Leaking Fuel Rail Nut (pics) - N55 35i

[Hop74]

So I think i pretty much know the answer to this but just venting/asking on here first.

I recently replaced my valve cover and changed a spark plug and coil in cyclinder 6 due to a weird hole i found in the spark plug housing wall.

When i put everything back together, I went to start the car and noticed i was leaking fuel from cylinder 3 right where the rail line connects to the injector. So i figured I had a bad injector. I'm at around 95k miles so might as well change them all. Got them all changed and now cylinder 3 is still leaking at the same spot... where rail meets injector.

I have tried tightening it. Leak. I figured maybe it was too tight so loosened it. Leak. Tried to clean the inside of the nut to see if any debris was in there. LEAK.

So naturally, i start looking at fuel rail prices (because the smaller lines on the rail going to each injector seem to be all one damn piece now unlike the N54) and they are around $650. 🤬

I've already done a shit ton of maintainance on the car this past month so would like to avoid burning that type of money without asking if anyone has had any similar issues like this.

If you look at the T-connector, it looks pretty filthy but I dont think its dirt. I tried to clean it and it wouldnt come off. Seems like its evidence of a fuel leak that has been happening for a while. Car starts up fine. No misfires when revving but dont wanna drive it of course.

I feel like its a $650 answer so dont be afraid to keep it real, but hopeful for any tricks or ideas from this amazing forum!

[Tomcat_F15_STL]

Yeah that sucks. The tubing may actually be cracked.

Look for a used part on eBay, friend.

[Hop74]

Ordered a used fuel rail from ebay as suggested for less than $90. So i feel better for now. I forget there are good quality things on there.

[Tomcat_F15_STL]

Keep us posted. I’m certain you know, but finger tighten all first. Then a crowsfoot adapter set at ninety degrees on your small torque wrench to tighten the fittings.


BMW N55 Valve Cover Replacement Torque Specs:
All 24 valve cover bolts: 8.5Nm / 6 lb-ft
Small fuel lines: 23Nm / 17 lb-ft
Large fuel line: 30Nm / 22 lb-ft
Fuel rail mounting bolts: 13Nm / 10 lb-ft
Strut bar center: 100Nm / 74 lb-ft
Strut bar to shock tower: 34Nm / 25 lb-ft
Intake manifold nuts and bolts: 15Nm / 11 lb-ft

[Hop74]

Originally Posted by Tomcat_F15_STL

Keep us posted. I’m certain you know, but finger tighten all first. Then a crowsfoot adapter set at ninety degrees on your small torque wrench to tighten the fittings.


BMW N55 Valve Cover Replacement Torque Specs:
All 24 valve cover bolts: 8.5Nm / 6 lb-ft
Small fuel lines: 23Nm / 17 lb-ft
Large fuel line: 30Nm / 22 lb-ft
Fuel rail mounting bolts: 13Nm / 10 lb-ft
Strut bar center: 100Nm / 74 lb-ft
Strut bar to shock tower: 34Nm / 25 lb-ft
Intake manifold nuts and bolts: 15Nm / 11 lb-ft

Didnt know the torque specs for the rail. Good info. Thank you!

[Tomcat_F15_STL]

You’re welcome. One last thought - using a magnifier and light i would fully inspect the threads and seat of the injector before fitting the new fuel line.

.. looking forward to the update!

[Hop74]

Update: All is well! Got the used rail off ebay and no leaks! When i inspected the old rail, i couldn't see anything that looked like a crack with the naked eye. Also didnt see any difference in how the rail sat or how the nut connected to the injector.

But whatever was causing the leak must have been extremely tiny. Just glad its fixed.

Below are pics of the old rail just for kicks. Specificlly, line #3 nut where fuel was leaking from the top of the nut as well as the side.

Thanks for the help again!

[Tomcat_F15_STL]

Great news!