280SEL ignition?

[n/a]

First off let me say hello,i'm RJ new to the board,i am a lover of all vintage german cars,and a small segment of new ones. I recently aquired a low mileage documented 1970 280SEL automatic on the tree for a good price, ofcourse here is the info for those waiting on the catch,it had been setting in a field for 20+,now before you say, whoa, let me explain, its condition is actually pretty good for a car that set that long,no structure rust, just cosmetic,no water damage other then the wood trim being a little damaged due to moisture,the odometer shows 53,000 and the documents that stayed with the car have visits to a mercedes shop up until about 47,000 of that, and that was in 78, it was parked in 81 due to a bank dispute and sat all that time until about 87 when the bank debt was cleared and it was sold to the previous owner,which let it set on a mountain in a field, which is why i think its not completely gone. I am the 3rd owner,with the minimal rust on the car its definately saveable,all the electrics work,windows lights etc...,the fuel pump horn and a few other items have suffered the test of time. Now to the question at hand,i cant for the life of me get the car to fire very strong, new points & condenser etc.., what i'm having a real problem with is that ancient ignition box,i am hoping the wires were replaced right,it has a spark but very weak,i've tried a different coil,but i think i've come to the conclusion that the ignition box is at fault,my question being is there a way to completely replace the box or an ignition upgrade Pertronix and the like...,i dont know much about these models when it comes down to model specific things,although i understand Bosch MFI,and intend to restore all injection components, i am aware that the SL of the same year shares the engine components,and that led me here in the hopes of getting advice on certain things. I realize that an already running 280SEL would be more cost affective to buy and keep up,but its a labor of love,there werent that many W108 SEL's made i believe it was somewhere in the 6800 ball park for the American market for the 280SEL,correct me if i'm wrong please,i refuse to let this great piece of history rust away over the years,i cant bring myself to sale it,so its staying,i'm sure all of you understand completely my devotion,so if you could help with my ignition question, i would be greatly appreciative,thanks for your time,and i hope i didnt ramble on too long......


          ,RJ

[Cees Klumper]

If I am not mistaken your W108 engine will be the same as the W113 280 SL's M130. You should be able to replace the ignition module (I think you are referring to the transistorized module that is very expensive to replace) and convert the ignition to electronic - try a search on this site since there are numerous posts relating to this issue.

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[n/a]

Thanks for the quick response,i have read around a bit and have found several posts on the subject but not my specific question,what i want to know is,is the ignition module completely bypassed,i'm just at odds with it, and what is the purpose of the several additional wires that are conected to the module,and the way the coil is connected puzzles me, its not like a traditional ground system,even most Bosch electronic systems that retained a traditional coil still hooked up with the traditional ground system,this coil is hooked to ground directly and has the power coming from the box i believe,very confusing,i'm just not familiar with this transistor setup i guess.


              ,RJ

[Ben]

Sorry I cant help with the ignition but one small piece of advice would be to ensure no sediment from the tank gets near the fuel pump or you WILL have problems...........expensive ones !

I would drain the tank and check the contents for rust and have it resealed, flush out the lines and change the fuel filter before attempting to start it at all !

Regards,
Ben in Ireland.
'64 230SL 4sp.

[n/a]

Well as stated the fuel pump was shot when i purchased it,i popped it open and cleaned it and got it working again,right now the car is partialy dismantled in the engine bay,and is ready for injection pump removal,i dont think it needs rebuilt,its just gummed up from years of non use, i'm going to give it a good cleaning and soaking,and check all the valves and rack for functionality, if it is savable,which i'm confident it is,i'll replace a couple things on the engine before reinstalation. For now though i plan to make a note of every mechanical defect and renew them as they come,as i said before the engine only has 53K miles on it and you can tell,so no major engine work should be needed,and even the auto trans looks cherry,with no sediment or metal debris in the pan, aswell as the oil in the engine case being right at the mark and silky smooth. So thats that apart from the aforementioned details its a pretty good resto project,good panels, and only a few places on the sheet were it will need some fabrication,knowing many excellent body welders, and a very experienced beetle owner, rust doesnt scare me one bit. I thank you for your advice,but am well aware of what sediment can do to a MFI system,hell any fuel injection system for that matter,i only wish it had a 4.5, although a vacuum pain D-Jet is much much easier to deal with.

          ,RJ

[ja17]

Hello RJ,
You are prbably at the best place for information with this group. The engines are virtually the same as is the ignition and suspension in most cases. In addition many other mechanical systems are identical. In fact these cars share the same factory service and repair manuals since most systems are so similar. The group has accumulated a vast amount of information for you to brouse through and the people are all great. I know of no groups  nearly as comprehensive in reguards to these nice 108 sedans.

A 280-SE, SEL is one of my all time favorite sedans. They still had nice hand built quality great engines and "living room" interiors with plenty of space and one of the most comfortable seating arrangements ever. They have very dignified and classic lines and were one of the last models before chrome, wood and leather began disappearing by acres.

The earlier cars did have non transistorized "standard ignitions (as did the SL). With the transistorized ignition the spark across the coil is weak since it is just a "switch" for the spark box (electronic ignition). Check spark at the coil by having someone crank the engine and holding the coil wire end near grounded metal.

Be sure to check the ignition wires with a ohm meter since the original ignition wires are solid copper they seldome fail. The screw on ends do go bad. Old points get tarnished from sitting a long time. On the electronic ingitions the points can look fine but this tarnish will insulate them enough to cause poor spark or none at all. Ceramic ballast resisitors can go bad (check these by temoratrily jumping across these.

I would make sure the fuel supply and filtering system is clean first with correct fuel pressure and quantity (lots of posts on this). Check plug wires and ends for resistance, replace plugs and points, chech for spark next. Maybe give it a squirt of fuel (from the intake starting solenoid or a squirt of starting fluid to see if it fires at some point.

The ignition can be made standard if all else fails and if you do not have the parts or resources to put it back. The other electronic units can be fitted up (lots of posts Crane, Petronix others). If you want to convert it to standard non-transistorized without electronics with just off the shelf auto parts store parts, you will need a different coil and the correct ballast resistor for the this non-transistorized ignition coil. The condensor can be re-wired to work like a standard one. The point configuration with the clip is typical of the transistorized cars. The non trans ignitions of the early cars had a fork terminal on the points. I believe an early
Bosch Volkswagon transport points were clip style, non-transistorized and fit and work fine.
It is easiest to fit the aftermarket electronic ignitions these days, but don't give up on the original because you do not understand it.

Good luck, welcome aboard and keep us up to date!


Joe Alexander
Blacklick, Ohio

[n/a]

Thanks for all the great support, and i'm very glad to be informed that this board is such a big resource to these cars, i have been inpressed by some of the great experts that our under some of the tech discussions. I am very mechanically inclined and am no stranger to the inner workings of german cars, but as any intelligent car enthuisiast should know, if you've never had experience with a certain model or make, get professional and most importantly experienced help from someone who knows the cars. I must admit that i wasnt a Mercedes fan until recently, mostly liked vintage VW's and Porsches, but as soon as i got one of my own i became hooked, theres just something about german cars from this era, the care and thought that went into them is just mindblowing, from the lowly beetle to the mighty and dignified 600 sedan germans just do it better. I should introduce myself properly since the response's to my post were so helpful and friendly, I am currently in college to become a Pharmacy Tech so my finace's arent exactly up to par right now, but i am a very determined person that never gives up on anything i do, so it will get done, maybe not as soon as i'd like. I also own a 63 beetle that will soon be going in for new heater channels and pans, and an extremly well used 68 280S that i am using as an introduction to the 108's, although it is far from a fuel injected 280SEL it is doing its job of introducing me to the model. Currently the carbs are on the waiting list of things to do,rebuild time is coming soon, as every car nut i never can have just one,so they all get a bit of my time. Well i guess thats enough rambling on for now, hope that gave you a general idea of who i am, oh and i am right below you Joe in believe it or not RockLick WV,there seem to be alot of Lick's on the east coast,lol.



            ,RJ

[ja17]

Hello RJ,
Your 68 280-S probably does have the non transistorized ignition as do the early W113 cars. I have a good carb rebuild procedure on those complex Zenith carbs on your 280-S if you need a copy. The W113 SL's always were injected although I did see a set of carbs from a sedan on a 230-SL one time! The injection pump was off being repaired and the customer was driving with carbs temporarily!


Joe Alexander
Blacklick, Ohio

[n/a]

I have a haynes and a big blue from late 69, so i have pretty detailed exploded views and rebuild info, i know what you mean about the Zenith's i wish they would have stuck with Solex, it would be a whole lot easier to maintain,but thanks for the offer,and yes the 280S does have a traditional ignition,but for now it'll stay on there,well i guess thats it for now,when i really start getting into everything i'll keep you updated.

           ,RJ