Please take a minute to read this if you would and help diagnose the next step on my friends 96 E300D. The explanation is a little long but thorough as many of you like. Still seems like a fuel problem to me but at this point we would try anything. Do you think there is a chance it is the Tank screen? He is throwing allot on $$ at a never ending problem.
all opinions appreciated.................

MY Friend bought a 1996 E 300 Mercedes Diesel 6 cyl. Not turbocharged. The car is like new, with 105,000 miles. It came from an auction in Pennsylvania I think. When he test drove the car it ran like a Swiss watch. Four days later he went to drive it, and it wouldn’t start. It cranked four or five times until he felt sorry for the starter motor. Finally it started to hit on one cylinder and then two ,then four and finally on six. Then it ran like a Mercedes. It ran for three for four days and then wouldn’t start again, with out going through the same sequence. The days that it would run right were shorter when he parked the car facing up hill, than if he parked the facing downhill. He said It felt like the fuel was draining away from the engine. He had a Mercedes mechanic change the check valve by the injector pump, and put in a new fuel filter. It ran great for a week and then wouldn’t start. He then asked another mechanic who works on Mercedes and is really good at it, to see if he could find the problem. Mechanic said the fuel filter was filthy and the connection to the filter was loose. He replaced both of them. He also thought maybe the battery in the key might be weak. Battery was replaced. The car then ran great for ten days. Then it wouldn’t start. After going through the long cranking procedure , it started, and ran great at idle. The car had a miss from 1500 rpm to 3500 rpm and smoked blue fumes . It lacked accelerating power by missing., like it was running on 4 cylinders. When it finally reached 4000 rpm it quit smoking and ran smooth. He then took it to a Mercedes dealer and they said the fuel was filthy , and drained the tank and replaced the fuel filter for the third time. When he went to talk to them about their progress they said it was fixed and ready to go. He went out to drive it away. It wouldn’t start. They kept it for another week and replaced the fuel hoses both plastic and rubber to the fuel filter and replaced one of the other shot off valves. They called and said it was fixed... He went to get it and when they went to drive it out .. it wouldn’t start. They kept it another week saying it had water in the fuel line. They had it for one month now. He finally picked it up and drove it for a week and it ran great and then on day eight, it wouldn’t start. After the same routine of cranking ,it started and he took it back to the Mercedes dealer and they said they would find out what the problem was , but said they had no idea what it was. It is still at the dealer. My freind is waiting their call..

Thanks Bennett

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81' 240d 4 spd 140k on the clock

Does the car live in Utah like you do or elsewhere?

Assuming that no CEL is lit up....it sounds like it probably had more than one issue contributing to its problems originally.

First, drain what fuel is left in the tank and start off with fresh fuel and fresh filters (pre-filter and primary filter). Or, set up a secondary tank. See this post http://www.peachparts.com/shopforum/showthread.php?t=113596

Second, confirm ALL fuel lines leading to and from the IP and fuel filter housing have been replaced and that the large o-ring under the fuel pre-filter (has it's own part number ordered separately from the pre-filter) has also been replaced.

Third, confirm the GP's and GP relay and make certain both are operating properly.

After confirming the above I think you should look to the EGR and Resonance flaps in the intake concerning its inability to rev and that you take ANOTHER look at EVERY fuel line and O-RING in and around the IP and fuel filter housing for fuel LEAKS to resolve the hard starting issues. The two problems are generally separate issues.

Concerning rev's: the EGR or resonance flaps may be sticky or stuck. They can be cleaned. Screws up fuel/air ratios.

Leaking fuel line o-ring seals are usually responsible for hard starts. Starter has to turn IP until it has evacuated all air and re-primed itself in order for it to be able to start. Parking nose downhill usually helps and helps also with locating leaks.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

First follow the instructions for a Moly purge with clean # 2 Diesel (or Moly).

http://www.peachparts.com/shopforu...ght=300d+purge

If that doesn't "do It" ,...look to possible fuel contamination by Algae.

Yes the car is in Utah..

the leaking fuel line o-rings makes sense..

I'll check and see if the the mechanic addressed those issues

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81' 240d 4 spd 140k on the clock

My 96 did not start 2 weeks ago, then it finally did after what I assume was the starter pushing the air out of a line. I have been waiting for it to do it again before I take the intake off and dig deeper. Plus my shop manual has not arrived in the mail yet. (I do not want to get into that if it was just dirt in the fuel)
All the fuel lines and seals have been replaced on mine within 10k so I am still waiting but its starting great so far. I hope you do find what it is and please post when you do.
Most every post that I have read has been a fuel leak from one of the injector line seals when having starting issues.
Man having that many people look at it with the problem still going on he has to be pulling out his hair.

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1999 E300 TD 190,000
1996 Passat TDI 225,000-sold
1996 E300 120,000-sold
1998 Jetta TDI 186,000 -sold
1983 Chev Suburban C20 6.2-sold

Sounds to me like your friend has been receiving lots of excuses and not much actual repairwork.

There isn't much to stop a diesel engine from running. You need fuel, air, compression, and heat. Thats about it.

If theres a leak in the fuel delivery, it won't get fuel. You can tell by looking at the clear fuel pipes near the filter, if there are air bubbles in them while the engine is running, you have a leak. If theres fuel dripping from the underside of the shutoff valve, you have a leak. They're all easy enough to service, its DIY stuff, you don't need any special tools, perhaps a battery charger for when your battery runs out from all the cranking. The fuel system works under vacuum, so you won't see diesel spurting out anywhere. It'll just suck air in. Note that its normal to see a small bubble of air in the pipe that runs to the pre-filter when the engine is stopped. A small bubble that is, not a humungous great whacking 6 inches of air

The other suspect is obviously the glow plugs. They make it easier for the fuel to combust. If they're not working, you'll have a very hard time starting it, particularly in cold weather. The glow plug relay is mounted on the driver's side, near the top of the wheel arch. Small black box. Remove it, open it up, you'll see 6 large fuses - check they're intact. If the relay is working (check its getting 12V btw), then check the glow plugs. You can get to the first one, but the other 5 you'll need to remove the intake manifold - unless you test them from the glow plug relay.

Honestly, once you have a basic idea of how these engines run, they're pretty easy to fault find. Theres not much to go wrong.

Any updates on this? I suspect that it was something listed above, but it would be good to know what was wrong for informational purposes.

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1999 E300 TD 190,000
1996 Passat TDI 225,000-sold
1996 E300 120,000-sold
1998 Jetta TDI 186,000 -sold
1983 Chev Suburban C20 6.2-sold

The 606 diesel only has one fuel pump (at least the non turbo ones). It's small, and relatively cheap, and not hard to replace, especially if you are doing fuel lines. Replacing mine fixed a lot of funky operational problems.

Rgds,
Chris W.
'95 E300D, 228K

I am here to research the same problem on a 97 E300D. This is the same as your friends. I had a leak on the plastic fuel lines. My shop in HB CA replaced all of my lines and shut off valve ect.
Car ran like a champ. I am often on the road and my Benz sat in a drive way on a incline. I came home a month later and found small circle the size of your palm -of diesel. Car would not start. After jumping it and taking life off of the starter- it started. It ran rough for 5 minutes. I drove it for a week without issue. It also did not have anymore leaking (present in Driveway), but it smelled of diesel. Then I went on the road for a few weeks. Came back same dam problem. No engine code. This car only has 70K miles and I have factory service record for 65K of those miles. The Glow plugs were replaced at 61K so I know this is not my issue. Called the guys back in HB and they told me Air was the problem. Sure enough I popped the hood, and I could see air in my new clear fuel lines (the front one). So, this leak is not one way. A little diesel comes out and air goes in. I removed my window fluid resivore to get my head in there. I noticed I have a slight leak under my shut off valve. I am in phoenix and not southren Cal- other wise I would have the shop fix this for free, as they installed it. Does anyone know if there is an o-ring in this unit? Since its new I would suspect its okay- What is the torq spec? On another note, I can also smell the leak when you get out of the car.

Bill

Yes, an o-ring does seal the shut off valve to the IP. I think that one is o.d. 12mm x 2.5mm.

Use a little carb or other spray cleaner and clean the valve and the top of the IP and check it again to nail down where teh leak is comming from.

Unless very clean it is often difficult to tell if the leak is from the shut off valve, a fuel lines connecting to it or the delivery valves above it.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)