Installing TDI nozzles (for all 1996-2003 Volkswagen TDI)
difficulty: 2/5
back to 1000q: TDI faq and "how to" index
Introduction
Due to mileage and use, the tip of the fuel injector (the nozzle) will wear out and requires replacement to restore the injector's spray pattern to like new condition. The benefits are both more power and economy. If you think there is a problem due to bad fuel or buildup, you can try running a can of diesel purge through the fuel system. Buildup due to low quality fuel and normal wear will disturb the spray pattern and cause uneven combustion and temperatures. If the problem is wear, the only solution is nozzle replacement. You can also replace the nozzles with larger nozzles with a larger opening to make more power (and possibly more smoke) by injecting more fuel. It's unlikely for damage to occur from only worn OEM nozzles, replacing the nozzles will restore your lost fuel economy, power, make less smoke, and give the car a smoother idle. For more information on nozzle selection and technical details, see 1000q: nozzle selection FAQ and 1000q: basic power modifications.
Note that although this is an easy job, cleanliness is extremely important! The nozzle holes are very small and particles can damage and clog the injectors. Below is a slightly larger than life size picture of an old nozzle next to a caliper. The entire nozzle tip is less than 4mm and below is an enlargement of a new nozzle tip with a red arrow pointing to the orifice measuring .184 millimeters (mm). You want the injector internals and area around the injector holes to be very clean. This is an easy job, but please follow the directions below! Counterholding is suggested on some parts (like the fuel hard lines) because not counterholding could result in damage! The injector holding forks have been known to break due to overtorquing as well, as make sure you have a torque wrench. For more basic mechanic's tips, see 1000q: basic mechanic's tips.
Parts
10, 14, 13, 15mm wrenches and sockets.
17mm open faced wrench or 17mm flare nut wrench or VW special
tool #3035
torque wrench
brake cleaner spray
PB Blaster
lots of paper towels
vise
pliers
screwdriver
slide hammer to remove the injector (Optional) available from metalnerd
tools (halfway down the page) or you can make your own (see below)
vacuum cleaner (Optional)
new nozzles (4 total) available from : TDIparts.com
,
kermaTDI.com, JSperformance
(Canada)
new copper injector washers VW# 046 130 219 A (4
total, included with most nozzle sales but always make sure)
Procedure
Summary: Remove the glow plug harness, move the fuel lines to
the side, and unbolt the injector holders. Pull out the injectors, remove
the old nozzles, put the new nozzles on, replace as necessary.
Detailed procedure: First let the engine cool down so that is not hot to the touch and park/secure the car. Make sure the car is secure and off before doing anything else. Make sure there is adequate ventilation because some diesel fuel and vapors will be leaked and observe all safety practices cautioned in your factory service manual when working on the engine. Keep all sources of ignition away from spilled fuel and/or vapors and evacuate any fumes that may occur.
Open the hood and remove the top plastic engine cover (3 x 10mm nuts).
Cleanliness is extremely important in this job! Put on rubber or vinyl gloves to protect your hands against the fuel. Once the engine is cool, wipe down any oil or dirt away from the front of the cylinder head, fuel injectors, and glow plugs. Then wad paper towels around the base to collect excess fluid and spray the metal head around the fuel injectors and glow plugs with cleaner. Also clean the flare nuts at the end of the fuel lines. Clean it again. Repeat as necessary. You can also use a vacuum cleaner to help clean the area but I find that carb cleaner is better at loosening stuck particles.
The fuel injector metal pressure lines will loosen much more easily if you spray them with PB Blaster, liquid wrench, or a similar penetrating lubricant. A few drops around the threads of the injector pump union fitting will help prevent pulling the unions out and free up the seized lines.
Remove the black glow plug harness (outlined in red below). Each of the 4 plugs should pull
straight off
easily. Place to the side and clean as necessary.
Use a screwdriver to remove the black plastic clips (outlined in green above) holding the pairs of metal fuel lines together. Some cars have a metal clip, a screwdriver will also work here (see 2 pictures below). Removing this clip will make it easier to move the fuel lines out of the way later. Wad some paper towels around the fuel lines to catch any fuel - you don't want diesel leaking onto the coolant hoses.
You now want to remove the fuel pressure lines from the injector tops. If
you are really concerned about dust you can tape a power towel over the fuel
line ends.
Note: you
probably don't have to counterhold the injector body during fuel line removal
since the injectors will be frozen with buildup but it is suggested to counterhold them for reinstallation or if the injectors are loose. To
counterhold, use a 15mm open wrench against the flat part of the injector body
to prevent movement while you
use a 17mm
wrench to remove the nut at the fuel line. The tightening torque is
only 15 ft-lbs but for some reason, the forks on the injector holding bracket
have broken with only a little excess force. It's
tempting to not counterhold but it couldn't hurt.
The forks can also break when it's 13mm bolt is torqued to greater than 15
ft-lbs, so take note for reinstallation! Remember that a torque wrench
could be calibrated too low so don't try to add more force than
recommended. If it's too loose and leaking it will be obvious because fuel
will spray out.
Now loosen the fuel lines at the lines at the injection pump, just enough to swivel the fuel hard lines out of the way as necessary. I suggest using a 14mm wrench to counterhold the union at the lines at the injection pump end (so the union at the injection pump doesn't spin in the pump).
Also note that the moved fuel lines may interfere with the hood, so avoid closing the hood if there is a clearance issue.
You should now have plenty of room to remove the needle lift sensor's wire coming from
injector #3. It's the only injector with the wire coming out of the
top. Pinch in the metal or plastic clip at the plug (circled in red below) and carefully wiggle the plug off.
Note: pictured below is a mk3 engine. Bottom picture is a mk4 engine, they are both very similar
except the plug is in a slightly different location and different connector.
Remove the 4 injector holders (the metal fork holding the injector) and place to the side. There is 1
conical washer
on each injector holder and they are each held by 1 x 13mm bolt (circled in red
below). Note that in the below picture I removed a glow plug to do a
compression test and hadn't yet cleaned the other spots or removed the fuel
lines.
You should now have easier access to the area around the injectors, clean it again.
Injector removal tips
The injectors can now be pulled straight out since there are no threads, there is nothing but buildup holding them in place. Note that most people find that the injectors will wiggle out, some people find that they are completely frozen in place. Here are a few tips. You can either buy, rent, or make your own slide hammer to carefully knock them out. I will first mention what NOT to do because it's very important that you not mess up the injectors. Lastly, some people like to put some drops of PB Blaster penetrating lubricant around each injector hole a few hours before you start the project. This will give the PB Blaster time to penetrate the area and should make it slightly easier to remove the injectors by breaking up some of the buildup. Also, if you leave the injectors out of the car and dry for more than 24 hours, it is suggested to keep them immersed in diesel. Injectors have been known to seize when left for a week dry and cause problems.
Wrench method: To remove, first try using a 15mm open faced wrench on the flat part of the metal injector body to wiggle them back and forth. Do NOT pull on the fuel lines or nipples with anything more than a gentle touch. I had to wiggle them back and forth about 30-40 times before they could be easily removed. See the picture below or at the top of the page to see the exploded injector assembly. Try to rotate it clockwise first or wiggle it back and forth so that it doesn't loosen the retaining nut before you loosen the whole assembly. If this happens, the injector internals will pop out and the injectors will not be happy.
Slide hammer method: If they are truly seized you can use a slide hammer to pull them out. A slide hammer is a weighted rod that lets you apply force on the injector along the axis of the slide hammer. They are available from metalnerd tools (halfway down the page) or you can make your own. To make your own, find or rent a slide hammer and attach the end to the injector threads. The threads are 14mm x 1.5mm pitch. Note that some hardware coupling nuts are 2mm pitch, so make sure to check. A 3lb weight should work, a 5lb weight may be needed for extreme cases.
Once you get the injectors out:
I suggest removing all 4 injectors as an assembly with the fuel lines and placing them on a fresh and clean paper towel.
Below is a picture of the head after injector removal. Note that the
hole is not threaded. You can see buildup in the #2 injector seating
surface. Clean the area around the injector holes and seating
surfaces. This is very important, because excess dirt can cause a compression leak if not
cleaned! I suggest using a soft swab moistened with carb cleaner to wet the
area first. If you use a q-tip, tie a string around the end because it's
small enough to fall into the hole and cause a bad day. Do not spray fluid directly on the hole instead
of on the q-tip first to avoid getting fluid inside the injector hole since it leads to
the cylinder and could cause hydrolock. This is a type of serious engine
damage resulting from letting too much non-compressible liquid inside the
cylinder. Carb cleaner should evaporate if it gets into the hole but it's not instant. I do not suggest using metal objects to clean the area since
this can cause a scratch and leak. It's tempting to use a pick or
screwdriver but I would avoid since the head is aluminum, a soft metal. Also do not use compressed air since
this will blow particles all over the freshly cleaned surfaces and onto the
exposed fuel lines. A vacuum cleaner works well here as well. If a
small piece of built up soot falls into the hole I wouldn't be worried because
it should burn up but still take care to avoid this as much as possible.
The sealing washer will be stuck on to the injector with soot. I suggest using pliers since a 1/4 turn can easily remove it by breaking the buildup seal. A very light pressure can remove it and don't go near the retaining nut's sealing surface to avoid scratching it (marked with a red line below). Don't use a screwdriver or pick to remove the washer because you are asking for a scratch! Clean the exterior of the injector as much as possible.
Note: If the copper washer is not there, it's probably stuck to the
cylinder head! Remove as necessary to prevent any compression leaks.
Use a vise to hold the flat part of the injector body - put a paper towel around the base in case fuel leaks out. (It also keeps the injector clean since my vise was dirty). If you are thinking of just holding it with pliers you are asking for a dropped/dirty/damaged nozzle. All four of my injectors also needed a breaker bar to loosen them, so some sort of vise is a must here!
Use a 15mm deep socket or wrench to loosen the retaining nut/cap. Because it will be so tight, I recommend using a 6 point deep socket/wrench instead of a 12 point socket/wrench or an open faced wrench. This will minimize the chances of the wrench slipping and scratching the retaining nut. Remember that a scratch on the sealing surfaces can cause a compression leak! See 1000q: mechanic's tips for more useful tips.
Remove the retaining nut/cap and clean the inside and outside of
the nut/cap thoroughly. Also clean the outside of the injector body. Avoid turning it
upside down since the metal bushing can fall out. There is a large metal disk with a
bushing in the center. This can easily blow away if you wipe or use
compressed air, so be careful! If it lifts up, it will only seat 1 way,
and the nozzle will also only seat 1 way due to the offset pins.
Repeat for all 4 injectors.
Put on the new nozzles, taking care not to touch the tip with anything that will leave a lot of lint or could scratch the metal. Take care not to drop the tip or hit it against anything. Again, note that the nozzle will only fit 1 way, the 2 pins on the injector are offset so that the 3rd hole of the nozzle aligns with the 3rd hole on the injector body. Also don't try to disassemble the nozzle or injector body - they're not toys and you are better off keeping them clean and intact!
When you slip the retaining nut on, go slow to avoid banging the tip. There is a preloaded spring inside so the nozzle will not be completely seated but when you tighten the nut it will seat and some diesel fuel may come out the fuel nipples at the bottom. Note: there is no torque setting, 33 ft-lbs has been mentioned but the correct way to tighten the retaining nut is to turn until wrench tight, then turn another 30 degrees. This should be be than 33 ft-lbs anyways. Undertorquing the retaining nut/cap causes leaks!
You can drop the sealing washer into the injector hole and carefully center it with a thin screwdriver or use a very thin touch of grease to hold the washer on the bottom of the retaining nut as you lower it in. Make sure that the copper washer is fully seated, aftermarket washers have been known to not fully seat and cause compression leaks. Carefully slip the injectors in, replace the injector holders, bolt, and washer. CAUTION - the conical washer for the 13mm bolt is directional! The curved side points down. If you put the curved side up, it will crack the washer.
Remember, counterhold the injector body with a 15mm wrench while you tighten the fuel lines because the injector holding forks are weak and have been known to crack!
Replace all 4 fuel lines, 3rd injector needle lift sensor plug, and glow plug harness.
Torque settings:
Starting the car
You are now ready to start the car. It should only take a few cranks for the engine to start. Try to crank for no longer than 5 seconds followed by at least 30 seconds of rest. As long as you did not empty the fuel filter or injection pump, there will still be some fuel in the system and the car should start with a little cranking.
Check for any fuel leaks or odors. Inspect the area around the base of the injectors for leaks or bubbles. Also try cleaning the area around the fuel lines that you loosened so that you can see any wet areas that would indicate a leak.
You may want to adjust fueling through injection quantity adaptation, see 1000q: nozzle FAQ and selection for more details.
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