Jim, Make sure you have your cluster pulling hooks handy, as they make an excellent tool for pulling those loops from the seat cover through the pad while you hook them or insert the nylon wedges.
It’s pretty cool how they arrange to get the upholstery to do what it does with a bunch of hooks or loops and wedges. -D > On Nov 16, 2020, at 12:52 PM, Jim Cathey via Mercedes <mercedes@okiebenz.com> > wrote: > > Jill's been driving the 2000 E320 AWD sedan as a replacement for the > BMW X5. (Which we still have, for now.) All's well, and it's wearing a > brand-new set of studded 16" Hakkapeliittas, but the lack of a > driver's-seat heater is coming to the fore. Well, that was the last > thing on the list, so I guess it's time. > > I removed the driver's seat, and peeled the seatback cover off. Not > Easy. The hardest part was unclipping the plastic hooks that pull the > cover (via heavy wire sewn into the cover) back against the pad and > springs. (I also broke the plastic headrest sockets, as I couldn't > see how to get them to release.) The broken seat heater seems to > start with a fine braided copper wire, looking something like solder > wick, molded into the foam, which morphs at some point to a thin (30+ > gauge) blue insulated ultra-fine tinned copper stranded wire that > weaves throughout the foam in the back. (The blue insulation is thin > and tough, reminding me of wire-wrap wire rather than the usual soft > PVC.) Peeling back the bolster where the cut in the leather was, I > could see where the wire was broken in that area. Only one side had > continuity to one of the terminals, which means there is more than one > break. Great. > > The design is bad. While the serpentine wire is closer to the human > body, and thus can provide heat quicker and over a larger area than > the older separate heating pads, it's very vulnerable to damage, and a > poor design choice for long-term reliability. I think that only the > W210 used this kind of design, and they went back to separate pads in > subsequent models. I think that if they'd used wire of twice the > gauge, and twice the length, that it would have held up to the > physical stress much better. > > I chased the wire around the offending outboard bolster, using a razor > blade to cut it out of the pad, and found all the breaks. Cutting out the > bad spot and soldering the ends together works well. I had one break > to repair, and one accidental cut. After that the whole panel had continuity, > and seemed to heat well when hooked to the (larger) bench power supply. > I'm running a 5A test current. I used duct tape to secure the wire back > into the pad. > > While it was 'burning in', I turned the seat cover inside out at the > tear (that was over the heater break) and got the lips of the tear > closed up. I used duct tape to secure the face into position, then > cut a piece of chamois cloth (leather-like, tough, water tolerant) to > cover the tear. I used black weatherstrip cement to cover the > chamois, then pressed it into place over the tear on the back side. I > then sandwiched the repair between two small anvils to press it flat > while the glue dried. > > During all this the current through the heater became intermittent, > chopping in and out, and gradually getting worse. Arcing? Eventually > it failed altogether. Not Good! This does not bode well for a > semi-permanent repair. > > The tear repair looked pretty good the next day, I guess we'll see how > (if?) it holds up with time. There is a worse tear at the piping of > the side seam that I still have to figure out what to do with. > > I began chasing down the new break in the heater. The problem lay > between the two earlier repairs, in the high-stress bolster, so I > began cutting more wire out of the pad between them. I eventually > found a slightly discolored place that seemed to be the new break. I > cut it out and stripped back the ends and soldered them. (The wire is > embedded in a wavy pattern, so it's easy to get a little slack to work > with.) Once repaired I could again apply the 5A burn-in current, > we'll let it cook for the day. > > Assuming it passes testing I still have to re-assemble the seat back, > then do the same thing to the bottom cushion. > > > _______________________________________ > http://www.okiebenz.com > > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
