fuel problems. help!

turbopete

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hi. can anyone help me. i have a 1999 E300 turbodiesel. having problems with air getting into the fuel when the engine isnt running. it fills the clear pipe, tank side of the pre filter, with a bubble of air about 1 inch (25mm) or so long. ive changed all 4 clear plastic pipes and seals leading to the alloy fuel filter housing. the air comes backwards from the pre filter side towards the tank. im wondering if theres maybe an alloy or copper washer missing from the 'bolt' that holds the fuel filter to its alloy housing? ive also got an annoying rattle from the engine at 1200 rpm and below. dealer told me its the injectors or at least 1 of them. can they be repaired at home or at least not by specialists? the car has 140,000 miles on the clock
 

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Can anyone help out on this one please
 

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Hi pete,

The diesel leak could be from the pre, filter itself which has a large rubber ring. There are rubber seals on the filter bolt, or could be the filter seal itself!

Is the rattle from the belt tensioner perhaps?
 
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turbopete

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Hi pete,

The diesel leak could be from the pre, filter itself which has a large rubber ring. There are rubber seals on the filter bolt, or could be the filter seal itself!

Is the rattle from the belt tensioner perhaps?

hi. rattle is definately coming from top of the engine. i originally thought tappets but they usually rattle all the time. pre filter has been replaced, as has the rubber ring. ive also replaced the fuel filter and the seal on the bolt. there was only 1. should there be 2? im a bit unsure as my previous 2 mercedes were 202 c class cars and both had untimely ends in life, so i never had to do much with them!
 

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The O ring which most people miss on these is the one between the shut-off valve and the injector pump.

The belt tensioner damper can make a real racket if the bush is worn - if you push hard on it with a block of wood while the engine's running (beware the fan), you may be able to temporarily silence it, confirming the diagnosis.
 
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turbopete

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thanks i will double check the tensioner. thought a tensioner problem would have got worse with more revs though. this rattles till 1200rpm then magically silences above that! wasnt sure how many seals should be on the bolt holding the fuel filter. diagram dealers gave me shows 2. mine only had 1 on and i replaced that as it was supplied with new filter. I think ive seen bubbles in the pipe from the shut-off valve now you mention it. theres 2 clear plastic pipes in that area of the engine bay i havent changed yet. none go to the filter housing directly.
 

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>>thought a tensioner problem would have got worse with more revs though

It can be a bit like a wheel balance problem which goes away when you drive through it, i.e., a resonance.

If the engine speed is coincident with a resonant frequency of the belt, the tension will change significantly and rapidly, and there will be plenty of work for the damper to do.
 

230K

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Hi

Are you having any fuel related running/starting problems or is the air bubble just annoying you???? My E300TD has always had that 1" of air that forms when switched off. I think they all (or many at least) do it.

230K
 
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turbopete

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no its not annoying me its not great to start, cranks over for a while then splutters into life, misfiring every now and again for maybe a minute or so, almost like a little cough, till the air goes through the system, then its fine till you switch it off. the misfire only seems to occur when the engine is cold. heater plugs are fine. i checked them a couple of weeks back. engine hot, switch off, let stand for, say, 10 mins, and cranks over again 4 quite a while. much longer than my 2 previous w202 c class diesels. seems to run fine once its going though. maybe a little less nippy than id expected compared to my c250 td and not great on fuel, but given the engine etc its about what i expected i think. not sure what these should be like on fuel really. its had this fuelling problem since ive had it but i was always to busy working to do anything about it. now im not working and the problem is annoying me!
 

230K

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Aghh

With those symptoms she must be taking air somewhere, if you have all o rings and pipes changed there is a non return valve kit and solenoid that you can fit supplied by Mercedes which helps.

230K
 
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i wondered about non return valves etc. only other thing i can think of is if theres a seal missing from the fuel filter bolt. a diagram from local dealer parts dept. shows 2 for it. mine just has 1 fitted. should there be 2 or is 1 just a different version of the other for whatever reason? any idea on part numbers and prices for the non return valve kit etc? and what does the solenoid do? dont quite get why theres another solenoid available coz its not an electric lift pump. or if it is its managing to run without any fuses in the fuseboxes!!!
 
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turbopete

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cheers mate. new filter was genuine from local main dealer, sealed in box and everything, but just had 1 seal in it! looking at pics, im sure the diagram they gave me for my car based on chassis no was the right hand side 1. so far ive replaced th end of the laeak off pipe (149) the leak off pipes themselves (146) filter and seal it came with (8 & 11) pre filter and seal (26 & 29) and pipes with new seals at each end (32, 83, 95 & 56) think im gonna order both seals for that filter bolt. maybe i will improve the fuel consumption too! get 20 mpg at best in town, when traffic is flowing! goes up to about 30 mpg on motorway at 80! not sure how close to right that is. its starting it thats my main problem though
 

230K

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Hi

Non return valve kit is B66548198 £27 from Inchape MERCEDES

230K
 
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turbopete

turbopete

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cheers for that 230K. update regarding rattle thought to be injectors. used a sledgehammer shaft (only wood i could lay hands on) and pushed down on fan belt tensioner where it hadnt belt running past. (towards the drivers side wing of the belt) pushed down till front of car sunk approx 10 - 20 mm on its suspension. rattle was exactly the same. im therefore assuming tensioner is ok. also assuming timing chain, guides etc are fine at 140k, so would next step be to slacken injector pipes with engine running to see which one(s) makes it go quiet? or does anyone know of anything else to check first? sounds like a tractor up to 1200 rpm then its sweet!
 

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Yes, slackening the pipes one at a time is a good way to see if it's a particular cylinder.

When I had new nozzles fitted in my 1995 E300D, it cost me £200 for the 6 of them - although the nozzles will be slightly different in your turbo-diesel, it's fundamentally the same injector, so, I would be surprised if the cost differed significantly.

There's quite a bit of stripping down needed to get to the injectors if you need to remove them (don't be tempted to bend the injector pipes to remove them!), and so, I'm sure you'll find lots of little jobs to do during the work. Replacing the by now brittle clamps for the injector pipes is an obvious job that costs pennies, but can save you lots of hassle later on.
 
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where did you get the injectors for your car? im up in cumbria and i was told they were about £160 EACH! as you can imagine, i was reluctant to splash out on even 1 at that price if its avoidable! as for hassle with pipes, shouldnt be too much of a problem to replace pipes in correct place if the plastic clips break (i worked as a mechanic for about 14 years) but ive heard the pipes are prone to snapping if the clips arent there. does anyone know if this is true?
 

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I had just the nozzles replaced - they fit inside the injecotr body. I can imagine £160 for a complete injector is about right, but, you probably don't need new complete injectors even if you find a problem - it's usually a problem with the nozzles themselves.

If you look for a local diesel injection specialist, they should be able to do the work for you, and set up the injector opening pressures correctly. The injectors aren't particularly unusual or difficult.

The injector pipes are prone to fatigue failure caused by vibration, and the plastic clamps are important in reducing the vibration - in a more technical sense, they seperate the pipe into shorter lengths between supports, thus raising the resonant frequency of the assembly. Imagine if the pipes were completely unsupported for their run of, say, 300 mm. They would probably begin to resonate at, say, 20 to 30 cycles per second (1200 - 1800 rpm). With clamps, the resonant frequency will jump up to a few hundred cycles per minute, outside the range where they will be excited.

I've seen plenty of injector pipe failures on HGVs, and so, it does happen - usually, you get a fatigue crack at the point where the pipe end widens to form the flare.

In short, the plastic clamps cost pennies, while each injector pipe costs over £30. Leaving the clamps off, or broken is not a shrewd move!
 
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thats what i thought. i know a guy who is a small 1 man operation diesel specialist. total fusspot. everything has to be perfect. no bad fault though. ive changed pipes myself on bigger engines. wasnt sure the small stuff hadthe same problem but for the sake of a couple of quid, why risk it? i'll chech the injectors to make sure that is the problem 1st then get some prices from my man in the know for nozzles etc. any idea how i can tell which type of injector it has? i know from past experience his book doesnt list an in line pump for my car, which its got, so i presume the injectors, or the make of injector could be different? cheers.
 
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