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  #1  
Old 02-03-2010, 07:02 PM
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Fuel leak at injector, need nozzle or holder?

I have a significant fuel leak at one injector site. I attached a picture because I'm hoping someone can tell me a bit more about the injector assembly. To me it appears that there is some sort of gasket or seal that is crooked in the center of the injector holder, but I wasn't really aware that there was one from what I've read. One pic is of my leaking injector, and the other pic shows a non-leaking injector's "seal".
All in all, I guess I need to know what I need to replace... I've only seen the nozzle on it's own, which is cheaper, or the entire injector, holder and all, more expensive but would certainly solve the problem.
Does a new nozzle come with the gasket that appears to be damaged on mine?

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Fuel leak at injector, need nozzle or holder?-bad.jpg   Fuel leak at injector, need nozzle or holder?-good.jpg  
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Old 02-03-2010, 07:10 PM
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You first need to determine the source of the leak. It could be the hard line fitting, the return lines, or an internal leak. Internal leaks seldom occur unless the injector was disassembled.
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Old 02-03-2010, 07:27 PM
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It's not the return lines, I assumed it was and replaced them.
This injector has always leaked since I owned the car, so it may have been disassembled.?.
I don't think it's the hard line fitting, but not sure how to be certain??
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  #4  
Old 02-03-2010, 08:28 PM
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Quote:
Originally Posted by anderson82300D View Post
I don't think it's the hard line fitting, but not sure how to be certain??
You might tightening the fitting. Just don't get carried away with the torque.
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  #5  
Old 02-04-2010, 12:36 AM
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One of they ways to be certain where the leak is is to degrease the area with Brake Cleaner and get a strong Flash Light and have someone start the Engine while you watch where the leak is comming from.
Another possible source of a leak is the base of the return line Nipple or if the Return Line Nipple on the Injector has a nick on it. If it is leaking at the base the upper part of the Injector needs to be replaced. But, if that is done it will need to be Pop-tested as that would change the opening pressure of the Injector.

If it is leaking between the Injector Nozzle Nut and the Upper Body you can try removing the Injector and retorquing the Injector Nozzle Nut; and install it again and see if it leaks.
If that does not help the Precision surfaces inside of the Injector need to be lapped flat again and the Injector nut torqued properly.

In the attached pic the Red Arrows point to the precision surfaces. The one with 2 arrows indictes both top and bottem need to be lapped.
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Fuel leak at injector, need nozzle or holder?-mercedes-injector-pic-b.jpg  
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Old 02-04-2010, 12:44 AM
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I have been looking at the pics. If the Injectors have a plastic band around them and have a number on the band NX something they are previously rebuilt Injectors.
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  #7  
Old 02-04-2010, 07:40 AM
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Quote:
Originally Posted by Diesel911 View Post
One of they ways to be certain where the leak is is to degrease the area with Brake Cleaner and get a strong Flash Light and have someone start the Engine while you watch where the leak is comming from.
Another possible source of a leak is the base of the return line Nipple or if the Return Line Nipple on the Injector has a nick on it. If it is leaking at the base the upper part of the Injector needs to be replaced. But, if that is done it will need to be Pop-tested as that would change the opening pressure of the Injector.

If it is leaking between the Injector Nozzle Nut and the Upper Body you can try removing the Injector and retorquing the Injector Nozzle Nut; and install it again and see if it leaks.
If that does not help the Precision surfaces inside of the Injector need to be lapped flat again and the Injector nut torqued properly.

In the attached pic the Red Arrows point to the precision surfaces. The one with 2 arrows indictes both top and bottem need to be lapped.
When retorquing the nut do you first back it off then torque to spec or just put the torque wrench on and tighten it more?
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Old 02-04-2010, 08:52 AM
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That's a rebuilt injector.

The "367" stamp and the black rubber band (not a true seal) are from the shop that did the rebuild.

Diesel 911 is correct. Most of the time, small amounts of dust - even microscopic - cause the leaks. Cleanliness is the key.

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