REPLACING BMW DIESEL GLOWPLUGS

Posted on 4 October 2015

However old or new your BMW is, at some point you will get a Glow Plug Failure, like any diesel car your BMW has 4 (or 6 on 6 Cylinder Models) glowplugs which pre-heat the combustion chamber to aid starting on cold mornings, BMW also use an afterglow feature, which allows to glowplugs to run for a few minutes after starting to aid emission levels. What many owners don’t realise is that on cars which have a DPF (Diesel Particulate Filter) fitted, if a glowplug fails, then the DPF system will be unable to regenerate, eventually leading to more expensive problems with the particulate filter so it is wise to replace the glowplugs as soon as the failure is diagnosed. If you are unsure whether you have a glowplug failure then you can read and reset the error codes using our Diagnostic Software Package.

It is also false economy to replace just the Glowplug(s) which have failed, and better to replace the entire set. The logic behind this, is that it takes a lot of time to remove all of the plastic covers and parts which are in the way in order to access the glowplugs, so you may as well replace the entire set, whilst the intake manifold is removed. At the end of the day, the rest of the plugs have been in for just as long as the ones which have failed, and so its only a matter of weeks or months before the rest fail and you have to replace them.

It is important to replace the failed glowplugs with good quality long life Glowplugs and I highly recommend using BERU brand. Packs of Beru Glowplugs can be purchased from the links below

BERU GLOWPLUG SET FOR 2.0 LITRE DIESELS FROM 2001

BERU GLOWPLUG SET FOR 3.0 LITRE DIESELS FROM 2001

The biggest problem with removing the Glow Plugs on any diesel car, is finding that the glowplugs have seized in the head, and you end up snapping them, which will then either require the head to be removed or a specialist company to remove the broken plug in situ. Although, thanks to such companies offering these services, snapping a glowplug is not as expensive as it once was, it is probably best to be avoided!.

Glowplugs often end up seized in the head due to either carbon build up, or corrosion between two different types of metal (Glowplug body and Cylinder Head) therefore, its wise to exercise great care in removing them, and soaking them overnight in one of many chemicals suggested below, is likely to make them easier to remove the following day.

When removing my Glowplugs, I always assume that they will be stuck in the head. One of the best ways of loosening the corrosive bond is to soak the Glowplug overnight, one of the best oils to use is called Kano Kroil, this oil ‘creeps’ down the glowplug threads and works on the carbon / corrosion build up making them far easier to remove in the morning. If Kano Kroil is not available, then as an alternative I would also recommend soaking in a mixture of 50 / 50 ATF Fluid and Acetone or 50 / 50 Coke and Vinegar

Even after the plugs have been left to soak overnight, it is important to work slowly and steadily on each glowplug, as too much torque on the ratchet will probably end up snapping them. Start by tightening the plug first of all to try and break any corrosive seal on the thread and then gently apply steady pressure to undo. Even if the Glowplug begins to undo, take it steady and work the glowplug thread backwards and forwards, backing off immediately if any resistance is felt whilst undoing.

When the Glowplug begins to loosen I apply Brunox Turbo Spray down into the thread giving a good spray every turn as the plug is loosened and if any still feel tight whilst undoing then I soak them for an hour in Kroil again and go and have a coffee, patience is the key here as being impatient can end up with you waiting for hours or days for a specialist company to come and remove any snapped plug but i’ve not yet found any BMW Glowplug which has defeated the combination of Kano Kroil and Brunox Turbo and a bit of time and patience its just a matter and working the glowplug forwards and back, whilst spraying in the penetrating oil or soaking for a bit longer.

In short WD-40 should be avoided as it is not the best penetrating fluid out there, and will certainly not be of much use for stuck glowplugs!, but if the fluids that I recommend are not available, then you can also use the following products for pre-soaking and during removal.

A 50 / 50 mix of Coke and Vinegar (These can also be used on their own and don’t have to be mixed)

Mineral ATF Fluid and Acetone in a 50 / 50 mix

PlusGas Spray

Brunox Turbo

Liquid Wrench Penetrating Spray

BG In-Force Penetrating Spray.

 

When replacing the glowplugs, it is worth putting some High Temperature Ceramic Grease on the threads to prevent them from sticking in the head, should they need to be removed in the future. Conventional copper grease SHOULD NOT be used in this application.

Once the Glowplugs have been replaced, you will need to clear the fault code, using Diagnostic Software.

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