasion For The Past Couple Of Months But Now It Happens Constantly.any Advice Would Be Appreciated.

Sounds like your fuel pump relay is broken - this is located behind the battery, its a double relay (combines its function with kickdown) at the back.

It would be worth a double check to see if it is the relay - test for +12V at the fuel pump (just in front of right rear wheel) during turning the engine over.

 

[PETE HAYWARD]

Thanks for a quick response Paul. Not that i know much about mechanics or electrics but i can hear the fuel pump kick in when you turn the ignition on..l

 

[paulcallender]

I only guessed at the fuel pump, because thats where its relay is located. Its making a noise, isn't necessarily an indication that its working. You need to find what's clicking, because it definitely doesn't sound right.

Until you identify if its fuel or ignition related, you're just guessing and trying things. So, you're next step would be to check for a spark, using another spark plug on one of the leads. If looks all ok, check for fuel delivery (crack off the fuel line and check fuel flows, when you spin the starter).

 

[paulcallender]

I just realised, your engine might have coil packs and not a conventional coil/distributor. In that case, to identify ignition-related issues, your first port of call would be to read off any diagnostic fault codes. You'll need to find a suitable specialist with the correct reader for your model, eg Carsoft or something like that.

 

[turnipsock]

Does it sound like something is arcing? It might be worth moving the battery and conecting this with jump leads so that you can have a look behind the battery while trying to start the car.

 

[PETE HAYWARD]

Ok Its The Weekend And Ive Had A Chance To Fiddle With Things And Have A Proper Look.....the Item Making A Painful Noise Is The Silver Oblong "relay" That Is Bolted To The Back Of The Engine Compartment Behind The Battery It Has A 4amp Fuse Under A Clear Flip Up Cover And Is Seperate From The Other Two Relays That Are Plugged Into A Kind Of Tray.could It Be This Thats Preventing The Car From Starting?.

 

[paulcallender]

OVP (overvoltage protection) relay.

http://forums.mercedesclub.org.uk/search.php?searchid=82933

 

[PETE HAYWARD]

Paul, Is It Possible To Open The Casing Of The Relay And Have A Look Inside ? It Only Seems To Be Held On By A Couple Of Turned Over Ali Edges? Thanks For Your Help So Far

 

[paulcallender]

Paul, Is It Possible To Open The Casing Of The Relay And Have A Look Inside ? It Only Seems To Be Held On By A Couple Of Turned Over Ali Edges? Thanks For Your Help So Far

Yep, its quite possible. Its very unlikely that it will work once you've 'fiddled' with the internals, though. If you can afford a Mercedes, surely you can afford the replacement relay? Good luck and maybe you can prove me wrong!

 

[PETE HAYWARD]

Thanks Paul,i Might Just Pluck Up The Courage And Have A Look Inside In The Morning. Hopefully It Will Be Evident That Either Its Faulty Or Ok.if Its Faulty I`ll Save Up And Buy A New One.will Post Again To Let You Know Whats Happening.cheers

 

[turnipsock]

It sounds like the contacts are burnt out. You would be better getting a new one. Take the relay apart and clean up the contacts and you will get a bit more out of it.

 

[television]

I just realised, your engine might have coil packs and not a conventional coil/distributor. In that case, to identify ignition-related issues, your first port of call would be to read off any diagnostic fault codes. You'll need to find a suitable specialist with the correct reader for your model, eg Carsoft or something like that.

All of our codes can be read with a simple LED, that consist of the LED,1 resisistor, 1 switch and 3 short lengths of wire, put it in a box or pen and that's it
Malcolm

 

[PETE HAYWARD]

Okay , And I Apologise To Those That Allready Know Everything That I Am About To Write But It May Help Or Just Be Of Interest To Others........i Took Out The " Ovp " Relay And Undone The 2 Small Ali Clips Holding The Electronics In The Casing(took The Fuse Out Of The Top First As This Also Is Attached Through The Casing And Into The Electronics).inside Is Quite A Simple Arrangement Of A Couple Of Relays Which Are Spring Loaded And A Small Electromagnet Plus Some Electronics That Are Way Beyond My Comprehension,anyway It All Looked Ok And The Relays Would Move Under Light Finger Pressure But I Took The Small Springs Off And Very Lightly Oiled Them I Then Used My Compressor To Give The Rest A Good Blow To Dislodge Any Dust/dirt Or Residue That May Have Been There.replaced The Springs Taking Great Care Not To Stretch Them At All.replaced The Ali Casing Cleaned Up The 8 Pins On The Bottom And Also The Receiving Holes In The Plug End Fixed It Back In Position With Its 2 Bolts.turned The Key And ........vroom
Started First Time,i Have Subsequently Started It And Driven It 5 Times And It Seems Perfect.now That I Am 99% Sure That That Was The Problem I Will Buy A New Relay.thanks For Reading This And Thanks To Those That Commented.

 

[paulcallender]

Okay , And I Apologise To Those That Allready Know Everything That I Am About To Write But It May Help Or Just Be Of Interest To Others........i Took Out The " Ovp " Relay And Undone The 2 Small Ali Clips Holding The Electronics In The Casing(took The Fuse Out Of The Top First As This Also Is Attached Through The Casing And Into The Electronics).inside Is Quite A Simple Arrangement Of A Couple Of Relays Which Are Spring Loaded And A Small Electromagnet Plus Some Electronics That Are Way Beyond My Comprehension,anyway It All Looked Ok And The Relays Would Move Under Light Finger Pressure But I Took The Small Springs Off And Very Lightly Oiled Them I Then Used My Compressor To Give The Rest A Good Blow To Dislodge Any Dust/dirt Or Residue That May Have Been There.replaced The Springs Taking Great Care Not To Stretch Them At All.replaced The Ali Casing Cleaned Up The 8 Pins On The Bottom And Also The Receiving Holes In The Plug End Fixed It Back In Position With Its 2 Bolts.turned The Key And ........vroom
Started First Time,i Have Subsequently Started It And Driven It 5 Times And It Seems Perfect.now That I Am 99% Sure That That Was The Problem I Will Buy A New Relay.thanks For Reading This And Thanks To Those That Commented.

Well done for fixing the relay!

I had a similar situation once - on a different car, with a relavitely simple fuel pump relay (tachometric cut off). The relay was faulty, the AA man spent an hour by the roadside taking the cover off and resoldering the internals, etc, put it back on and it caught fire! In the end the car had to be put onto a trailer for the rest of its journey!!!

 

[tom7035]

The only other improvement left Pete is to stop using capital letters on every word in your posts! Makes them difficult to read!
Cheers. Tom.