ff wat voor je opgezocht, blijkt een redelijk vaak voorkomend probleem te zijn, hier met tekst en foto's
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So why would you want to replace your injectors then? Well, as the engines get old, the injectors tend to fail and leak. If you pull fault codes out of your computer, it may tell you that you have a faulty or leaking fuel injector. See my article on Reading BMW Fault Codes for more details on how to do this. You may also find that you can see or smell a particular injector leaking. If this is the case, you may not have to replace the injector itself, but may only need to replace the injector o-rings.
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There are three types of injector leaks - it can leak fuel into the manifold from the nozzle, it can leak fuel into the engine compartment from the fuel rail, and it can leak air (vacuum leak) from the manifold. The first leak cannot be fixed at home - you need to have the injector repaired or replaced (I recommend replacement, as it will be pretty old anyways). The fuel rail leak is easy to content with - simply replace the old, fat o-ring that seals the injector to the fuel rail (Figure 15). This should be done anytime the injectors are out of the car.
The third leakage area is a bit of a catch-22. The tip of the injector needs to be removed from the injector. While this seems easy, and indeed it is easy to remove, it is just as easy to damage the tip when you remove it. I have not found a source for these tips, other than purchasing a new injector ($80-$120), so the risk here in replacement is very high. The method that I used to replace one of the seals in the tip seemed to work, but it also did slightly ding and damage the green plastic, fragile tip of the injector. Figure 13 shows this tip.
The method I used was to first remove the old o-ring by cutting it off with a razor blade (Figure 16). Be careful not to damage the green plastic tip when you cut through the o-ring. Then, remove the o-ring with a pic, again taking care with the tip (Figure 17). Finally, to get the new o-ring on, you will need to remove the tip. The best method I figured out for removing the tip was to get a small 8-9mm crescent wrench and apply uniform pressure against the tip (Figure 18). However, this still results in some of the plastic on the tip becoming marred. Pressing up with the wrench using a surprisingly large amount of force will make the tip pop off of the injector. At this point, you can attach the new o-ring and snap the tip back on.
Because of the danger in damaging the tip of the injector, I do not recommend replacing the o-ring behind the tip unless you had a clear manifold leak. I would almost recommend putting some sealant or silicone around the edge of the seal instead of installing a new o-ring. I found it just too easy to damage the green plastic tip. I'm not sure what effects a damaged tip would have on engine performance.
If you are replacing all your injectors (Figure 19), or the o-rings, make sure that you place a very tiny, tiny bit of white lithium grease on the edges that will be pressed into the fuel rail and the manifold. This will aid in the insertion of the injector and the reassembly of the fuel rail. It will also help to prevent the o-ring from pinching, and will guard against tiny leaks as well.
Installation is basically the reverse of removal. You may find it easier to insert the injectors into the manifold first - if you have enough room. Double-check to make sure that all of the fat o-rings are securely seated when you reattach the fuel rail. Don't attach the two top plastic covers just yet - you will want to leave them off so you can check for leaks. When you are ready to fire up the car, have an assistant on hand, in case there is a fuel leak. Have them watch the injectors and the fuel lines to make sure that there are no leaks. If all checks out okay, then button up the top two covers, and you're done!