Hi, on the last drives the water temperature went up to 100ºC so i checked the fans and discovered that the plastic fuse body of the fan fuse had melted. The wire ends going into the screw terminals of the fuse box had been tinned by the factory and the tin solder being soft gave way over the years, creating a higher resistance which in turn heats up the brass fuse holders. (BTW, it is generally not a good idea to tin wire ends or solder crimp connectors for automotive applications). The recommended fix is to remove the wires from the screw terminals, clean the fuse holders with industrial contact cleaner and a wire brush and then to cut of the tinned end and reinstall the blank wires. Ideally you use non insulated wire end sleeves which are crimped to the wire end and result in a better and more robust contact surface. To identify a possible contact corrosion problem, check out the individual fuse mounts after a drive to check if they got warm or even hot. If the connection is good (no corrosion in the wire end/screw terminal or on the fuse holders) then the fuses/fuse holders should not get hot. If they are warm/hot, check and clean the wire ends/fuse holders as above. Good luck, Adrian
I was born with a soldering iron in my hand (Radio amateur back in time) and have therefor always preferred to solder wires before inserting them into a screw terminal or when making crimped connections. Even now when I know it's not good practice I find it difficult to alter my old habit. All the wires to the fuse board in my 246 L series are soldered, so I have quite a job coming up converting these (I hope they are long enough). But, following your recommendation, I feel very tempted to change my unhealthy behavior and do it the right way. Maybe a compromise will be to just solder the tip of the wire to avoid that ruffled look when you pull out the wire some day? Another alternative will be to crimp a sleeve on the wire as you mention. Do you have any pictures of such a sleeve and maybe a source for them as well? Best regards Peter
It's quite difficult to only cover the tip of a wire with tin due to the capillary effect of the wire strands, unfortunately. I've attached a picture of a blank wire ready for installation in the fuse block screw terminal, a wire with a crimped sleeve as well as some sleeves and the crimp tool (Knipex, my favorite tool brand for pliers). If you search for wire-end sleeves in 1.5mm2 and 2.5mm2, and a wire- or cable-end sleeve crimp tool on amazon or ebay you should find a bunch. A good crimping tool will start at 25-30, avoid cheaper ones as they usually don't really manage to create a good crimp connection. Crimping Pliers for end sleeves (ferrules) plastic coated 145 mm: Amazon.co.uk: DIY & Tools end sleeves non-insulated 1000pcs for 0.5-2.5mm2 wire | eBay I'm not with the car right now so there's only a picture from the workbench. In general this is a good idea, but with the soldered wire ends in the screw terminal the problem is that the soft tin creates an air gap between the screw and the wire which can't be fixed by applying Noalox. Image Unavailable, Please Login
For the guys in the USA: 97 61 145A Knipex 5.75 inch CRIMPING PLIERS - CABLE LINKS Regards, Alberto PS if someone has a USA source for the non insulated end sleeves, that would be great.
They seem to be called "Non insulated Ferrules" or "Crimp Sleeves" in the US MINI STARTER KITS - Ferrules and Crimping Tools - Largest Selection - Miromar Terminal Blocks - Accessories - Wire Ferrules | Connectors, Interconnects | DigiKey
Hi Adrian, While I fully agree with respect to tinning of wire ends intended for screw terminals, I am not sure what you mean with the other issue. I since long use crimp connectors (brass, professional, not that colored plastic stuff), first crimp them to the wire and finally solder the crimped region. Afterwards shrink hose is applied as necessary. My long term experiences are actually very good with this kind of fitting and contacting connectors to cables. What may be a drawback? Or did you mean to first tin the wire and then crimp the tinned wire? That indeed will make absolutely no sense. Cheers, Bernhard P.S.: checking the amp-meter, if fitted, for heating up is also a good idea. Even better to include a "service" thereof into the mayors. One will not be delighted, if small smoke clouds start emerging the dashboard . These heavy duty contacts are often neglected, oxidized and even may have come loose.
The drawback is that if you solder the crimped region, the tin will flow inside the wires due to the capillary effect and disable the flexibility of the individual strands after the crimped region. Such wires tend to break at the point where the inside tin flow stopped as the individual strands have no flexibility anymore to compensate vibrations and movement. A crimp connection done with the correct crimp tool (those run around $60-$150 per piece) is very robust and will rarely create any issues, so no need to solder. If you have access to a good thermal cam, have a look at your connections, fuse box, ampere meter, relays etc. after the car has been used for at least half an hour. You might discover a lot of areas where a good measure of contact spray and a brush can help a lot
05702 has red paint on the top of each fuse box terminal screw, anyone else have this or know why? Thank you Also 05702 had each wire tinned prior to secured at the terminal block Adrian, Any opinion on those type of fuses using Aluminum fuse metal; best to avoid? I heard they come from VW do Brasil (Pasadena Swap Meet chat) Image Unavailable, Please Login Image Unavailable, Please Login
Should not be a problem, but i would prefer copper. I think it's more important that the fuse body is ceramic like the original OEM ones and not plastic, which might melt
P.s. the red paint is screw lock varnish and was supposed to keep the screws in place. It should cover both the side of the screw and the terminal below.
