E250 diesel injector problems

[jaymanek]

Hi guys,

this is one probably for dieselman but any input appreciated.

got a 97 E250 here.. We found diesel leaking from the injector area. All the injector wells were full of diesel.

We thought there was a problem with the leak off pipes so replaced, but it seems that mercedes pipes are thinner than every other make so the universal ones we used just keep popping off.

Anyway, the question is... there seems to be a lot of pressure running through the run off pipes.. is this normal? If not what could be the cause...

Mechanics seem to think maybe blocked injectors, but car runs ok and dont really want to pay £40+ each (and two days) to refurbish the injectors if its not likely to be the problem?!!

Any thoughts anyone??

 

[Mercedes cozy]

you could get the injector tested rather than buying. Cheaper.

But I think the normal way of finding out if the injector is blocked, you would get a slight knocking sound and also smoke.

It would be best to get a meter long leek off pipe from the dealer and cut it down to size to fit the injectors and see if that works.

What about your diesel filter, is that OK.
There are I think 2 filters, one is a canistor and the other is a inline filter normaly fitted within the canistor housing.

 

[Dieselman]

The performance of the injectors and the leak off pipes are not really related.
The leak offs should return the fuel to the tank at low pressure with the return to the tank under no pressure at all. I wonder if the return pipe is blocked or kinked.
As you can probably see the leak off pipes join the small bore tapping from the fuel filter and the pump return pipe.
Try blanking the other returns and run the injector leakoffs into a jar. The volume should be very low. Also try blowing back up the return pipe to make sure it's not blocked.
Get leak off pipe from your local Boshc diesel specialist, the'll probably give it to you.
You could have the injectors tested but I doubt it will reveal anything. My local diesel centre will test for free and are only about a tenner per tip for renewal.

 

[jaymanek]

Yes had the injectors tested, only slight blockage they said.
We already tried the leak off pipes into a jar thing, but NOTHING came out of them, its really weird. We thought maybe the leak offs on the injectors must be blocked, but all of them?!

the return to the tank doesnt seem to be blocked..

Anyway, after talking to a lot of local specialists we are getting nowhere so I ordered 5 new injectors...

Will get them tomorrow... I really hope this solves it as the cost is adding up!!

 

[Dieselman]

I really doubt it's the injectors, if the injector leakoffs were blocked then there would be nothing returning so no pressure at all. The leak off is only for any fluid that passes the pintle, which will be literally nothing.

UIf you pull off the pipe from the no1 injector you will see whether the fuel is coming from the injector or the filter head.

The main volume of fluid comes from the return port on the fuel filter and the return from the side of the fuel pump.
If the return ports have been enlarged then there will be more fuel returning than normal which could cause problems.

 

[jaymanek]

Problem now solved

Changed the injectors and guess what, there was no change....

BUTTTT..

the idiot i had working on the car had left a pair of molegrips on the rubber pipe at the tank when he was initially sorting out something else...

This caused pressure to build up and hence return could not return fuel to the tank and hence was causing a diesel fountain under thebonnet...

arrgghhhh.. ive spent hundreds on the new injectors when we didnt even need them..

anyway, all solved, customer happy with his car.. tension relieved!

 

[Mercedes cozy]

Very painfull experience by the look of it.

 

[GazCaff]

I suppose you can take some peace of mind in knowing that you won't need new injectors for a long time now. Tough way to find out though.

 

[jaymanek]

I suppose you can take some peace of mind in knowing that you won't need new injectors for a long time now. Tough way to find out though.

yes well it was a customers car, I had sold it already... well at least she's happy!

 

[Dieselman]

the idiot i had working on the car had left a pair of molegrips on the rubber pipe at the tank when he was initially sorting out something else...

I bet he squealed when you clamped them on his nuts!

I thought you'd checked the return pipe was clear....

 

[Parrot of Doom]

You could get the injectors ultrasonically cleaned, and flog them on Ebay. Just be honest about them

 

[jaymanek]

I bet he squealed when you clamped them on his nuts!

I thought you'd checked the return pipe was clear....

arrgghh, thats really what i felt like doing, but then the guy is just so innocent, he stood there with this sorry look on him...I just couldnt have a go at him....

Well i blew through and i heard bubbles at the other end, thought it was ok, but obviously wasnt...

................

No Injectors were a Swap, could only get them for the price i did if i gave the old ones in...

anyway... lesson learnt... if you want something done... do it yourself!

 

[Dieselman]

arrgghh, thats really what i felt like doing, but then the guy is just so innocent, he stood there with this sorry look on him...I just couldnt have a go at him....

You mean that calf-like vacuity.