Diesel often has a reputation for ruggedness and reliability, but even the most legendarily bulletproof examples need some TLC now and again. There are small things that you can do yourself to keep your diesel motor in top condition. You can add diesel fuel additives to clear gunk from your engine or top up your car with fresh oil.
You can also change your glow plugs to make your car run better. The best part is, you can quite easily do it all yourself with a couple of tools and a bit of spare time. We’ve put together a comprehensive guide
If you’re a committed diesel fan you may also be wondering what the future holds for diesel now they’re on a downward spiral. We’ve put together a handy guide on what your next car should be powered by.
Glow plug size guide
The standard sizes for car glow plugs are 8mm, 9mm, 10mm, 11mm and 12mm. Check your car’s handbook to find the size your car uses and then find a glow plug removal tool that fits your glow plug.
The best glow plug removal tools
Best for the glow plug wire nut
Pros
- Top-quality
- An essential tool that everyone should own
Cons
- Only useful for one part of glow plug removal
The best glow plug removal tools
Editor’s pick
Pros
- Great value
- Good quality
Cons
- Not the best for jammed glow plugs
Best glow plug removal kit for damaged glow plugs
By allowing you to remove the central contact and drilling the glow plug thread, it can help remove 8mm and 10mm glow plugs. It also comes with a hard case for secure and easy storage.
Pros
- Everything you need to remove glow plugs
Cons
- Expensive
Best simple socket option
Pros
- Great value for money
- Easy to use
Cons
- Only fits 10mm and 12mm glow plugs
- No good if your glow plugs are damaged
Best glow plugs, spark plugs and air sensor kit in one
Pros
- Do more than just glow plugs
- Good value for money
Cons
- Only useful if you own both petrol and diesel vehicles
Best budget glow plug removal tool
Pros
- Good value
Cons
- Won’t be useful in tight engine bays
Best for loosening stubborn glow plugs
Pros
- Very versatile product
Cons
- Won’t actively remove a glow plug for you
Best for easy glow plugs removal
Pros
- Remove stuck glow plugs easily
- Fits every glow plug size
Cons
- Expensive
- Requires an air compressor to work
Best for cleaning glow plug holes
Pros
- Clean your engine out safely
Cons
- Expensive
- Only designed for 10mm glow plugs
How to change glow plugs
1. Disconnect your battery and locate the glow plugs (they’re usually found above the cylinder, but you can check your car’s handbook if you aren’t sure). Remove the glow plug wires from the glow plug. This will be done by removing a small nut that keeps the wire attached to the glow plug. Do this for each glow plug remembering that there will be one glow plug for each cylinder.
2. Remove the glow plug using an appropriate tool (make sure you use the right size). If you find them to be overly stubborn then you might need to purchase some lubricant or a kit designed to remove damaged glow plugs.
3. Once all of your glow plugs are out you’ll be wanting to clean away any carbon deposits. Using a glow plug reamer or aperture cleaner, clean the glow plug hole. Also clean the electrical contact point, removing any dirt that has built up.
4. Using the same tool you used to remove the old glow plugs, install the new glow plugs being careful not to over-tighten them (this will make them harder to remove next time).
5. Reconnect the glow plug wires and the nut using a wrench. Then all you need to do is reconnect your battery.
What do I do if my glow plugs are stuck?
If you have to use a bicep-building level of force to remove a glow plug they might either be damaged or have been in the car for too long.
If the car has been idle for an extended period then in most instances it should simply be a case of spraying some lubricant on your glow plugs. They should then be easily removed with a standard glow plug removal tool.
If they’re broken, on the other hand, then it can be a tricky affair to remove them. It is incredibly easy for a glow plug to become damaged when being installed. Over-torquing them can strip the threads, effectively locking the glow plug in place. Thankfully, there are glow plug removal kits that will help get these glow plugs out without damaging your engine.
Ryan Gilmore is the Deputy Autos and Tools Editor for Parkers, specialising in car cleaning and hand tools. A veteran car cleaner; if it details, waxes or washes he’ll be on hand to make sure it’s worth your money.
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