1995 C220D dragging in air.

[BrianA]

Good morning all,I hope you can help me out.
To begin, since I bought the car it has been pulling air in somewhere between (what I presume is) the fuel heater
attached to the engine block and the fuel filter.
The reason that I believe it is located around here is the fact that I can see the air being drawn in after I turn the engine off.
The air seems to start to be drawn from the filter but then again it also looks like it comes up from the fuel heater.
Anyway,I've had the inlet manifold off and given it a good cleaning as well as the breather pipes.
I've replaced the clips on the fuel pipe which takes fuel to the fuel heater from the metal fuel pipes
(though recently one went walkies and I replaced it with a slightly larger clip).
I have also doubled up on the o rings on the clear fuel pipe from the fuel heater to the filter and also from the fuel filter to the fuel pump.
I have also put a strip of gaffer tape around the lips of these pipes too.
Yet it still draws air in.
On my last two trips to work the car has cut out on me twice and give or take half a mile,in the same spot
after driving for roughly the same length of time.
I have replaced the fuel filter air filter and shoved some new oil in it too.
Could anyone tell me whether this could be air related (due to the fact that I put a slightly larger banjo clip on one of the fuel pipes) or whether it is something more sinister?
I think it is a dodgy/leaking fuel heater and have yet to bypass it to check.
Any ideas anyone,I am getting exasperated.
Cheers,
Bri.

 

[Dieselman]

With the engine idling give it a sharp rev, you should see a gush of air. Wherever you first see the air is where it's leaking.
As a first recomendation change the pipes, after that the fuel heater.

That should fix it.

As a temp measure just bypass any area you think is dodgy and see if it runs Ok.
Anything before the lift pump is under vacuum, anything after is under pressure. The lift pump is on the side of the main fuel pump.

 

[BrianA]

I stood watching it today Dieselman and the air started to appear from the fuel filter (the engine was off).
Also is it right that the fuel filter should be half full when I unscrew it within a half hour after parking up?
I don't think it is and more to the point how on earth does it get to be half full/empty when ther are no leaks evident and the inlet and outlet are at the top?
I'm going to bypass the fuel heater tomorrow I'll let you know how it goes.
I am right in saying that it's the fuel heater that's attached to the engine aren't I as I identified it from a description from a thread on here I think.
I put the old o-ring off the old fuel filter (the one that is around the threaded hole) on top of the new one,the idle was less rough but air still appeared after 30-40 minutes whilst standing,does this make any sense?
I know it's a lot of questions but I am truly grateful for the feedback.
If I don't sort it by January the 2nd 2007 it's going into the garage for a pressure test on the fuel line to see if it can be found that way.
Thanks for reading.
Bri.:bannana:

 

[BrianA]

I bypassed the fuel heater this afternoon so that the fuel was going directly into the fuel filter.
The car idled nicely so I took it out for a spin.
When I came to traffic lights it was mssing/hunting again and I could also feel the miss on the odd occassion under power.
Within 10 minutes of parking up I checked the fuel lines and the air is slowly creeping back towards the fuel tank yet I cannot see any bubbles coming up from the fuel pump towards the fuel filter.
It's all very confusing.

However while I was doing the bypass I noticed that there was some fluid underneath the fuel pump on a part of the chassis (directly below about 4 inches) I slid a finger over it and gave it a whiff and found that it is diesel.
I then wiped the bottom of the pump and found diesel there too.
All of the pipes I have been working on up above the pump are free from leaks as I've checked them time and again so is it possibly a loose injector pipe or two and will the tightening up bit have to be done from above or below if possible.

One other thing that caught my attention was the o-rings on the inlet manifold,are they supposed to be proud of the manifold so as to cause a seal when squished up and also is the appearance of them supposed to be flat or round?


Other than that the cars fuel consumption has improved since my first fill up when it was returning 37 mpg on an urban cycle and now it is 38.9 AND I put less fuel in litre wise.
Not bad for a 256951 mile car eh!

Cheers Bri

 

[Dieselman]

The fuel weep could be the shutoff valve seal leaking. Easy job. This could well be the cause of the poor idling as well.

 

[BrianA]

Engine shut off valve

The fuel weep could be the shutoff valve seal leaking. Easy job. This could well be the cause of the poor idling as well.

Not bumping here,I've just come off the phone with the local stealer and he said that he wasn't aware of my car having an engine shut off valve (My model).
The car is a W202 C220D...Non turbo.
I've ordered New fuel pipes from the heat exchanger to the fuel filter and fuel filter to fuel pump with all the new ends and and o rings included as well as a new heat exchanger gasket and Inlet manifold o rings and so far the huge bill is less than £20.

I've searched a lot of other forums without success I've read the Parrot of Doom "how to"(Great thread btw) on another forum but it's for a different engine.
If anyone can help with the part number or exact location of the shut off valve I would be truly grateful.
Many thanks.
Bri

 

[Dieselman]

If it doesn't have a shut off valve how does the engine stop. Ahh just got it, yours still has the older vacuum shutoff valve.

Ok so the fuel is probably leaking from the lift pump on the side of the main pump body.

 

[BrianA]

Pipes and o-rings

I changed the 2 clear fuel lines,replaced the inlet manifold o-rings,replaced the heat exchanger gasket and trimmed the end of a tatty fuel pipe today.
My car has just done 270,000 miles and here are a few pictures of an 11 year old inlet manifold o-ring and the new one.
The old one was like hard plastic and had shrunk.

The new one is the taller of the two above.

New one is nice and supple,hardly any pressure applied here.

I'm giving the old one a bit of pressure but all it did was creak,it would have snapped.
Hopefully replacing these will eliminate this mess

Note the black watery deposit that has leaked through the withered hard o-rings.

Here are some snaps of new and old pipes together to showthe difference in colour after a few years have elapsed.
The white ones are the new ones

I also trimmed down the tatty end of the thick black fuel pipe so that it fit nice and tight on the heat exchanger.

So everything got put back together,nicely tightened up etc.
The engine now runs almost as sweet as a nut (as they say)but....
It still has a little miss and air is getting dragged back into my new pipe after the car has been stood for half an hour.

Sorry about the picture quality below,but if you look you can see fuel trapped between air.

The air first appears from the fuel filter,and than another bubble appears from the heat exchanger,this takes approximately 40 minutes in total to happen.
I guess it must be the lift pump that you spoke about Dieselman.
But apparently it's integrated into the fuel pump.

All in all I'm pleased with the way the car is running now and for the sake of £21.98 I can't have done the car any harm.

If anyone has any schematics of my Lucas fuel pump or can point to where the Lift pump is it would be a great help.

Next week I'll show you how to make Lancashire Hotpot.

:bannana:Bri

 

[Wully]

Very informative post, thanks.

Hope you get to the bottom of the problem!

 

[Parrot of Doom]

Its similar to my experiences. I had a bad leak of diesel from the shutoff valve area. So I replaced 2 pipes that clip to the valve. The leak got worse. I replaced the shutoff valve O-ring (between the valve and pump). Then the remaining pipe to the shutoff valve started leaking. So I replaced that, and its fine.

I think you'll have to accept that you'll be replacing every single pipe and O-ring there is, because these things don't like being disturbed. You may well have fixed the original leak completely, but the higher pressure in the system now and the movement you created as you changed things has created other leaks!

Its all good fun though

 

[BrianA]

Its all good fun though

Thanks for that Mr Parrot,Im laughin me bleedin head off!!!!

 

[Parrot of Doom]

hahah you love it, go on!

You may find it easier if you park the car downhill on a slope.

 

[BrianA]

Hee hee.
Seriously,where can I find a replacement lift pump or a repair kit?

 

[Parrot of Doom]

http://www.mercedesshop.com/shopforum/showthread.php?t=173912

That may help, might save you a bob or two on any O-rings.

And reading the above, it may be worthwhile contacting Bosch directly. But I've never tried it so I can't say if it would work.

 

[BrianA]

Bumping my thread sorry

Now then,I've checked the senders from the fuel tank for leaks,
traced the fuel lines for leaks all the way up to where the metal fule pipe becomes a rubber one.
Took it off checked it for splits,renewed the banjo clips and still have no leaks.
So the leak is (Almost) definately where Diselman said it was and that is on the Fuel pump itself
as there is always a pool of diesel on the chassis.
I've checked (by the running of a finger) the pipe joints that feed the injector pipes and they are dry,
the fuel seem to be running along from the lift pump end of the pump.
Now if its the lift pump part of the fuel pump which I believe is built into the Fuel pump itself (Its a BOSCH) is it fixable by me?
Cheers Bri.

 

[Dieselman]

Anything should be fixable on the Bosch pump as parts are available.

Is yours a rotary pump with the injector pipes coming out of the end plate, if so the lift pump is inside. If it's an in line pump then the lift pump is on the side.
I suspect it's a rotary pump so it will need stripping down, although it's probably only an O ring leaking through the body of the pump.

Getting the pump off the engine is harder work than the stripping of the pump.

You need to disconnect all the fuel and injector lines, turn the engine to TDC then remove the vacuum pump.
Next remove the timing chain tensioner and all the bolts holding the pump on.

Support the timing chainand undo the centre nut from the timing mechanism and support the gear as you withdraw the pump.

You will need to maintain support for the chain all the time the pump is off the engine, otherwise the timing MIGHT slip.

 

[BrianA]

Thanks for the reply Dieselman.
It is the rotary type,now is there a main culprit of an o-ring or do I buy a pump specific (that seems onvious) kit?
Sorry to be a pain but I will post all my progress with pictures when I do it.
When you say MIGHT slip,why is might in bold?
Thanks again
Bri.

 

[Dieselman]

Because even if the chain goes slack the timing might not slip if you are careful when putting it back together.
Just be aware.

Take the pump to a diesel specialist, they will have all the parts required.

 

[simboson]

hey BrainA, how is your progress going fixing this fault im having the same nightmare here with my c220d auto, hope all works out

 

[Dieselman]

As mentined in another thread, eliminate all air ingress before going further, otherwise you are on a road to nowhere. (Which is different than a road to nowheresville).