would like help with ignition wiring diagram for 280SE 3.5 108.057

[280sl]

Hello everyone! Can anyone help me with a copy of the electrical ignition wiring diagram for a 3.5 280SE (108.057)? We changed a crankshaft seal and replaced a ballast resistor(original specs) in the car without altering anything, but a visiting mechanic commented that the ignition wiring was wrong and changed it himself without telling us. I don't know what he did exactly but now the car feels sluggish and slow to respond...which was different from before we did anything to the car. I don't know also if we did something wrong while putting her back together, but we checked the plugs and all the systems and they seem to be working fine..the car starts and idles okay (albeit a bit noisily on the driver's side bank of cylinders, as if the exhaust manifold was loose, but it wasn't), but when we get her running she's slow and sluggish to respond.

How do the V8s compare to the I6 in terms of response?(I know this is quite subjective for want of a quantifiable value) What i meant is that my I6(1968 280SE 108.018), is relatively smooth and quiet and quite responsive when to my throttle inputs, and i expect even more from the 3.5 V8, but its not happening.

Any help regarding the wiring diagram (even on ink and paper will do) and any other suggestions to get her running smooth is greatly greatly appreciated. I can turn a somewhat decent wrench but the extensive engineering of these old german leviathans often leave me flabbergasted and wary of doing anything to them, because i can't afford to cause more damage than i'm trying to fix!

I can't stand just looking at the car and not get her on the road. Thank you all!
please click on link for pics of my baby:
http://s27.photobucket.com/albums/c198/230CE

[Jengasan]

Hi 280

I 'THINK' I have a diagram in the MB service manual, I'm at work right now but I'll look when I get home for you and let you know. If I do, scanning it shouldn't be a big deal and I'll send it accordingly. In the mean time, I take it you've checked the firing order ? (Ht leads are always a favourite for 'experts' to change) It's cast into the rocker covers if in doubt. The M116 has plenty of torque and could easily be running on a couple of less cylinders than it should be though still getting you from A to B.

I have the same car, albeit a RHD UK model, and the ignition is generally a pig, which is a pity becuase it has to be spot on to work well with the D-Jet fuel system. Good luck and I'll be back when I've checked the manual.

Jengasan

[350SL4spd]

Have you considered switching over to a Pertronix ignition unit? It scraps the ballast resistors & expensive ignition control unit, exstensively simplifying the ignition system. Everyone who's converted on this forum loves it and claims, if nothing else, a seat-of-the-pants increase in power.

There are tons of threads on here about it if you just search.

Below is a rudimentary M116 ignition diagram that I had kicking around when I did the Pertronix conversion on mine. Maybe it helps...

[280sl]

Jengasan, 350SL4spd,
Thanks for the reply and the diagram...yup, i've checked the plug cables already and they're in the correct order. As of yesterday i've dropped the fuel tank and started cleaning it, replace the undercarriage fuel hoses and the filter as well and see how that goes. But i definitely want to reverify the ignition wiring.

Yup, been digging up a lot of readings regarding the Pertronix ignition, but i'm still not confident enough to take the leap...so as of now that particular project is still in the backburner.

Thanks again folks!

[cth350]

Careful here, there are 3 ways to wire a benz transistorized ignition in the early 70s.
The 3.5 sedans do it rather uniquely. For starters, the #1 line to the coil should be connected directly to ground, IF and ONLY IF, it's the original style ignition box.

If it was swapped out for the one in a 4.5 (or if that fool of a mechanic was too familiar with the 4.5's), then the wiring pattern is different, but the parts are essentially the same.

You don't need the schematic anywhere near as much as you need the ignition service pages from the 3.5/4.5 manual, which you should have at your bedside table for work like this.

You can purchase the service CD set for about 30$ by calling 1-800-for-merc.

-CTH
PS. Read your email from me.

[Jengasan]

280sl, hopefully with this post you will see a wiring diagram. Sorry it took so long but scanning it proved harder than I thought as it's an A3 page and I only have an A4 scanner. This means its in two halves and a key page but I hope you can follow what you need to. Good luck

Jengasan

[280sl]

thank you sirs cth350 and Jengasan! I didn't want to touch the car without something to look at, I just might make things worse.