91 560 sel/145k mi
 

thanks for the reply its a 91 actually But I believe its timing as well.. Im just going to have it looked at by my Tech in Tulsa as wanted to in the beginning.. I don think I mentioned that the car smooths out after 40mph in a higher gear.. like there is no problem at all.. its just getting from a stop or simply just getting the car started seems to be the problem.. again wich seems to be a timing issue..Timing is the only thing left that has not been checked and thats because of the limited resources here Bartlesville pop
35000 I think that includes cows as well. At any rate we are getting spark from the coil and the wires and dist and we are getting good fuel quatntity and pressure as well.. and to further mystify the situation the car runs like a top at times.. wich to me and all my years of working on cars of all types(shade tree) says timing or sensor issue.. Im just concerned that its something more sinister.. but I will keep you posted.. thanks again for the reply

Peter,

Are you going to try a new crank sensor on yours? The suspense is killing me.

Mike

I have successfully avoided buying any more car parts this week, so didn't check in to see if the pickup fixed the problem. Will do so soon, what with all the cars I have something will need fixed soon....

Intermittant problems can drive you nuts -- it's usually fairly easy to find out why something doesn't work at all, but when it works sometimes and sometimes not, you have to actually catch it in the act with the correct equipment attached, and that gets to be quite a game.

A bad coil that gets hot can have it's internal resistance skyrocket, delivering poor spark, although I don't know if it will be late or not (the one I've been talking about has a new one). I suppose a dislocation of the crank position sensor or flags (or magnets?) could do this, but unless something is loose and flopping around, it's not likely to be intermittant!

The only other thing to check is wiring and connectors -- corroded or broken wires will cause all sorts of problems by being sometimes conductive and sometimes high resistance. Usually not a problem on a Benz, at least before 1994, but always possible. A big hassle, but may solve the problem (Hans has an S500 in at the moment that has a bad connection for the heater in the O2 sensor -- works fine once warm, but will set a check engine light periodically because the O2 sensor isn't hot at idle).

Peter

I liked 230/8's answer quite a bit. I think he is on to something, or else on something (only kidding).

Speaking of intermittent problems, that reminds me of a problem we had with a Pioneer cassette deck back in around 1980. It had a problem that would occur only every once in awhile. It was under warranty so we took it to the repair place. They had it for 3 weeks and finally said they had diagnosed it. So we went in to pick it up. The guy brings it out and shows us the paperwork. The diagnosis: "Intermittance" !! Later in life I became an electronics bench tech and I must have used that line a million times . "What's wrong?" "Well, looks like it has Intermittance"...

Mike

Problem solved!
 

Finally got to the "root" (or actually, ring gear) of this problem.

I'd always though something was fishy, and sure enough, when Hans finally convinced the owner to go ahead and have the tranny removed and car returned to the shop (Hans no longer does trannies on these cars since he works alone), the flywheel was indeed wront -- it appears that the ring gear was incorrectly installed 120 degrees off.

Ring gear is being R&R'd to reposition and Hans will get the car back shortly to tune up the ignition and fuel system (mostly new by now!).

I guess no one understood that a ring gear replacement requires removing the tranny, as all three owners were quite certain the transmission had never been out.

So this story has a happy ending -- and a caveat for other owners of similar cars: if it runs like crap after a ring gear replacement, the ring gear or slywheel was incorrectly installed! It's not necessary, nor particularly desirable, to install a Holley carb insted of the FI......

Peter

such a lesson in root cause
 

Incredible to imagine the work that went into resolving problems that didn't exist (fuel system work, etc)-- such a lesson in the value, and difficulty, of root-cause analysis in such complex mechanical systems. And a lesson why doing something off-the-track (like modifying the fuel system like I think was done here) is not a good practice since it flies in the face of resolving fundamental from-the-factory operation. Returning to fundamentals seems key in problems like this (from the distance my rookie mechanical mind can see and has experienced in much smaller increments vis-a-vis cars, very much the case though with complex computing systems in my experience by analogy).

i had a feeling about the flywheel. pity. good catch, chuck.

I would guess that the ring gear was replaced and it never ran right again, hence the conversion to a carburetor and replacement distributor. Didn't really fix the problem, and the current owner got it for a steal (less than $5000, I think, and it's mint except for the engine "problem").

Worth every penny, I don't think he's up to market value yet!

As my brother says, complex things fail in complex ways.....

Peter

Glad to hear your problem is resolved, very interesting reading, and I know you must be relieved, wish I would have run across this tech tip for you sooner. Check out this address:

www.mbz.org, click on articles, click on transmisson, click on moreadjust, click on 420 and 560 Engine Problems after Engine Installation

This seems to describe your same problem.

Brgds,

BENZSTER

Been there, done that...

Look here,http://www.peachparts.com/shopforum/showthread.php?t=90089

Problem Solved
 

Gentlemen, Thanks for all the advice. We have finally solved the problem.

The flywheel (ring gear) was indeed installed in the wrong position. When I purchased the car, the car was not running. I had asked the previous owner if the transmission had been removed and he said it had not. Now we know he had a memory lapse.
We wanted to eliminate everything we could before we pulled the transmission.

Thanks again I appreciate all the knowledge on the list. We put a lot of parts on this car but now I have a great 86, 560SL that I have just over $6,500 invested in.

Dave
86 560SL