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I had a fuse break (not burn out) in my 300E a few days ago. Some of the other fuses are looking suspect too, so I'm going to proactively replace them.<br>
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I ran across this copper fuse kit upgrade that seemed to make sense... you're not supposed to mix aluminum and copper in house wiring so it doesn't seem to make sense in a car either...<br>
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Link here: <a href=http://www.mercedessource.com/parts/lightingparts.html>FUSE BOX REPAIR UPGRADE</a><br>
(It's the third part in the list)<br>
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Any opinions on this kit or the seller? Anyone tried it?
 

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He has been on E-bay with this kit quite often. You are using copper fuses and copper wiring so no problem with that. The idea would be to replace all the fuses with the new type. The problem with the old ones as you have noticed is that they rapidly oxidize and that makes for a bad current transfer. Even when you replace all your fuses with the old type, chances are things will begin to work that you thought were shot! i.e. window motors.
 

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I wonder why MB used aluminum fuses with copper holders... seems like a pretty obviously bad idea.<br> <br> Anyway, I've got a set of the copper fuses on the way. The seller seems like a good guy so far, he put together a custom set for me with a few extras I needed for my car.
 

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They are no really aluminum although they look like it. They are another type of alloy in the same family. Good question. Let us know how the new ones work for you.
 

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The original equipment fuses are not really aluminum, and anyway, the reason for not mixing the two metals in electrical circuts has more to do with the fire danger inherent in their different thermal/conductive properties under load at 110/220 VAC, and would not be a problem at 12VDC! The key to ANY electrical system however, remains: KEEP IT CLEAN! I once was given a car by my sister(a 1973 dodge) which displayed every electrical problem known to man, and for which an otherwise honest mechanic (most mechanics know less about electricity than a cow knows about cube root!) had recommended the replacement of virtually every electrical component on the car-- at a cost which would have exceeded its original purchase price! I spent a relaxing week taking every single electrical component apart (yes, they DO come apart, even such 'sealed' units as headlight switches), and cleaning every single contact. I replaced NOTHING, but when I got it all back together, EVERYTHING WORKED!<br> A trick I used to keep that car working may help you: put a little dab of good, old, cheap, plain vaseline on the contacts; it inhibits corrosion and will not interfere with electrical current flow (at 12volts DC, at least-- don't try this trick with house current!).
 

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Discussion Starter #6
Thanks for the info, so... what are the OE fuses made of?<br>
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Also, the fuse I had flake out on me appeared to have physically broken rather than burning. You couldn't visually see it until removing it, then the two pieces just fell apart.<br>
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In any case, just got my bag of shiny new copper alloy fuses today, guess they can't hurt, and they're pretty. :)<br>
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I did notice some light corrosion at the contacts of others. I figured I'd disconnect the battery to avoid fireworks and go at them with a brass wire brush. Or is there a better trick?
 

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Discussion Starter #7
The fuses are probably made of a variant of woods metal - a lead/tin/bismuth alloy. You vary the proportions to get the melting temp you prefer, as low as 92 C for a eutectic mixture. The advantage is that the fuse will blow at a low enough temp that it won't melt the plastic holder, or start a fire. Also, the lead alloys used in fuses have very low heat of fusion - they'd almost not burn your hand if the fuse dropped the molten metal on you - it freezes so fast.<br> Down side is what's called 'low cycle fatigue'. The fuses get a trifle warm in normal use, expand, and then contract after they cool off. That repeated expansion/contraction causes microcraks to start in the lead alloy, which eventually propogates across teh wire till the fuse is intermittent, with a crack you need a magnifier to see. That's why it's easiest to just replace all the darned fuses after 8 or ten years - cheaper than spending time on diagnosis. Copper is much stronger, less sensitive to low cycle fatigue, but contains a lot more thermal energy when it blows.
 
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