Glow plug replacement is a fairly common repair on diesel engines. Glow plugs inevitably wear out over time, and it can be a fairly easy remove-and-replace procedure. However, this repair requires a bit of caution, as sometimes glow plugs seize and become difficult to remove. If it happens to you, don’t apply too much force, as broken-off glow plugs are expensive to fix. I’ve replaced 3 glow plugs so far, all have come out fairly easily. Cost per glow plug is about $20. This can be done in 15-20 minutes with some practice – sure beats the $150-300 at the dealership.
Diagnosis
A worn out glow plug will cause a check engine light. In addition to the CEL, you will likely see the glow plug coil light on your dash after the engine turns on – it turns off after 10 seconds or so. Check the error code, it will be a number between P0671 and P0676, where the last digit indicates the glow plug number (i.e. P0675 is for glow plug in cylinder #5). I have read that engine codes for the older T1N (2002-2006) Sprinter are unreliable, but this isn’t a problem for the NCV3.
Parts
- Bosch glow plug (note that the old Sprinter uses a different glow plug)
- Anti-seize compound
- PB Blaster or other penetrating lubricant
Tools
- Socket wrench (8mm and 10mm)
- Torx bits
- Pliers
- Optional but recommended: glow plug connector pliers
Procedure
Before you begin, I have found that removing glow plugs is much easier with a warm (not hot) engine. After driving, let the engine sit before working on it for 30-45 mins before you get started. It can be difficult to remove glow plugs when the engine is cold.
Follow the instructions to remove the air filter housing as well as the engine heat shield from this article. You should be able to see the top of the engine and the fuel filter now. You will also be able to see the plastic glow plug connectors that sit on top of the glow plugs. The cylinders on the Sprinter are numbered from #1-6 in the following order (1, 2, 3 are passenger side; 4, 5, 6 are driver side):
For reference, the following picture shows the general location of the glow plugs, the fuel filter and the turbo resonator. You may have to remove the turbo resonator to access some of the glow plugs (I believe only for #5 and 6).
If you need to remove the turbo resonator (again, only if you can’t reach the glow plugs otherwise, i.e. #5 or 6), remove the 4 bolts using a socket wrench as indicated in the picture below. Note the bolt labeled #4 is only visible if you look from the driver side. Be careful not to drop these bolts, it will be a pain to get them out of the engine compartment. With the 4 bolts removed, locate the smaller Torx screw that holds the turbo resonator in place with the down tube on the driver side. Remove the screw and metal bracket.
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- 4 bolts
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- screw and bracket
Now the fun part. Using a combination of regular pliers, glow plug connector pliers, and your fingers, lift the glow plug connector up and off the glow plug. I have found this to be a bit frustrating, but maybe I just lack the motor skills required for the task. try to grab the connector at its lower, rounded part and lift up. Sounds so easy when you just write about it.
With the connector lifted off, you should see the metal tip of the old glow plug. Use an 8mm deep socket with an extension and try to loosen it gently. If it doesn’t move, apply some PB Blaster and wait a few minutes, it should come off most of the time. If it still can’t be loosened, apply some more PB Blaster and let it sit for a bit longer. Don’t apply too much force. If it just won’t come undone, put all the parts back in place, drive the Sprinter for a day and try again then.
With the glow plug out compare old vs. new:
Before inserting the new glow plug, apply just a little bit of anti-seize compound to the threads (make sure there’s no compound on any other part of the glow plug). This will make it easier to remove next time. Now all you have to do is reverse all the steps above to put it all back together. Insert the new glow plug, tighten with 8mm socket, then reattach the connector. If you removed the turbo resonator, put it back in place (be careful with the rubber o-rings!), attach 4 bolts, 1 metal bracket and 1 torx screw. Put the heat shield and air filter housing back in place.
With everything reassembled, start up the engine. It should show no engine light now (you may have to reset the check engine light manually for it to disappear).