Don't tell SWMBA this but someone as smart as you are only unemployed because you want to be :>).
If you were here, I'd pay you $4 an hour to work on the golf course, you could quit when you got rich. Harry ----- Original Message ----- From: "Jim Cathey" <[EMAIL PROTECTED]> To: "Mercedes Discussion List" <[EMAIL PROTECTED]> Sent: Monday, April 10, 2006 11:10 AM Subject: [MBZ] 190D status (glow plugs today) > Replaced the bad #2 glow plug. I'd bought the replacement a long time > ago, the old plug measured some 30+ ohms, versus the 0.6 ohms it ought > to. Fortunately for me #2 is the one you can reach without taking off > the intake manifold, so it was fairly easy (a relative term!) to > replace. I almost blew it because I couldn't find my deep 12mm socket > and tried to make do with the regular one only half-engaged. After > rounding off the shoulder of the plug I looked harder, and eventually > found my set of deep metrics. That and a shot of PB and it came right > out. > > With all five plugs measuring reasonably I turned on the key, to find > no glow plug light and a harsh buzzing from under the hood. Tracking > it down resulted in finding that the GP relay (005 545 18 32) was > buzzing. I double-checked the wiring to it and its fuse, everything > looked good. No buzzing if the GP's were unplugged, and directly > jumping the ignition terminal at the relay resulted in the same > symptoms. I grabbed a spare 5-cylinder GP relay (Bosch, 002 545 06 > 32) from the parts pile, no doubt from some 123, and plugged it in its > place. It worked fine, though still didn't light the dash light > (which does work, I've gotten it to come on sometimes). So I'm going > to open up the relay and have a look. The 123 relay is non-optimal > because the mounting ears are on the wrong side. > > Inside the relay nothing looked obviously bad. I'll probably try a > resolder job on it, but first I have to strip the protective coating > off of the board. The current 'measuring' is somewhat elegantly done > by a reed switch. GP's #2-4 are fed through a single fat winding of > strap copper around the reed switch. GP #1 is fed through a narrower > counter-wound coil located inside the strap, it probably has three > turns (it's hard to see). If the GP's all draw equal current, the two > flux paths roughly cancel and the reed switch sees insignificant > magnetic flux and doesn't close. #5 is an obvious bag on the side, > and has its own reed switch with a 6-turn coil (in series with #5) > around it. One presumes that its switch is logically combined with > the other one to run the light. > > The stripping and resoldering went fine and the relay no longer > buzzes. But the dash light still doesn't go on. Probing shows that > both reed switches activate, and I think the main one is not supposed > to if everything is OK. I opened the Bosch relay and found that it's > built somewhat differently. There's only a single reed switch, with > two countered assymetrical windings. #1, again, is pitted against the > other four. (If you ask me, it's a better design.) > > The backwards housing can be corrected just by putting it back > together the other way around, so if I ever need to I can substitute > the 123 relay into the 201. > > On the bench, the repaired relay seems to work properly. With the > reed switch from #5 jumpered 'on', the lamp output goes high for > awhile when power is applied, then goes out. If the starter terminal > is momentarily powered the relay shuts off when the starter terminal > is released. The relay seems to be fine, so I reinstalled it in the > car. > > ...Which only leaves the glow plugs themselves. Measuring resistance > is only a poor substitute on high-current items like these. I grabbed > a big Cherry microswitch and two alligator leads, and the clamp-on > ammeter. I measured the current draw of each of the glow plugs in > turn, and found that all but #1 started off at about 25A and dropped > down to around 12A as it heated up. #1, however, started off at 40A > and dropped down to 25A. As it's drawing nearly 2x the current it > should, the magnetic circuit _is_ imbalanced and the light _should_ > be off. I'll have to order another glow plug for #1. But the car > should start anyway even if #1 is getting too hot! > > -- Jim > > > _______________________________________ > http://www.striplin.net > For new parts see official list sponsor: http://www.buymbparts.com/ > For used parts email [EMAIL PROTECTED] > > To Unsubscribe or change delivery options go to: > http://striplin.net/mailman/listinfo/mercedes_striplin.net >
