Technical Glow Plug replacement 3.0

[nigelvan]

2007 3.0 vehicle here. Now I had problems with the glow plugs before but it always started. Initially it would start a bit sluggish at sub-zero temperatures. I figured out 2 glow plugs were shorted so I disconnected them. This way I have - or I suspect I have - 2 working glow plugs. Starting in colder weather is definitely smoother. But cold starting always has some kind of 'hiccup'.

Now we're planning on spending more time in colder climates in the future (read:Scandinavia) and I wonder if it wouldn't be better to swap out the glow plugs.
I've never done this job and I read it can be hard and when you snap them you're in a world of pain. So I'm looking for advise before tackling this:

• What procedure should I follow? Bosch video tells me: penetrating oil for 30 min, warm engine, use torque wrench to avoid snapping them. But this video is way too shiny, I know better!
• Other people say: soak with penetrating oil (WD-40 is ok?) for 12h, repeat again
• Worst case: what happens when it snaps... how do I get the debris out? I suspect pulling the injector (that will be fun) and vacuum?

 

[nigelvan]

A few months later and I'm ready to tackle this. I've bought 4 new glow plugs and have been soaking the plugs in wd-40 for over a week now. I had to remove the throttle body anyway to get a broken MAP sensor out. It's a bit annoying to put everything back together to drive the engine warm enough but better then snapping hem. I'm especially worried about the most right one, it's quite rusty.

 

[Anthony489]

Hi

I don't envy you tackling this job. The problem seems to be that the glow plug design has got more slender over the years, to the point that the torque needed to snap the injector is less than the torque needed to overcome the corrosion. I'd recommend a dedicated penetrating fluid e.g. Plus-Gas in the UK rather than general purpose lubricant like WD-40. May make a small difference and you need all the help you can get. One recommendation is to try and "feel" for the slightest movement, massaging the plug both clockwise and anticlockwise by a tiny amount to begin with. This will help the penetrating fluid to get in further.

If the worst happens, I'd recommend paying someone who has specialised extraction equipment and knows how to use it. I suspect even main dealers farm out this kind of job to them.

 

[nigelvan]

Thanks for the comforting words . Yes I switched over to CRC MoS2 penetrating fluid after reading WD-40 is not the exact right stuff for this. It's been soaking for a week now while I'm doing other work on the van as well. I was planning on using a torque wrench CW and CCW to 'massage' the plug as you put it.

 

[nigelvan]

So I finally attempted to change them. Lots of penetrant/WD40 + let the engine warm up to soak up some more of the penetrant.
I started with a warm - not hot - engine. I managed to free 3 out of 4. Used a 1/4" T piece and an extended 8mm socket. Lots of wiggling back and for + I used an electric drill (not impact) to loosen it but it didn't have enough torque to actually get it out.
A I expected the first one from the right snapped... No warning, just as I thought I was getting some movement. Maybe I should've bought an impact screwdriver for this job.

Anyway I was counting on one or more of them snapping. Now I need to figure out how to get the tungsten out and get a glow plug removal kit. Or I could just leave it in there and run on 3 glow plugs. With all the water ingress no way of guaranteeing that one won't fail again in no time...

Any thoughts?

 

[spidermania]

I know better!

See post #3.
In America we call it, 'tripping over nickels to only save pennies', others might view it or say you get what you pay for.

 

[Anthony489]

Hi

I suspect three glow plugs will be enough to allow you to start except in extreme conditions, though the cylinder without a working plug may take a few seconds before it begins firing. The main snag is that the glow plug controller "relay" will sense that there is no current flowing to that plug and will throw an error code. This can be worked around by connecting a 1 ohm power resistor in place of the "missing" plug, to fool the controller into thinking that all is well.

 

[nigelvan]

Hi

I suspect three glow plugs will be enough to allow you to start except in extreme conditions, though the cylinder without a working plug may take a few seconds before it begins firing. The main snag is that the glow plug controller "relay" will sense that there is no current flowing to that plug and will throw an error code. This can be worked around by connecting a 1 ohm power resistor in place of the "missing" plug, to fool the controller into thinking that all is well.

Even two. When I looked at it the first time the controller relay shut down the power because of a short in 1 or 2 of the plugs. When I disconnected those I effectively had 2 working plugs, nr 2 and 4. This greatly improved starting in cold weather although I had some misfires in the first few seconds in the other two cilinders. When I checked again now, 3 years later, the 2 working ones had deceased as well.

Now, since none of 3 other plugs were really stuck, or even fauled by carbon (they looked brand new when they came out except for the tip). I think, if I can get rid of the tungsten electrode in the middle (I might have to call a mate who can weld a nut to it so I can snap it off). Drilling it out past the thread might be the best option, plenty of kits available. I'm not ready to call in a professional yet.

Btw, as for your first post, massaging the plug is indeed the way to go. I used an air compressor to blow away the debris around the thread and atomize the penetrant, then re-added penetrant and you can immediatly feel the difference after a minute or so. The last plug just had no chance. The fact that the plug connector itself was completely corroded and disintegrated says enough...