Fuel Injector: Service and Repair
13 53 310 Removing and installing or replacing one fuel injector in fuel injection system (N14)
Special tools required:
WARNING:
Disconnect battery negative terminal (risk of fire due to short-circuiting on removal)
Carry out installation work on fuel system only with coolant temperature below 40°C.
Only perform this repair work on an engine that has cooled down: Risk of burns.
IMPORTANT:
Wear full face guard and protective gloves.
Fuel can emerge spontaneously at high speed when the high pressure line is released.
IMPORTANT:
Adhere to conditions of absolute cleanliness when working on the high-pressure fuel system.
Introduced dirt contamination can cause malfunctions in the system.
- Do not allow any dirt particles or foreign bodies to get into the system.
- Remove all traces of dirt contamination before removing lines or separate components.
- Use only fluff-free cloths.
- Seal all fuel system openings with protective caps or plugs.
IMPORTANT:
Wear safety goggles.
Oil and dirt particles may get into your eyes.
After removing the injectors, clean the injector shafts with compressed air.
Necessary preliminary tasks:
- Remove high-pressure rail
Recycling:
Fuel escapes when fuel lines are detached.
Catch and dispose of escaping fuel.
Observe country-specific waste disposal regulations.
Removal:
Remove hold-down device (1) and discard.
Pull up fuel injector (2) to remove.
Procedure in event of stuck injectors:
NOTE:
The following procedure applies to all injectors.
For purposes of clarity, illustration shows and description refers to the removed engine.
Mount special tool 13 0 231 with lettering "Top" facing upwards.
Mount special tool 13 0 232 .
To secure injector, turn nut (1) by hand until noticeable resistance is felt.
13 0 232Turn nut on special tool several turns until injector has been released from hole.
Remove special tool.
Remove injector.
The fuel injector installation procedure is described separately.
IMPORTANT:
When replacing the injectors, adherence to the following instruction is mandatory.
T13To find the correct new part, the 13-digit cylinder head number must be known.
The number can be found on the cylinder head.
Read and write down the cylinder head number.
There are two versions of the injectors and fastener.
To ensure the correct installation of the injectors/fastening components, the cylinder head number is important.
From MCGU10xxxxxxx:
Cylinder head with injector without Stop Choc.
From MCGU15xxxxxxx:
Cylinder head with injector with Stop Choc.
Injector differences:
- For injectors (1) of the first generation, the connecting tube is rounded. The first part of the encapsulation is made of plastic.
Injector (1) has a compensation element without Stop Choc.
- Injector (2) of the second generation the connection tube is slightly thicker and not rounded. The first part of the encapsulation is made of metal.
Injector (2) has a decoupling element with Stop Choc.
Differences between the compensation elements and decoupling elements:
- 1. Compensation elements with circlip are without Stop Choc
- 2. Decoupling elements without circlip are with Stop Choc
Decoupling elements must be replaced after each dismantling.
Procedure for cylinder head number starting with MCGU10xxxxxxx:
Only injectors (1) of the first generation must be installed with compensation elements (2) without Stop Choc and circlips.
Injectors of the second generation with Stop Choc decoupling elements must not be installed.
Procedure for cylinder head number starting from MCGU15xxxxxxx:
IMPORTANT: When replacing the cylinder head with number MCGU10xxxxxxx with the cylinder head with number MCGU15xxxxxxx, the injectors of the first generation may be reused. For this purpose, they must be converted to Stop Choc decoupling elements.
Both injector versions may be installed into cylinder heads starting with number MCGU15xxxxxxx. To do this, the injectors must be modified to Stop Choc decoupling elements (1).
Injectors (1) of the first generation may only be installed into cylinder heads starting with number MCGU15xxxxxxx, if they were modified to Stop Choc decoupling elements.
Remove circlip (2) from injector (1) and pull off compensation element (3) without Stop Choc.
Install new Stop Choc decoupling element (2) onto injector (1) until a clicking noise is audible.
Injectors (1) of the second generation must only be installed with Stop Choc decoupling elements (2).
When reusing or replacing the injector, Stop Choc decoupling elements must be replaced.
Installation:
Installation note:
- Make sure guide pin (3) of fuel injector (2) is correctly positioned in designated bore hole (4) in cylinder head
- Replace sealing ring (6) and support ring (5), making sure support ring (5) is seated correctly
- Replace hold-down device (1)
- Replace Teflon sealing ring
Replacing Teflon sealing ring:
NOTE: N53 Depiction of engine, procedure for N14 engine identical.
Before replacing Teflon sealing ring (1), make sure hands and work surface are clean and free of oil.
Avoid mechanical contact with injector tip (2).
Remove Teflon sealing ring (1) from injector (2) with special tool 13 0 191.
Use a fluff-free cloth only to remove combustion residues from cylindrical part of injector tip (do not use ultrasound or other tools/agents).
Do not clean injector tip (2).
NOTE: N53 Depiction of engine, procedure for N14 engine identical.
Slide new Teflon sealing ring (1) 13 0 195 onto mounting taper .
NOTE: N53 Depiction of engine, procedure for N14 engine identical.
User fingers and mounting taper 13 0 195 to slide Teflon sealing ring (1) onto injector (2).
NOTE:
- Do not use fingernails to slide on Teflon sealing ring.
- Do not use any lubricants.
- The sealing ring is expanded when slid on.
NOTE: N53 Depiction of engine, procedure for N14 engine identical.
To bring the expanded Teflon sealing ring to its installation dimension, slide three assembly sleeves with decreasing diameters onto the injector.
Slide assembly sleeve (1) with large opening first onto injector (2).
Do not use any lubricating agents.
NOTE: N53 Depiction of engine, procedure for N14 engine identical.
First slide assembly sleeve 13 0 192 (large diameter) onto injector (1).
Then slide assembly sleeve 13 0 193 (medium diameter) onto injector (1).
NOTE: N53 Depiction of engine, procedure for N14 engine identical.
Finally, press injector (1) into assembly sleeve 13 0 194 (small diameter).
Assemble engine.
Check fuel system for tightness.
Check function of DME.