E300 124 Erratic idling

[harpoonlouis]

Just started to notice that my E300 124 is "hunting" slightly at idle, anyone have suggestions as to where to investigate first?

 

[television]

We need to know the VIN fisrt 6 numbers please and the year of the car WDB124???

 

[harpoonlouis]

WDB1241912F******

1994

Perhaps we should all put these in our sig files? ;-)

thanks

 

[television]

Thank you I have the 124191 and that is fine,,you could remove it if you wish the complete VIN if you wish in edit just in case of fraudsters and cloning

 

[Bolide]

If it's a 1912F it's a 300 Diesel

These cars (allegedly) have an ECU to stabilise the idle via control of the fuel rack. I've never found the ECU and think it might be in a relay-type box rather than an ABS-style ECU case

But I don't think that's the problem. I would suspect you have air in the fuel lines and that's making it misfire. Search this forum - there are hundreds of posts on this

If you replace the O-rings on all the connectors in the fuel system you should be able to cure the air leaks. When that's done, report back. there are a few other "usual suspects" but the air leak happens to all 605 and 606-engined cars at some point so you might as well deal with it now

Nick Froome
www.w124.co.uk

 

[harpoonlouis]

Anyone know the dimensions of the "O" rings in the Merc diesel system?

This problem went away but has now returned with a vengence so I need to swap out all the o rings.

 

[Bolide]

There are two sizes. I buy them from the dealer and just ask for a handful. 80p each

Nick Froome
www.w124.co.uk

 

[harpoonlouis]

Hi Nick

Thanks for chiming in again of this one.

What is the minimum required to get the job done?

It's a long'ish round trip to my local MB blood letting agency!

half a dozen of each size?

 

[Bolide]

I think there are two of one size and about eight of another. The parts department should know. If they don't, try Rivervale in Brighton

Ah, yes, there are a couple of O-rings on the fuel shutoff valve (on the filter) as well

Nick Froome
www.w124.co.uk

 

[harpoonlouis]

Thanks Nick

I changed the filter and o rings the other day ( and the shutoff screw still leaks!)

I will grab a hand full and get down and dirty tomorrow


John

 

[Bolide]

changed the filter and o rings the other day ( and the shutoff screw still leaks!)

Replace the screw. About £30

Nick Froome
www.w124.co.uk

 

[Number_Cruncher]

>>These cars (allegedly) have an ECU to stabilise the idle

It's the same one that controls the EGR and the intake manifold resonance flaps.