I decided to replace my original fuel injectors now that my 190E was about to hit 140,000 miles.
It is not a difficult job. It can be done in about 1.5 hours.
The parts required:
New OEM injectors (4)
New OEM injector seals (4)
The tools required:
12mm wrench - injector
14mm wrench - injector fuel line
10mm socket - air cleaner housing
13mm socket - injector plate
WD-40 spray - for helping in getting the seals onto the new injectors
Remove the air cleaner housing (3 nuts, two on top one on the side by the throttle cable). (Disconnect the breather hose, air intake duct, and air-temperature sensor from the front of the air cleaner housing first).
Since the fuel system is under pressure, we need to relieve the pressure. Remove the plastic panel located behind the battery. Behind this panel are several components, including the Fuel Pump Relay.
Remove the fuel pump relay. Then crank the engine for about 5-10 seconds, and this will relieve the fuel pressure in the system. Using this technique, I didn't spill a single drop of fuel during this job.
Here's what the fuel pump relay looks like:
Examine the injector hold-down plate and fuel rail nuts. This is what we have to remove now:
I would recommend replacing the breather hoses at this time. If they are old, they may break apart as you handle them while doing this job:
Here's a view of the front injectors:
Using the 14mm open-end wrench, remove the fuel-rail nuts (hold the injector at the same time with the 12mm wrench):
Now remove the plate nut using a 13mm socket and extension:
Here's a picture of the hold-down plate:
Remove the old injectors from the cylinder head ports and clean the port area in preparation for the new injectors. Here's the old injectors compared to a nice new shiny new one:
Now install the new injector seals onto the injectors. It's a real tight fit, so spray some WD-40 onto the seal and twist it onto the injector. NOTE: PLEASE BE CAREFUL TO NOT ALLOW ANY DIRT TO GET
NEAR THE TIPS OF THE NEW INJECTORS WHEN HANDLING THEM.
Here's how the seal looks when fully seated on the injector:
Here we are ready to insert the new injectors, after that the plate goes on and then the fuel rail nuts are tightened onto the injector's threaded shaft.
Slip the new injectors with seals into the cylinder head ports. NOTE: PLEASE BE VERY CAREFUL NOT TO LET ANYTHING FALL INTO THE CYLINDERS THROUGH THE INJECTOR PORTS WHILE THEY ARE OPEN..
Here's an injector inserted:
Install the hold-down plates and tighten them with the 13mm socket and extension:
Using the 14mm open-end wrench, tighten the fuel rails, while holding the injectors with the 12mm open-end wrench:
To complete the job:
- Reinstall the fuel pump relay.
- Replace the panel behind the battery.
- Reinstall any breather hoses removed.
- Reconnect the cold-start valve electrical connector if removed.
- Reinstall the air cleaner along with the breather hose, air intake duct and air-temperature sensor.
Now start the car (it may take an attempt or two as the fuel pressure builds up to normal again) and then check for leaks.
