Sprinter running problem

[BioJoe]

Hi all, and sorry if this has been asked before.

I have an 1999 Sprinter 308D which I bought recently. It had a problem starting on its own but with a little easystart would start straight away. A couple of days ago while driving there was a pop then a lack of power and lots of smoke out the back (sure it is fuel related).

I have changed the air and fuel filter, bled any air that might be in the pipes. It idles really nice but misses when driving (under load).

Any suggestions anyone. I have purchased 2 new injectors and intend replacing each pot with the new injector to see if that makes a difference in the morning.

Joe

 

[Roxie]

If the poor starting is actually extended cranking before it starts. It will probably be an injector, to find the faulty one you need to do a leak off test.
The missfire under load sounds like it could be many things and realy needs to go on a diagnostic computer.(Star) But have a look at the engine wiring harness first they can chaffe through in the inner wing/chassis leg, and on the engine mounting arm if it has not been cable tied up properly.

 

[BioJoe]

Thanks Roxie,

I was under the impression that the leak off test only works on common rail and I think my Sprinter is direct injection. Am I miss informed?

 

[Roxie]

Woops! Should have read the model I suppose.
I think that you have a OM601 engine 4cyl. No turbo or electronics. This engine is indirect injection and starting will depend on the correct function of the glow plugs. (The pre chambers will need to be heated). No real issues with misfires. Possibly sticking Injectors but I would think this would be more evident at idle. Blocked fuel filters could cause issues when trying to accelerate. Dont forget about the pre filter in the side of the filter housing.

 

[BioJoe]

Thanks for the info Roxie.

Just to complicate things - when replacing the very front injector I managed to cross thread it. Is this repairable or do I need to get a new head?

 

[snoopy20]

I did that on mine, if you get the angle right and rotate slowly while pushing down it should get the thread again, even if the top part is knackered.

Sticking injector will be evident on idle and not so at higher RPM's.

I believe this is the same engine as the 250D/300D. If so then the head gasket could well have gone it's a known fault and Merc fixed it with revision #6.

Faulty injector: http://www.youtube.com/watch?v=N8_9e6TqHus

HG failure: http://www.youtube.com/watch?v=BR59hRBBAAY

 

[BioJoe]

Tried getting the injector in at the right angle but no luck. At a standstill the knock is evident at idle then goes when revved. Waiting for a thread doctor to come and have a look.

I assume there is no point in checking the knocking until I get the injector in straight.

Checked the oil and water for obvious signs of head gasket failure and none found.

New air and fuel filter, found the pre filter after the comment from Roxie, thanks.

 

[Roxie]

Does it screw into the the prechamber? I am trying to remember but I think you might get away with a new pre chamber.

 

[BioJoe]

Thanks Roxie,

Thats what the thread doctor thought when I spoke to him on the phone but it looks to me that it goes in the head. Definitely alluminium though.

 

[BioJoe]

After many hours reading forums and searching and a phone call to the local Mercedes Parts Dept I have come the following conclusion.

I have a OM601 engine with prechambers; the prechambers fit through the head; the prechamber has a collar that the injector screws into.

I need to replace the collar! Does this make sense so far and is it difficult?:neutral:

 

[snoopy20]

I did not know it had a collar. I've had the head of mine to do the head gasket and it was a complete bastard.

 

[Roxie]

The collar is splined inside and a special tool goes in like a socket and unscrews it. The glow plug is then removed and a slide hammer screwed into the pre chamber this then pulls the chamber out. If the head has been skimed you will find a shim bellow it to keep the chamber away from the piston.

 

[BioJoe]

I did some research on pre chambers and found the following good links:

http://mercedes.thatchermathias.com/w123CD2/Program/Engine/615/05-117.pdf
gives a diagram and photos of how to remove the collar and pre chamber

http://www.peachparts.com/shopforum...diy-617-9xx-prechamber-tools.html#post1701084
gives details of how to remove the collar and pre chamber with diy tools

I have compared this pictures to mine to find it is different. I dont have the collar with notches in I have a splined sleeve as Roxie mentioned

 

[BioJoe]

Roxie, does that mean the injector screws into the top of the prechamber?

 

[BioJoe]

Came across this link to pre combustion chambers with angled injectors and the splined collar

http://www.w124performance.com/images/tools/prechamber_removal.pdf

Another step closer and a little less fuzzy

 

[BioJoe]

Another good link that explains lots:

http://www.ssangyongclub.co.uk/downloads/mussoservice.pdf

 

[Roxie]

Came across this link to pre combustion chambers with angled injectors and the splined collar

http://www.w124performance.com/images/tools/prechamber_removal.pdf

Another step closer and a little less fuzzy

This one is yours.

 

[BioJoe]

Got the cross threading fixed. Thread Doctor managed to repair it and got the injector back in. The thread is in the top of the prechamber so need to look at replacing them sometime in the future.

Now back to the original problem. Got the van started and it is missing. I will try swapping the injectors with a new one, one at a time, to see if that makes any difference. Any suggestions welcome!

 

[Roxie]

Just find out which cylinder is missing by slackening the injector pipes one by one. Obviously fuel will leak out when you do this so have some rags ready to cover the pipe.

 

[BioJoe]

Cracked the top of each injector and everyone caused the engine to slow. Replaced the injectors one at a time and has not made any difference! Still lots of white smoke coming out the back and although it revs well at a standstill it has no power when driving.

My next thought was it must be the head gasket or a valve? Spoke to a mechanic and he suggested the fuel pump as there is no loss of oil or water.