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W124 200TE
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Discussion Starter · #1 ·
Hi,

Just thought I'd post a quick comment about what seems to be the 124's major weak spot.

Spent a while last night on this forum because the central locking was very sluggish / inoperable - sometimes worked if the engine was running, but at other times not.

Before attempting / looking for vacuum faults this morning I thought it sensible to check the fuse board. At first glance, everything OK. that is UNTIL you actually take the fuse out ('bullet type'), and inspect the end-caps........corroded as hell where they contact the holder clip.

Put in a new fuse - everything works fine again.

This must be the 8th or 9th time I've had 'odd' electrical problems with the car where corroded fuses have been the cause.....AND as a point of principle I change ALL the fuses for new ones every two years because of it.

I think(?) the problem emanates from using the alloy type fuses against the copper contacts...(electrochemical reaction?), so maybe the answer is to try and find a better quality fuse.

So the moral of the story?........don't just inspect the under-hood fuse board for blown fuses - take them out and inspect the ends for corrosion - replacing the whole lot every year would be minimal cost and might help stop a whole host of silly electrical 'glitches'.

Apart from this 'Achille's Heel' I think the W124 series was a landmark in build quality which sadly seems to have passed us by.

Hope this helps someone else,

Regards,

Spiro'
 

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2001 E320; 2002 ML500
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1,982 Posts
I do agree fuses need to be replaced but the general concensus is every 10 years. My car is 11 years old and I replaced most of the fuses a few months ago. Did not replace the blower motor fuse and it cracked in 1/2 last week.
Do you live in a harsh environment? (close to the ocean?)

Sergio
'95 E320 166K miles
 

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Old problem. But good you bring it up again.
Some people have been successfull using a little dielectric grease on the ends.

I bought brass/copper alloy fuses which don't corrode. You can find them in some autoparts stores. I ordered mine from http://www.mercedessource.com online catalog. I put them in after cleaning each of the contact areas. No problems since.
 

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W124 200TE
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Discussion Starter · #4 ·
I bought brass/copper alloy fuses which don't corrode......

An interesting point....I rang my local MB dealer asking for exactly this and they didn't seem to understand / know what point I was making. Seems that their 'stock' is the alloy type as well.

I suspect that the fuses fitted at manufacture were of a much better quality than the after-market parts - which is why the later replacements aren't lasting that long.

Can't find any copper or brass fuses locally so I'll try the link you posted.

Thanks,

Spiro'
 

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95 E320 Cabriolet, 140K
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1,332 Posts
I reverse-engineered the fuse metal of the original fuses in my lab. They are made of aluminum with tin plating on the surface. This plating gives it a dull appearance. Tin is a very popular material for electrical contacts.

This is where I get confused. I don't experience any corrosion on my fuses. This may be because it's my summer-only car. Are you perhaps mistakening the dull (matte) appearance for corrosion? Tin plating is naturally dull the way it's deposited on these fuses.

I also looked at the replacement fuses. Some were brass (60% Copper, 40% Zinc), the others were 100% Copper. I'm working from memory, but I think the 30A fuses were the pure copper ones.

Copper and brass DO corrode. Nearly every car in the rust belt has electrical problems eventually due to corroded contact at the connectors. These contacts are invariably made from copper, brass, or tin plated brass.
 

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W124 200TE
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Discussion Starter · #6 ·
Hi........

No, not concerned about the dull 'finish'......its the fact that very often the cause of an electrical 'glitch' on the car is due to the end cap of the fuse being completely rotted away where its in contact with the holder.

This often / usually takes the form of a complete ring of metal 'disappearing' from the end cap (which isn't obvious from a quick visual inspection), which effectively / eventually takes the fuse 'out of circuit'.

I've had fuses go from new to rotted in 18 months or less.

As you probably noticed, I live in the UK, (can be damp at times!), but nowhere near the coast.......so its not the sea air.

I note from the link kindly posted above that this is seen by some 'shops' as a persitant problem to only be resolved by fitting a set of higher quality fuses.

I think however that I've tracked down a source of gold-plated fuses - from a marine supplier of all things - but I suppose that makes sense.
Only problem is the cost.....about a dollar-fifty each........but maybe thats a small price to pay to get rid of the problem?

Regards,

Spiro'
 

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I am not saying that brass/copper does not corrode. Thats not the problem. The problem is the fuses and the contacts are two different metals that react to each other when moisture is involved. When you go to the brass/copper fuses they react much much less.
 

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95 E320 Cabriolet, 140K
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You're probably right. BTW, I checked the galvanic series and find that tin is anodic to copper/brass. Should the two touch in a corrosive (wet) environment, the tin would start corroding.
 

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W124 200TE
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Discussion Starter · #9 ·
Hi again........(ongoing story...),

Checked with Marine supplier, turns out that their Continental style fuses are not gold plated but in fact 'standard' like everywhere else. They say that customers who have boats that utilise them report significant fuse corrosion, ( not surprising really !).

I'm amazed given the widespread 'problem' these style of fuses represent that someone hasn't come up with a better quality replacement (e.g gold plated end-caps).

Maybe I ought to buy a load and have them gold plated !!?

I also note that the fuse body on the replacements is for the most part nowadays made from thermoplastic rather than ceramic - which means that if they get hot for any reason the plastic softens and the fuse loosens / falls out !

I wonder how difficult it would be to change / adapt the fuse board to a later style 'Blade' type box (e.g. as in a mid-90's 'C' class) ???

Anyone attempted it?

Regards,

Spiro'
 

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88 Benz 260E
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534 Posts
I wouldn't quite state the electrics at the W124 Achilles Hell. Changing fuses should be done routinely anyways. I can maybe understand the wiring harness issues in the newer W124 as being a major achilles heel of the W124. Now BMW's with their constant electrical gremlins now that's a whole different story

~cali
 

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Its a pain in the butt. Thats why when I have an electrical problem I still check them regardless. Best bet is just to change and clean the contacts every few years.
 
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