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Mercedes Benz 320cdi

Cleaning the injectors, getting them out of the engine and the proper way to install them

In my quest to find the problem which causes the black smoke under acceleration I had to look at the injectors as well. So, took the plastic engine cover off and found that at least one injector was leaking. Or had been leaking, it was completely dry in that area but I couldn't take for granted the problem didn't exsist anymore or was solved in the past.

This is what it looked like.

Part 1: getting the injectors out.


From another angle.

Got the first injector out without much effort, You're looking at the hole in the cylinderhead where it lived. All the rubbish that came loose and fell in the shaft has to be removed, I'll come back on how I did that later on in this chapter.

The second one, which obviously leaked (or leaks) I couldn't get out by hand. It was blocked solid in the shaft. So for the time being I went on to remove the other ones. Here you see pictures of the 1st and 3th one. Both were not sealed in the cylinder head, I suspect they have been taken out and put back in without using new copper plates/washers to seal the injectors up.

They are pretty wet.

The others were dry so I didn't take pictures of those. They also looked in pretty good shape.

I got my "Injector removing tool" out, slight detail is: it's made for BMW diesel engines so it doesn't really fit a Mercedes engine.

This is what I had to work with. Luckily most European diesel injectors (which are used in European cars, this might sound dull but I really don't know what the Americans use) are made by Bosch so they have the same threads and what have you. Anyway, being it both German cars they use the same kind of injectors which was to my advantage.

Don't get me wrong, there is an absolute difference between the two, only the mechanical part, in sizes of the threads, is the same. Length may be different and also how the internals are tuned.

To install the tool I had to take the top of the injector apart, it's not difficult but you have to be aware there are very small parts involved. For sure you don't want to loose them! When I say small I mean really small, like less than a millimeter.

Here is an overview of what is in there and the order in which it came out.

Note part number 7, that is one of the very small parts.

The other one is still in the injector, it's a very small ball which you can see sitting in the middle. You really have to look twice not to overlook it. Imagine that bounces through the engine compartment or gets lost in the gravel.

Now we can screw the spindle in the injector and concentrate on how to set the rest up.

It must be pulled absolutely straight up to prevent damage to the cylinder head. That calls for some inventive "tuning"

This is the setup I made, normally when you got an injector puller which is designed for your specific engine you don't have to go through all of this. Normally it will bolt straight on.

I had to put force on it to the limit of what I thought was the maximum anything else could take. It had to come out so I proceded, one very loud bang but it didn't seem to have budged. Somewhat more force then, with a few more loud bangs it finally came loose! Phew!

Here it is! All the carbon buildup prevented it from coming out in a normal way.

Then.... when I removed the extraction tool I realized what caused the first loud bang.

I pushed it right through the valve cover! Bugger!! Be sure I used some other words as well.

After a day's work I got the injectors out.

For the night I covered up all holes to keep moisture and rubbish out. Yes, including the hole in the valve cover.

Last update : Sept 12th, 2017

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