rayhennig

I hope this may help someone.

This is NOT related to a hot engine idle fluctuation that does still cause a stall from time to time, and did today during my test. More on this elsewhere - I suspect weak idle mixture.

This relates to a recent stalling-when-hot problem. Engine would misfire after, say, 15 minutes of warming up and then would die if revs fell, say, at a junction. It would then need around an hour to restart and then needed to be kept 'on the boil' to avoid stalling during rapid return home!

0. Car has 350 K Kms and 2 years ago had new distributor cap and rotor arm. I was in UK at the time, near Ashford, Kent where I bought low-cost Bremi parts from a discount motor store.
All was fine until recently (April 2009) when car died on me after not having been used for a few weeks.

1. I dismantled and cleaned the distributor cap and surroundings.

2. Re-assembled, tested and things seemed OK. Test only lasted an hour or so but involved heating things up and then stopping for 10 minutes before resuming. A week later, the same problem returned.

3. Ordered distributor internal shield and O-ring from Mercedes. Installed and it started immediately but after 10 minutes idling it started misfiring and then died.

4. Disconnected battery for 30 minutes (?) and re-tried – the same, it died again.

5. Replaced 'newish' Bremi rotor arm (easiest course) with cleaned up, ancient (original) Bosch part – this one had Mercedes star on it so may have been original 1991 part. Engine started immediately and settled into steady idle. Left it idling for 30 mins, never missed a beat.

6. Tested for nearly 2 hours including 30 minute stop and a few 5 minute stops. Restarting was better than ever and idling good. Low down torque also seems better.

All seems well now and confidence has returned.

I was tempted to strip out Bremi cap and replace with old Bosch original but ex-Army motor maintenance officer friend said, “Try it for a while.” I will try this but I'm tempted to go back to Bosch original that I've now cleaned up. It is ancient but it looks good after clean up although internal contacts are eroded.

When my economy improves I will almost certainly bight the bullet and get cap and rotor from Mercedes.

My friend did note that the old internal shield appeared to have been varnished and showed me how this stuff easily scraped off the surface. He said this was an army technique that he's used on distributor caps when no replacement part is available. Apparently it's good for quite a while but not a permanent fix. He aslo said he noticed evidence of 'tracking' on the shield and thought my new purchase was probably worthwhile.

This is not a dig at Bremi parts but I would like to hear of any other experiences with these after-market bits. Any comments?

As always, the best to all.

RayH

Brian_I.

Wow, I'm amazed at how exact your description of your problem is to the one I just started having on my wagon two days ago.

Is there any way you can dumb down the instructions on how to fix this? I feel like I'm reading German here but would like to see if this is something I could do on my own.

Thanks for taking the time to post this up. I couldn't have described my issue any better!

rayhennig

Hello Brian,

Please start from the beginning and describe your problem. Describe the problem in the following terms:

1. Engine hot or cold?

2. High speed or low speed?

3. Does the problem go away as it cools?

4. Is the car used 'stop/start' like, for me, in my London days. Or do you do 20 or 30 kms before switching off again?

5. Type of car, year, engine, fuel system, ignition etc. details. VIN number would help.

More than happy to comment.

All the best.

RayH

Brian_I.

Sorry Ray, I meant that I just don't understand it because I know nothing about what's under the hood other than the step-by-steps I read online.

1. Engine is usually cold because we don't use it at all except to move it around twice a week for street sweeping. It will start up fine enough for us to move it across the street but that's it. The other night I let it warm up for about 10 minutes while I did some stuff and by the time I went to actually move it, it starts to "flutter" and then just dies. Try turning it back on and it turns over but nothing.

2. The next day I was able to get it started and thought maybe it needs gas so I'll drive it to the gas station. Was doing fine driving at regular speeds then about 5 minutes into the drive it starts showing signs of hesitation at a stoplight and then within a few hundred feet (or maybe 30 seconds of driving) it dies and will not start again.

3. Definitely seems to go away since by the next day it starts up fine again. The shortest I've let it go between re-tries to start it up is about 10 hours or overnight.

4. For the past two years it has almost exclusively been used for short trips. My wife only drove it to get the kids from school and go to the market (all under 2 miles round trip). Every so often I would drive it out on the freeway to get it going but never longer than 15 minutes or 10 miles or so.

5. 1992 300TE WDBEA90D4NF203583

Again, thanks for being willing to help. This car is really stressing me out lately. I just wish it would run as good as it looks.

rayhennig

Back tomorrow when the Bergerac Red wine has worn off!

C'est la vie en France.

RayH

rayhennig

Brian,

Your VIN will read something like:

WDB 124 051 12 C4 27 904

The above example would be for a 300C£-24. Naturally, yours will be different but with similar grouping of fields.

Awaiting your advice.

RayH

rayhennig

Brian,

The attached shows my setup. If you have an early series M104 engine it will look loke this.

My numbering (1 to 5) is the order in whick things are removed.

I have replaced my items 3, 4 and 5.

Item 3 is still a cheap Bremi distributor cap and I intend to replace it with an MB original when I can.

Item 4, the rotor arm, was what caused the problem and I replaced the cheap Bremi with original MB and all seems better.

I also replaced Item 5 with an MB original and I haven't paid for it yet and, despite its being only a passive part, I fear it's going to be costly - more than 100 Euro - bad news.

My advice on using original MB parts is based on experience and the fact that things get pretty hot here. Unlike old distributors, this one is bolted on to the engine; hence the heat.

I believe the failing rotor arm was due to heat.

If your car matches this, then what I say may hold good for you. To do the work you will need Allen keys and little else. Be careful with re-assembly and don't force ANYTHING. I would also not recommend spraying any products into the distributor cap after replacing parts. I would advise lightly greasing screws before replacing.

If you have the M103 engine, it may be similar but I can't remember.

If you have the later M104 engine with more electronics, you won't have a distributor, it won't look like the picture and all I've said is irrelevant.

Open the bonnet, have a look and bon courage!

RayH

Brian_I.

Thank you Ray. I'm really not sure if this is something I can tackle on my own but I may try. I guess the hardest thing would be locating parts. Will see what I can find...

Thanks again for your help and the time you spent to put up all this information!

Brian_I.

Good news! I replaced the distributor cap, rotor and spark plugs (all OEM Bosch parts) and the car is running great so far. Idle is still a little lower than what would make me comfortable (around 700rpm) but does not hesitate at all at stops and ran fine on my test drive.

This weekend I'll be changing the oil/filter and the engine air filter.

appatula

Brian, your car is idling where it should be . If I recall correctly factory specs state that 650-700rpm is normal idling RPM.



Now time to put that extra Bosch rotor arm on, when I replaced the cap and wires the old rotor arm looked fine so I skipped it out.

Brian_I.

Can you expound on said rotor arm? I haven't heard of this before...

appatula

Rotor = Rotor Arm, vise versa. Different strokes for different folks.

Brian_I.

Oh got it!

I actually thought maybe you were talking about this Rotor Bracket

rayhennig

Brian,

As I understand it, you have replaced distributor cap and rotor arm and the thing now works, true?

If so, it sounds as if you had the same problem as I had - a rotor arm that breaks down at high temperature. I was going to put mine in the oven and measure it but I really have more interesting things to do so I threw away the cheap one.

If it's working, lie back and enjoy!

Well done that man.

RayH

NDavies4

I know it's nearly a year since these discussions but just wanted to say I have exactly the same issues on my W124 300-CE-24 cabrio: Works fine as long as I never leave it unused for 4+ days. If I do though (e.g. holidays) then it'll run for 10-15mins on first use, but then go into a rough idle and eventual stall...

Drove me crazy for a year or so back around 2004 but once I realised the problem was in the area of the distributor cap, I've simply learnt to live with it. What I do is remove the cap, spay some electrical contact cleaner in there, wipe it out so completely smear free (and the copper contact points have no deposits on them), then on re-assembly and all works fine.

I do though find that if the car's been unused for say 2 weeks, I have to do this exercise 2 or even 3 times in a half hour period before the has completely gone.

While I could continue in this way, I would dearly love to resolve the issue once and for all.

I take your point on replacing the dizzy cap, rotor arm and even back shield with proper Merc parts - all of mine have been replaced over the past few years, but none were genuine Merc parts (always seem so pricey - but maybe this was false economy!).

What has always puzzled me though is what physically happens to cause these issues - i.e. what is the difference between the car being left overnight (never a problem) and when it is left for a few days (always a problem!). I've seen similar discussions on other forum sites and the one thing in common always seems to be an M104 (CIS-E fuel system version) engine, as I think found on all the 300-24 variations of the W124 (plus maybe some other models).

Any thoughts much appreciated as I would love to understand what's really going on and what it is about the design of this particular engine that would appear to make it incompatible with non-genuine Merc parts.

Best regards,
Neil

rayhennig

You say that your's gives problems if left for a few days?

All I can say is that mine always started promptly even if it was left for 2 months, outside, in the rain, snow, freezing, sun, heat, humidity - you name it.

I put this down to the electrics being in good new condition. To recap, I have:

Bosch F8DC4 cheap, ordinary spark plugs - NOT resistor or exotic platimun types.

Beru HT cables - about 3 years old now.

Cheap Bremi distributor cap that will be replaced by a gen. MB one when funds allow.

Gen MB rotor arm, 1 year old.

Gen MB screen (behind rotor arm) - 2 years old.

That's it really but I do have a vacuum issue that gives some other grief but that's another story.

Happy to answer other questions if you have them.

RayH

DIMITRIAR

My 92'' 300ce-24 Coupe did had exactly this problem that you had recently.
After using the car as my everyday transport without any problems over a long period,i decided to garage it, keep it immaculate,and just enjoy it sparingly,while i use a small runabout i bought for the general day to day running around.
Upon garaging the Benz for periods of days and weeks at a time,i immediately started to get this rough running and dying out problem you described.
It drove me nuts for a while too,but after it left me stranded,i trucked it to my mechanic,and told him to keep it for a few days,drive it,and try and find whats causing this intermitant problem.
It was the filthy inards of the distributor cap,and i can't remember what brand he said it was,but he did say they had had problems with this brand in the past,so he replaced it with a brand new bosche,of which he recommended,and all has been sweet ever since.

encore300e

Mainly for the higher mileage cars. Mine is 200k's.
Recently, I have spent hours looking at Forums trying sort out the problems
with the K-Jetronic. There are many faults but one that comes up a lot is the stalling at intersection and traffic lights, especially if the engine is hot.


I had got most of the gremlins out of a car that I bought a couple of months ago but it still gave me grief at the lights. Then I had a brainwave.

I got it up to temperature, here at home, and then disconnected the small diameter hose at the valve cover; the other end connects to the inlet manifold so I had to block it to allow it to run. I started it up and it ran really smoothly. The bad gases coming out of the fitting in the valve cover were a product of blow-by and were now venting to atmosphere.
I took it for a drive and there was no hint of it hunting or threatening to stop.

At home again, I found a plastic tyre valve cap, the one you remove to inflate your tyres. I drilled a 4mm hole it and put it into that hose which I had blocked earlier.( I took that blockage out). Started it up again and it ran really well. I took it for a drive again and traffic lights were no longer a problem. A few times I had to look at the rev-counter to confirm it was running; it was (is) so smooth.


It's the same with the A/C on and the lowest idle speed I get is 600 RPM.
Well worth trying!.

wakalulu

The stalling at low idle and deceleration has been driving me nuts over the last few months, since the fuel pressure regulator was replaced. I have been chasing the issue all over the place, and just yesterday i was thinking about the venting valve too - reason being there are signs of oil dripping out of the hose connected to the air filter. I was wondering if either there was a blockage in the venting path, or perhaps the oil spillage is choking up the downstream parts.

I'm going to give this a try tomorrow and let you know!

encore300e

Hi. It will be interesting how much blow-by you see once you disconnect the hose. Don't forget to block the hose or the engine wont start.

skjolden

Brian,

Did you solve your issue. I have been reading through many online forums and this problem sounds exactly like mine as well. 95 E320 Estate. Recently it has started to stall on occasion when letting off gas, say when coming to a stop sign, or turning after a stop sign, or even sometime during highway cruising (where I suspect I have lightly backed off throttle to maintain constant speed during slight elevation change or to match speed of car I'm following). It will restart after a minute or two of rest. Other forums have suggested MAF, but I changed that with an OEM part and problem persists. Did you change rotor/arm/cap and that fixed it? Would love to know how/if you solved it. So many people on forums describing my problem, but yet to find someone who has correctly identified the solution.

Thanks, Erik