HELP!!! Desperately seeking sound advice to resolve turbo diesel Baby Benz issues. My folks are visiting, having driven Dad's 1987 190D 2.5 Turbo from the mid-west here to the Rocky Mountain west. The car is an automatic with ca. 235K. The car has always been serviced by certified MB mechanic and properly maintained. We are the second owners. They experienced NO problems enroute, but once here the following problems began:

• Fluctuating curb-side idle (sometimes nothing, sometimes a little & mostly a lot).
• Once hot (even within a few miles) the car will usually not restart.
• If it does restart, requiring a great deal of cranking over, the idle is very weak, fluctuating considerably & often stalling out.
• Around town driving is barely possible, requiring double-footed driving or the car will stall at every stop.
• Cold-cranking the car is perfect, with the car starting immediately after glowing.
• Once the car cools down (two-three hours) the car will always restart flawlessly.
• The car can be driven at normal or highway speeds with no problems what-so-ever as long as no stops are made. However, if the car is highway driven and one must stop for a traffic jam, the car will stall & possibly restart, but with great difficulty.

Dad & I have preformed the following services at dealer & independent mechanic's recommendation:

• Replaced primary & secondary fuel filters.
• Tested & confirmed operation of altitude compensator (mounted behind battery).
• Tested & confirmed operation of overload protection relay (mounted behind battery).
• Removed fuel tank to check for debris/algae. Replaced old, but clean fuel tank screen.
• Removed fuel thermostat housing & replaced faulty 'O'ring & plastic cover with fuel nipple (mounted lower DS below inj.pump).
• Removed & inspected injection pump fuel delivery pump (mounted lower DS on inj.pump). Pump was clean with seals appearing intact.
• Removed & cleaned intake manifold mounted turbo pressure switch.
• Vaccuum tested fuel shut-off diaphragm (mounted on top rear of inj.pump).
• Replaced all rubber lines between fuel thermostat housing, fuel pump & fuel heat exchanger.
• Unplugged idle control solenoid (per dealer suggestion) to see if car dropped to low, steady (non-fluctuating) idle, which it did. (Solenoid is mounted on very rear of inj.pump.)

Is there something we've over-looked?? What else could be causing these problems?? We've hopefully ruled out the injection pump as well after consulting several diesel injection professionals (Diesel Injection Service, STL, two Denver MB dealers, two independent MB shops & an inj. pump rebuilding company in Albuquerque, NM) who have told us that between them, they've only experienced two defective/failed injection pumps at that mileage. Short of an expensive visit to the dealer/MB shop, we're hoping to resolve this issue ourselves. Your input would be greatly appreciated so the folks can finally return home.

This same information was posted on the MBCA Tech Forum, but with no substantial results. Hoping someone here can come up with a final, sound solution to these aggrevating problems.

Sounds like classic fuel starvation.

If you're confident that the fuel filters are clean, then you want to concentrate on the fuel-tank strainer and the fuel-tank vent. Try a run with the fuel cap off, if that doesn't fix it, it's likely a clogged fuel-tank strainer.

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Gone to the dark side

- Jeff

Sounds to me like there's a problem with the idle controller. If you leave it unplugged, does the car quit stalling and having hot start problems?

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

Babymog-
Thanks for the speedy reply. As I said in the posting, we did remove the tank and replaced the fuel-tank strainer even though the original was very clean to begin with. You are not the first to suggest running the car with the fuel cap off. Will try that here very shortly. Keeping our fingers crossed.

Skippy-
Thanks for the reply. The only test we did with respect to the idle control solenoid mounted on the rear of the IP, was to unplug it with the car running. The fluctuating idle did cease, but we have not driven the car with it unplugged because the car idles so low it stalls. Will try to unplug it once the car is hot to see if you may be on the right track.

Even though you've checked the seals visually on the delivery pump, I wonder if it could be sucking air or failing to deliver enough fuel when hot. Also, I wonder if the pressure regulating valve in the outlet of the IP gallery may have failed leading to insufficient fuel pressure.

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1987 W201 190D

I doubt the idle controller. Even if it has failed and the idle is low enough without it for the engine to stall, hot restarts should not be a problem at all.

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1987 W201 190D

Don't forget you're in the rockies, perhaps the altitude has something to do with it?

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

Thanks for your input. We already thought of that possibility and as I posted, we did remove and test the altitude compensator, which is operating properly. Typically if there is an altitude related issue with a diesel it results in lack of power & excessive exhaust smoke, neither of which are a problem.

It sounds to me like you are getting air into the system when it is warmed up..enough that is won't start. Likely, when cold, fuel coming from the tank might fill the air gap and allow enough fuel to start and run well. Unfortunately, you have already adressed the fuel thermostat, which would have been my suggestion.

How much air is visible in your clear pre-filter? There should only be a small bubble riding at the top.

Maybe try turning up the mechanical idle setting? That way it will still run at an acceptable rpm, regardless of whether the ELR is working or not.

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Dan
2005 E320 CDI - 246k
1987 300SDL TD05-16g, Herlevi pump, Elbe manifold, 2.47 LSD - 213k
Past: 1987 300D - 264k

If it is starting properly after sitting for a while, it is not air intrusion into the fuel. The severity of the problem seems inversely proportional to the amount of time the engine is off, which is typical of what I've seen in fuel starvation (filters usually).

__________________

Gone to the dark side

- Jeff

What is the temperature where you are? If it's really cold, It could be fuel gelling? They did drive from a warmer climate.

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For Sale: 1982 MB 300TD
1995 Chevrolet Suburban 6.5TD

Sold: 1980 IH Scout Traveler- Nissan SD33T Diesel

Actually, quite the opposite Bajaman. Missouri has been & is far colder thanks to the humid climate & greater distance from the sun. Here, even with the cold nights and frequent & deep snows, we warm up very nicely. Today, for example is 68 degrees and sunny. Fuel jelling is not an issue given the restart problem only occurs when the car is hot, not cold. Thanks.

Why are you "bolding" everything. Online that is almost like yelling........

On a brighter note, you did a very thorough battery of testing, and spelled out your tests and results extremely well. Somebody more familiar with these cars should be greatly assisted with your information.

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

That was going to be my recommendation (to check the cap on the fuel tank to see if it has suction. Also, if the fuel line (rigid line from tank) is plugged with some debris (algae, etc) the symptoms are that the engine can start and run until the fuel in the filter and IP gets used up and the engine becomes starved. If the fuel tank has any suction it prevents fuel from filling the IP.

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!