W211 starter motor relay fuse blowing

[njt0001]

Can someone please help. Called out the AA when the car wouldnt turn over and they diagnosed a blown 20 amp starter relay fuse. Once changed the car started but the same fuse has blown twice more since.
Does anyone know if this a common problem and what may be causing it.
Thanks in advance.

 

[Cole@MBS]

Common fault with the 211 and the 203, short on the starter itself, new starter is normal cure!!!

Welcome to the forums...

 

[njt0001]

W211 starter relay fuse keeps blowing

Thanks for the reply.
I guess that will be the solenoid / coil on the starter. Do you know if the starter / solenoid can be sourced seperatly as the starter wont come cheap.
I had believed there was a seperate 'starter relay' so my first thoughts were some sort of problem with tracking to earth on the coil connections of that. From your post I assume that the 20 amp fuse supplies direct to the starter solenoid. (I dont have any circuit diagrams).
Many thanks

 

[mattkh]

From your post I assume that the 20 amp fuse supplies direct to the starter solenoid. (I dont have any circuit diagrams).
Many thanks

Hi
I doubt that the starter solenoid will need 20 amps to operate.

 

[rpe2]

http://forums.mercedesclub.org.uk/showthread.php?t=46827

 

[television]

Hi
I doubt that the starter solenoid will need 20 amps to operate.

The first pull will draw near on that 20 amp and run at 15amp

 

[njt0001]

W211 starter relay fuse keeps blowing

Thanks for the replies.

To date my fuse has blown 3 times from approx. 30 starts. I guess that frequency will increase.

I have been looking at prices for replacement starters and they range from £393 + VAT for a replacement from a merc dealer to £120 for a Lucas service exchange.

Do the Lucas starters have a good name ?

Regards

 

[rpe2]

http://www.eurocarparts.com/ecp/c/M...20cebd6cff3967558480438da28fdef428a2904f&STAM

 

[television]

Nothing wrong with Lucus starters, and the Bosch look good in the above post

 

[Lemere]

Common fault with the 211 and the 203, short on the starter itself, new starter is normal cure!!!

Welcome to the forums...

Interesting Views on the starter fuse. If it were mine: 1st action, connect live feed to terminal 50 and listen to the operation of the starter. Does it sound correct? Yes? then consider this:
The W211 has a 20amp fuse. This fuse feeds the starter mini relay (top of the SAM with the other fuses under the hood) that in turn allows power to the starter solenoid. The starter solenoid has TWO windings, a Pull-in and Hold-in. Pull-in winding is usually rated at circa 30amps, the hold-in at circa 8amps. So, as you operate the starter there is an initial draw of about 38 amps against a 20amp fuse !!! How can that be ??? Well, a fuse melts to fail. The initial Pull-in winding operates only for a part of a second maximum and as the big starter contact in the solenoid is energised, the Pull-in negative becomes a positive, and stops, from then the Hold-in (8amps) remains energised until the starter key is let go.

Earlier W211's had Valeo starters that were not good, they were superseded to Bosch.

If it were mine: Second action: remove the starter, in doing so check well that the connections were good. Starter on the bench: dismantle it and wash clean. Examine the starter gear: If it for some reason it did not engage cleanly with the flywheel ring gear then the Pull-in (30amp + 8amp hold-in) would remain energised too long and the 20 amp fuse would melt. Look at the lever pivot that pushes- in the starter gear, check that it is free and in its correct position. Whilst there, clean the commutator with light emery cloth and then check each segment with your Ohm meter putting the testing prongs opposite and moving around the com. Obviously check the brushes. If you have a megger check the field coils. (Just for good order, - it will have no effect however on the starter fuse blowing) ) . On assemble; smear a little copper slip on the shaft allowing the starter gear some joy on its journey to meet the flywheel ring gear. Lube the pivot also.
You could change the starter fuse from 20 amp to 25amp (but no more!) If the fuse blows again, consider buying a replacement solenoid (readily available for the Bosch) If it is Valeo, I would buy an exchange starter circa £120 .
Finally: Be curious. Or, be like an old pal of mine that always said; "Don't worry, there's nuthin that money won't fix" Requirements: big pile (£) and big shovel

 

[Blobcat]

Interesting Views on the starter fuse. If it were mine: 1st action, connect live feed to terminal 50 and listen to the operation of the starter. Does it sound correct? Yes? then consider this:
The W211 has a 20amp fuse. This fuse feeds the starter mini relay (top of the SAM with the other fuses under the hood) that in turn allows power to the starter solenoid. The starter solenoid has TWO windings, a Pull-in and Hold-in. Pull-in winding is usually rated at circa 30amps, the hold-in at circa 8amps. So, as you operate the starter there is an initial draw of about 38 amps against a 20amp fuse !!! How can that be ??? Well, a fuse melts to fail. The initial Pull-in winding operates only for a part of a second maximum and as the big starter contact in the solenoid is energised, the Pull-in negative becomes a positive, and stops, from then the Hold-in (8amps) remains energised until the starter key is let go.

Earlier W211's had Valeo starters that were not good, they were superseded to Bosch.

If it were mine: Second action: remove the starter, in doing so check well that the connections were good. Starter on the bench: dismantle it and wash clean. Examine the starter gear: If it for some reason it did not engage cleanly with the flywheel ring gear then the Pull-in (30amp + 8amp hold-in) would remain energised too long and the 20 amp fuse would melt. Look at the lever pivot that pushes- in the starter gear, check that it is free and in its correct position. Whilst there, clean the commutator with light emery cloth and then check each segment with your Ohm meter putting the testing prongs opposite and moving around the com. Obviously check the brushes. If you have a megger check the field coils. (Just for good order, - it will have no effect however on the starter fuse blowing) ) . On assemble; smear a little copper slip on the shaft allowing the starter gear some joy on its journey to meet the flywheel ring gear. Lube the pivot also.
You could change the starter fuse from 20 amp to 25amp (but no more!) If the fuse blows again, consider buying a replacement solenoid (readily available for the Bosch) If it is Valeo, I would buy an exchange starter circa £120 .
Finally: Be curious. Or, be like an old pal of mine that always said; "Don't worry, there's nuthin that money won't fix" Requirements: big pile (£) and big shovel

Hello and welcome,

Almost a 10 year old thread...

 

[mattkh]

Earlier W211's had Valeo starters that were not good, they were superseded to Bosch.

In what way were the Valeo starters not good..?

 

[Blobcat]

In what way were the Valeo starters not good..?

Quite a few on the W211's leaked into the ATF coolant pipe within the water radiator - this causes water into the ATF and can ruin the gearbox...

 

[mattkh]

But the thread mentions starter motors..!

 

[Lemere]

Your question: Valeo starter motors not being good. Ask MB they ceased using them on the W211 and, I believe on later models. If you ask MB the dealer to identify a replacement on EPC it will only identify Bosch even when the original was Valeo. They will supply spares for the Bosch, pinion, bearings, solenoid etc. If you remove a Valeo from this period I defy you to find any spares from any source, - unless you are more resourceful than I. Valeo is French (like me) and found on most French cars, but rarely on MB. Like all manufacturers, warranty claims by dealers are so configured that the faults are fired into the design depts. where they attempt to design the faults out. Or, with a problematic supplier they find another. Factors will take a Valeo in part exchange for another make, for your W211 - no problem.