O rings- Mercedes 190 250D 1992

[dizzy lizzy]

Mercedes 190 250D 1992.

The car was working perfectly but O rings needed replacing because dripping diesel. Went to my deisel specialist who said he would have to take the whole injection pump out to do the work. So I bought the 5 O rings from Mercedes and the special socket (33) and decided to change them myself.
I could not get a torque wrench in to tighten them to 26nm so done them up by hand until I could feel they were tight and then gave them half a turn with a wrench.
Now the car won't start. Have I over tightened them or do they still have to be tightened more. It;s not drawing up deisel to the injectors.

Many thanks

 

[spock500]

Are these the O rings on the pipes or the ones on the pump itself?

 

[dizzy lizzy]

Are these the O rings on the pipes or the ones on the pump itself?

The ones on the pump itself. Also changed the washers as well on the 5 valves. The old O rings were perished.

 

[wireman]

You need to crank it without pause until it starts, keep cranking until it runs cleanly without miss fire.

Charge the battery before you do it, it might need a full minute of winding up.

Your having been able to get another half turn surprises me, You might have crushed the copper washers out of existence.
You really should have taken the inlet manifold off and done them to the specified torque, you have been dealing with a very fine, delicate and expensive piece of machinery, respect and mechanical sympathy are a pre-requisite with any fuel injection components.
Hope you didn't over torque the injector pipes as well.

 

[SilverSaloon]

i've done this job.

i hope you didnt disturb or turn anything under the copper seal? ie removed the spine, replaced the oring and refitted? any movement here can cause horrendous problems seen on many forums, mainly in the US.

assuming thats ok, i'd buy a torque wrench (£40~ from halfords probably) and do them up to the correct torque.

you will need to crank for a while until it fires.

crank it whilst attched to a running vehicle via jump leads, or disconnect the glowplug relay until it grumbles and then reconnect. that tip will save the battery power a bit

 

[dizzy lizzy]

i've done this job.

i hope you didnt disturb or turn anything under the copper seal? ie removed the spine, replaced the oring and refitted? any movement here can cause horrendous problems seen on many forums, mainly in the US.

assuming thats ok, i'd buy a torque wrench (£40~ from halfords probably) and do them up to the correct torque.

you will need to crank for a while until it fires.

crank it whilst attched to a running vehicle via jump leads, or disconnect the glowplug relay until it grumbles and then reconnect. that tip will save the battery power a bit

On number 4 cylinder the spine came out and I just put it back in again. Would this cause the problem? or am I not tightening down enough.

 

[wireman]

Follow this link

http://mercedes-190.co.uk/topic/226318/ a big download

Its to the MB USA workshop manual, in its 602 engine section there are full instructions for this job.

The five assemblies you have been playing with are the delivery valves.

 

[brianbrian]

I did fully charge the battery but could not pull fuel up to the injectors, as I did disturb one spine would this stop fuel being drawn up to injectors. Hope this helps

 

[Bolide]

26 NM is not tight at all so I suspect the extra half turn will have squished the washers good & proper. I'd replace them and pay attention to the manual

A 250D should fire right up if it's warm and there is no air in the system. Once there is air in there they are a swine. If the car is a manual, tow it to start it. If it's an auto, jump it from a running car with some BIG jump leads. All other attempts will fail

Nick Froome

Nick Froome

 

[wireman]

Disturbing the "spline" is part of the job, no harm will be done by disturbing them, lift it and the carrier out and clean them in fuel, replace them centrally (by eye) in the hole and place the copper washer on top, the threaded cap centres them properly when its screwed down.

The "spline" is correctly called the delivery valve element.

The copper washer is placed between the lower face of the valve cap recess and the carrier ring, over tightening it and crushing it might destroy the sealing properties of the washer and then it just wont be able to pump the high pressure required to open the injectors.

I have taken a look at all the Bosch info I have about the pump and don't think any damage will be done to the pumps major parts by this error, the load from the threaded valve cap is taken by the outer sleeve of the pump element (down inside the pump) and transferred to the body of the pump, the critical bits will not see any part of this load even if its well and truly excessive.

Above all else work clean when you are inside the pump, like operating theatre clean or better.

Torque settings, Injector pipe 10-20 Nm, delivery valve cover 35 Nm.

 

[brianbrian]

I have had two goes at replacing the five orings and copper washers , as first time I took out one spline to look at it, don,t laugh for got to put it back when i reassembled, car would not start, remembered straight away what I had done, do you think I am not tightening down enough, as when I undone them from the last time the copper washers and orings looked ok. But I did replace with new each time as I bought two packets. Glad to hear I have not done any damage, thank you all for your time on this. Wonder if any one has got away with out using a torque wrench, did try to cheat as did not want to take the inlet manifold off. Hope this helps

 

[brianbrian]

I do have a good torque wrench but could not use it as I needed to take the inlet manifold of so I could get in with it. Will do it properly have learnt a lesson. Thanks guys Hope this helps

 

[brianbrian]

Well I decided to give each valve a 1/4 turn more before taking the inlet manifold of, was out there for 1/2 an hour in the cold. Turned the key and after a few turns she spluttered into life,a few seconds later she was purring over like a new car, No leaks I am a happy boy. Hope this helps