RKramkowski

I have a 1987 260e that decided to stop running. It was running fine and it was as if someone shut the key off. It was that abrupt. On taking the distributor cap off, I found the rotor in the condition in the picture. It was as if the contact was vaporized. I replaced the cap and rotor and it started but very, very hard. I'd have to crank for a very long time and eventually it might catch. I've even come close to draining the battery. I can generally use starter fluid and it'll start. Once started, it seems to run fine until I shut it off. Even when hot, it is very hard starting now. I didn't have this hard starting problem before the rotor issue. So I'm beginning to think the problems are related. Could I have a weak spark now, causing the hard starting? But then I'd think it would still start relatively easily if hot. But that's not the case. It's almost as if there were a current or voltage surge that caused the contact to vaporize in the first place. I didn't think the electrical output could get that high. Right now the cap and rotor are still OK but I'm now concerned that there is a different problem that caused the car to stop running and vaporize the contact in the first place. I'm not even sure where or how to start diagnosing this one. Any thoughts? I've never seen this on any car I've had or worked on in the last 40 or so years.

optimusprime m1

Check the back plate at the back of the distributor . This part stops damp or oil exiting the top of the engine in to the distributor itself.Or a bad carbon brush in the centre of the distributor cap .

RKramkowski

Thanks, I'll check that. I had already replaced the cap and rotor and cleaned the plate before your reply. I didn't notice anything suspicious but wasn't looking for anything at that point. With the new cap and rotor, it sometimes starts but is very, very hard starting. It generally won't start without some help (e.g. starting fluid). I haven't tried starting it again since your reply since I don't want to fry the new cap and rotor, too. I haven't pulled them again to check out the condition. But I want to try to diagnose the problem. Those caps and rotors aren't cheap!

RKramkowski

I'm finally getting back to troubleshooting after many weekends of rain or other activities. The plate looks fine but there are other symptoms of some sort of electrical problem. In the weeks leading up to this event, it would start but sounded like it was running on three cylinders for the first 15 seconds or so and then it would even out, firing on all cylinders and ran fine thereafter. This happened on every start regardless of whether the car was hot or cold.

I'm not familiar with troubleshooting a Mercedes, being much more familiar with American cars so I'm not sure how to troubleshoot this. If it were the OVP relay, I suspect it would either run or not (I have the single fuse relay and it isn't blown). If it were the coil, I'd also suspect it would either run or not.

The fact that it will start but after a lot of cranking and starting fluid leads me to believe it's probably something that is controlling the timing or spark advance. Does a 2.6 liter engine that old have crankshaft and/or camshaft position sensors? If so, how would I troubleshoot those? What else could affect spark and timing and how would I troubleshoot?

Thank!

optimusprime m1

Your right it will have the crank p- sensor located in the flywheel housing . Follow the cps lead from the ezl on the bulkhead it will go down by the oil filter its held in there with a cap screw .I would try a new 12 volt coil, it must be the same not one that looks like it ,go by the numbers on it.. The thing is you do need to find out just weather its fuel or spark problem . Thy make a tool for you to put in the ht lead and the end goes on the plug to see if it is firing every time .The spark can be seen through the side of the tool .Then if it misses a flash ,that will be the culprit at fault. As for fuel the pressure test is the only way to check it out .Have you a manual for the model w124? . I can send you one it will have all the checking data for the m103 2.6 .

RKramkowski

I'm guessing its not the CPS though or there shouldn't be any spark. When I attach a spark plug to the center post of the coil, I get a spark albeit not as strong as I would have expected. I would also have expected it to spark fairly consistently. But as I watch the spark while it's cranking, there seems to be gaps in the spark. That would lend credence to my starting issues that it doesn't seem to be firing on all cylinders as soon as it starts. I replace the coil from one I got from a salvage yard and it acted exactly the same so I'm guessing the coil isn't the issue. I'm going to try to find an EZL unit at a salvage yard. The challenge will be matching the exact part number and I don't want to spring for a new one in case that's not the problem. They are fairly expensive.

One other thing... I remember reading somewhere that if the OVP relay fails or is failing, odd electrical things could happen, including the SRS light coming on. Is this possible? My SRS light did come on awhile back (and stayed on) but I just chalked it up to a bad ground and was going to check all my ground points on the airbag, seatbelt retractors, and the SRS unit itself. I haven't done that yet so haven't eliminated that yet.

Oh, and I ordered a shop manual as well as Stu Ritter's Mercedes bible. They should be here this week.

optimusprime m1

I think ezl works or it wont. OVP can cuse a lot of problems .The chap that had the car before told me, that the engine had the head gasket replaced after this problem of starting up , like your having now.
And after it was started up after the rebuild it acted just as before .So they called an auto electric company in .Only to find the work that he had done was nothing to do with the engine.But down to the OVP relay .
Only one that came up trumps , was me . .As it had all new head gasket and valve work done before i had it . I will follow your progress . pm sent