Glow plug replacement questions

Thanks for your quick reply. I would say that it is not loose at all as it barely clicks. An ohmmeter test implies that the plug is good so I am going to leave it. The main culprit here is the controller.

I will also post in NCV3. Thanks!


Well-known member
...BTW, a defective glow plug can damage a new replacement module-so don't replace a specific single glow plug based on DTC info-then find the problem is still present -then replace the module only to have the undiagnosed defective glow plug destroy your new module. Doktor A
Does that hold true with the newer control modules too? I was hoping to skip the testing and go directly to replacing the control module and then see if that fixes it before replacing any glow plugs.


06 T1N Can
In my mind, the warning is for failed glow plugs that fail shorted.

From my little experience, the glow plugs fail open and do not cause damage to the control module.

However, why take the chance? It is very easy to measure glow plugs for failed shorted or open. If they failed open, then you can do your control module replacement. If they failed shorted, I wouldn't plug in the control module. I would replace all the glow plugs first.


Well-known member
... It is very easy to measure glow plugs for failed shorted or open. ...
I guess I'm just getting impatient and didn't want to have to bother testing them. It looks like there are two tests, using either a fuse or a multi-meter. I'll read up on that.

A friend told me about a decent Sprinter mechanic here in Ventura but I'd almost prefer to try extracting the glow plugs myself, because I can spend a few days getting them loosened up. With about 60,000 miles on our 2006 camper, maybe it would be a good idea to replace them all anyway so that I can put some anti-seize on them. But then, there's also the sage advice to leave well enough alone and only replace what's broken.


Well-known member
...It makes no sense to not change it all out since it's only $50 for five good quality, brand new, glow plugs.
I ordered the kit (5 glow plugs and the control unit) from Europarts-SD, so I'll plan on just changing everything out and keep my fingers crossed that I don't break one. It sounds like it's hard to go wrong if I follow all the advice to go slow and limit the torque as I remove them.

Patrick of M

2005 T1N 2500 (NA spec)
It's the twist as well. Metal has elastic properties, and like elastic if you stretch it too much it breaks. That is why impac drivers work so well, after each hit the tension/stretch is released.


Well-known member
My worry was for nothing. But, if I hadn't been worried enough to gingerly loosen and retighten each plug things might have turned out differently.

Looks like I was making a mountain out of a molehill. My glow plug kit hasn't arrived yet but I got impatient and took a stab at removing the glow plugs. The clips came off easily with a narrow pair of needle-nosed pliers and the first glow plug I tried (#2 seemed to have the best access) came out smoothly. The next one was giving some resistance so I sprayed some PB Blaster and warmed up the engine to 170º. Without waiting for the engine to cool, I removed the remaining four glow plugs without exceeding more than about 15 Nm of torque (guessing).

Ironically, it looks like getting at the bolts that hold down the control module might be tougher than removing the glow plugs. :)


Well-known member

You recently had an engine rebuild didn't you? Did they remove the plugs at that time? Just wondering if they came out relatively easily because they hadn't been in terribly long?


New member
After reading so much about it I finally decided to tackle the glow plugs on my 2003 om 612 2500 with 150k miles. Just wanted to drop an encouraging post to say it is possible without taking everything apart.

I squirted some kroil into the plug wells and let it sit over night then went for a drive and immediately got to work. 1,3, and 5 came out smooth and easy. 2 and 4 required some working back and forth and some wiggling with the needle nose pliers.

My tool of choice was a 3/8 snap on ratchet with a 6 inch wobble extension and an adapter to a 1/4 drive 6 point 10mm socket.

All tools pictures below. Thanks for all the info!


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