I've had a warm start problem on our '91 300TE (125k mi) for years and have lived w/ it, as it seems just the nature of the M103, but now it is getting to the point where it practically won't start if it's warm (20sec of cranking & you have to bury the pedal before she'll stumble for a few seconds then roar to life). I've also noticed a gradual decrease in overall power over the last year or so. She downshifts on hills where she never did and just doesn't have the pull on on-ramps she used to. Runs & idles great otherwise.

I'm in the process of chasing down every warm start lead I can, throwing as few parts at it as possible and doing or sending it out for full diagnostics where feasable. Maybe my search can help others with the same problem.

Someone mentioned a possible gumming up of the fuel distributor. I have never heard of any FD failure in the M103 personally, has anyone else? Could this be the cause of the above symptoms & is there any way to test? We use injector cleaner regularly & 91 octane.

I remember when we did the head gasket @ 70 or 80k miles (?? have to look that # up) we had a bit of a warm start problem & replaced the injectors as part of the job & it helped a lot. ... Just musing...

Also, what are the odds of an intake manifold leak being the cause and where would it leak? How does one go about testing if the problem is caused by a rich (flood) condition or a lean condition?

Thanks!

__________________
Currently:
1972 350SL Euro 4spd
1973 BMW R75/5
1981 BMW R80GS
1995 FZJ80 with OM606 Conversion In Progress

From my experience its quite a common problem....I've had to replace 2 fuel distributors on seperate 300E's in the last two years.

Over a period of time they do get clogged with crud from the fuel lines, which leads to hard starting, uneven idle, stuttering from low revs etc.

You also tend to get overfuelling as a result, so it may be worthwhile pulling out the plugs after you have let the car idle for a period of time and see if any of the plugs are wet. If they are its a fair bet that the distributor is playing up.

Personally, I blame both replacements down to the fact that I used injector cleaner soon after buying each car....shortly after that the stuttering began. I can only presume that the injector cleaner scoured off the crud in the fuel lines which then got stuck in the distributor.

I got replacement distributors from Mercedes breakers and replaced them myself......they are not hard to change...just remember to fit a new "O" ring to the replacement distributor and never use fuel injector cleaner!!

PS: it can't have been the quality of the fuel that caused this for me, as we run on 95 Ron as standard over here.

__________________
Current Mercs
R129 1994 300-24SL
W124 320E Turbo Technics Twin Turbo 350bhp

Previous Mercs
W124 1986 Quad Cam AMG Hammer, 45,000 miles
W124 300E Turbo Technics Twin Turbo 320bhp
W124 E500