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#1
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Defective BOSCH parts?!?
I'm continuing my posting from an old thread about a "missing" problem with my '95 E420.
I had a dealer mechanic take a peak at the problem that I was having (following the replacement of caps, rotors and plug wires). Initially we were planning on inspecting the vacuums by spraying them down with brake fluid. BUT, considering that none of these problems had started prior to swapping the new parts, he decided to inspect the new caps by spraying them down with brake fluid and seeing how the engine performed. Following the soak, the engine started missing like crazy and with the lights off in the garage you could clearly see sparks arching between the wires on the cap. (Not supposed to happen because the caps/wires should all be insulated ) We swapped back the old original caps and performed the same test problem free. The car runs great! Caps, rotors and plug-wires are all Bosch and ordered from Importec. Has anyone EVER heard of defective Bosch parts before? Caps?? Of the 30 years he's been a mechanic, he's never seen a problem like this. This has caused me 2 months of headaches and I'm beside myself to say the least. Any input would be appreciated.
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1995 E420 1998 SL500 Sport 2009 E350 Sport 1995 S500 Coupe 1992 500 SEL |
#2
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Were they really OE Bosch OR knock-off's from China.
Right now Bosch seems to have the rotors on back-order & even the dealers are selling Duduco!!
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MERCEDES Benz Master Guild Technician (6 TIMES) ASE Master Technician Mercedes Benz Star Technician (2 times) 44 years foreign automotive repair 27 Years M.B. Shop foreman (dealer) MB technical information Specialist (15 years) 190E 2.3 16V ITS SCCA race car (sold) 1986 190E 2.3 16V 2.5 (sold) Retired Moderator |
#3
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They're Bosch (Made in Spain) DOC, have you done a test like this? Is there another way to test the caps to ensure that they are in fact faulty?
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1995 E420 1998 SL500 Sport 2009 E350 Sport 1995 S500 Coupe 1992 500 SEL |
#4
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That is a pretty interesting test, spraying them with brake fluid? I have never heard of that one. Has anyone ever heard of that? Anyway, the only bad cap I ever saw had arcing like you describe and carbon tracks on the inside just like they show in the Chilton manual. But I didn't put any brake fluid on it!
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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine) 1988 F150 144,000 miles (leaks all the colors of the rainbow) Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra |
#5
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I'm sure he means brake clean.
but neither should be used. Brake clean does nasty stuff to plastics.
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-1983 VW Rabbit LS Diesel (5speed, VNT/Giles build) |
#6
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I wouldn't use Bosch parts on my lawnmower. Don't laugh, Bosch sells a fancy lawn and garden sparkplug at Lowe's.
I use a spray bottle of plain water, like another poster mentioned, brake cleaner is nasty for plastics. |
#7
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How did the engine not have a missfire with the old parts reinstalled? Ditto the comments about the brake fluid or cleaner. I think NGK plugs and Beru wires are better the Bosch. Good Luck.
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#8
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defective wires-yes. caps-no. that's a new 1. especially 2 new caps. i wouldn't put bosch wires on a bicycle. had lotsa problems with them. 3 sets right out of the box that i installed and a 4th where the cust did the job and brought it to me because it wouldn't start. bad coil wire. i would have like to have seen the light show on your car. i would think the new wires did not seat properly on the new cap and the spark was escaping that way. otherwise, there would had to have been lots cracks, pinholes, etc. to allow the new caps to leak spark. if the caps weren't such a bear to get on with proper wire routing, i'd like to see them on another car, with oe or someone else besides bosch wires. when i say oe, i mean factory, not oe mb wires from the dealer. those were bosch in the box at 1 time and 2 of the 4 sets i had problems with. good luck, chuck.
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#9
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I remember when you could buy a "Bosch" part and look at the box and in fine print it would say "Robert L. Bosch". My understanding was that "Robert L. Bosch" was an American company that used cheap foreign parts. We saw a lot of problems with them. Maybe they are still around and selling parts made in China with lead in them. They put it in everything else they make.
Just a thought. Paul
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84 500 SEL (307,xxx miles) |
#10
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Quote:
Maybe the AMF sensor needs to be cleaned? |
#11
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i'll say it again, bosch wires can be a problem out of the box. a miss at idle is a problem i've had with defective new wires. have the ignition scoped by a shop and make sure they're ok. no funny patterns. good luck, chuck.
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