2001 E320 CDI bleeding issues..

[Auto Poole]

Hi, I run a small garage in Tamworth, I took on this job for a friend, his fuel pump was leaking (the high pressure pump run off the timing chain on the front of the engine). I fitted a seal kit to the pump but it still leaked and upon further inspection found it to be cracked, so he bought a second hand pump and when I fitted it, no fuel would come out of the high pressure side, the low pressure side was bled, the pipes delivering fuel to the pump are clear so I can see there are no bubbles, but despite turning the engine over til I was pulling my hair out no fuel would come out of the pump.. So I decided the pump was faulty, perhaps a blocked one way valve, debris or whatever, so the supplier gave me another one, and ive had exactly the same problem with this pump.. Now the first pump I re sealed bled up and ran as normal so I know my bleeding method is correct and the engine does run. He is now sending me a third pump. If anybody can shed light on my problem I would be very grateful, ive been in the trade since I left school 13 years now, this issue has got me scratching my head.. This is the W210 engine, 3.2 straight six, 2001 model.
Many thanks, Auto Poole.

 

[scotty2hotty81]

You have probably got the 2 pipes the wrong way round on the left side of the pump as your looking at it.
There is no real bleeding method as cranking it over will make it start.

 

[Auto Poole]

Thanks for the reply, the pipes are on the right way, they are quite hard plastic and would need forcing to put them the wrong way, plus I have a white washer on the rear one so I know they are right. By bleeding method I mean cracking off the unions to ensure fuel to the rail then injectors.

 

[rpe2]

The only way to bleed the cdi engines is to keep cranking and cranking , no need to crack of any pipes. Note, you may need a spare battery/ booster pack.

Give the starter motor a rest every now and again.

 

[WG M-B]

You cannot crack injector pipes on a cdi engine. I will shut down

 

[hockeyanimal]

Are you sure you are getting drive to the pump?
If possible, (I'm not familular with the engine), can you drive it externally to check function, say out of a container feed it, hand operate, and into another container?

 

[Auto Poole]

WG M-B you cannot crack injector pipes? ... RPE 2 i've had the car linked to a running vehicle with jump leads and turned it over for hrs.. I know what you mean this is a self bleeding engine, but I've turned it over for so long there is def a fault. And I only hold the starter for 15 second intervals and let it cool, I don't want to burn out the starter. Hi hockey animal, i've checked the drive, it's good. And i've operated the pump on the bench with a drill with fuel pipes hooked up to it and no fuel moved through it, but it may need the pre pump in order to bleed, one theory I have is my pre pump could be a bit weak making it hard to bleed.

 

[OlafMaxwell]

My only recall on this is that I ran out of diesel one day and it took a lot of cranking to get the engine to fire. The manual instructs cranking as the method of bleeding the pump. I dont know the car well enough to know if there is any other likely cause, apart from the o rings maybe letting airlocks develop on the supply side.

 

[scotty2hotty81]

Does the drive side of the pump look like this? And you can mix the two pipes up, the ones that run under the pump that are clipped in to the head, did you do the filter? If so are you 100% it's sealed right?

 

[Auto Poole]

Olaf maxwell, I have replaced all the o rings in the low pressure side of the fuel system, there are no bubbles in the lines. Scotty, yes that's the pump i've got, i'm certain i've got the pipes the right way, i've put a new filter in when I changed the o rings and like I said no bubbles in the lines so yes its correctly sealed. Thanks for your input folks, my supplier is giving me a third pump tomorrow and my original leaky pump, so i'll hopefully have an answer for you before too long. .

 

[Auto Poole]

Ok so today I had my old leaky pump and another pump arrive, and unbelievably this third pump was the worst yet, it is full of crud and looks like it was stored at the bottom of a pond.. So I didn't waste any time fitting it. Just out of curiosity I fitted my old pump to see if it would run, and after turning it over for just 40 seconds it started. I can hardly believe I was supplied two faulty pumps and like I said the third is a waste of time. So I feel i've been led up the garden path so to speak by this supplier. My friend who owns this merc was trying to save money by getting a second hand pump, from the start I told him to get a recon pump with a warranty, we lost weeks on this venture and didn't end up saving in the end. Thanks for all suggestions and advice, this is a good forum .

 

[mersum1es]

I'm afraid you didn't get rid of the original leak, hp-pumps has tendency to leak only when cold. Of course if some of the seals (for example those low pressure lines) was not properly fit first time, but now they are? But let's hope everything is ok now, good luck!

When I was looking my W211 from Germany, I noticed from pictures that many cars had very rusty (outside) hp-pump?

 

[Frontstep]

When you strip the pumps that rust has travelled under the plates probably a cause of some of the leaks.

 

[Auto Poole]

Hi mersum, this 2001 model is rusting a bit now, to be honest I expect better rust protection from the Germans. And Front step, i've re sealed the pump and it's fine now but I did find the corrosion under the pump heads as you say.