Hello,
Other than spraying liberally and soaking with Plus Gas for a couple of weeks, does anyone have any other tips or tricks to releasing two potentially stuck glow plugs in a ?96 C220 diesel.
Regards
Ellis
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I had exactly this problem with an auction-bought Merc CDI - its very common. Lots of Plus Gas and nerves of steel eventually got mine out. Don't snap it otherwise the head has to come off.
Won't be buying one again!
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Before trying to release the glow plugs ,get the engine as hot as possible.
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It would be a good idea if owners of diesel engines ensured that the glowplugs are removed and the threads (not the taper seat) coated with copper loaded anti-seize compound, repeated every 2 years. The best glowplugs (Beru) last so long nowadays that it might be some time before they have to come out. Don't overtighten on refitting, otherwise the plug body will distort, as its hollow.
Having done this on the Peugeot 106D I look after (first plug failed at 95k miles), I was smugly able to change an open-circuit plug in 5 minutes.
659.
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And if you should lose one(or more)of the nuts while doing it,suitable nuts are sold at Halfords.
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According to my contact at the local Merc dealers they use a torque wrench ("backwards") when trying to undo these; if the torque exceeds a certain amount and the plug is not shifting then they leave it.
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It's good to see that MB are ensuring trouble free cold starting from their customers' diesels by pursuing this kind of policy.
There might be a grain of sense in paying dealer's prices for servicing if they applied preventative maintenance gained from their operating experience of the models of their franchise. All vehicles have design shortcomings and wrinkles, and it can make a profound difference to the long term operating costs of a vehicle if problems such as this are addressed during routine maintenance.
Most dealers, especially those representing the more expensive Teutonic marques, are too stuck up to admit to any weaknesses at all - long live this Forum!
659.
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I agree,well said that man!
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a torque wrench ("backwards") when trying to undo these; if the torque exceeds a certain amount and the plug is not shifting then they leave it.
Thanks for the comments, Aprilia, do you happen to know the torque setting that your contact uses, might prevent an unfortunate incident, thanks
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Is it wise on a job like this where things might be tight to try and "tighten" the plug just a touch to "crack" the seal or would that do me no favours at all?
Thanks
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if you can get a blow lamp in safely warm around the plug not the plug itself, then see if it will crack off, then work it back and forth till it comes out, then i would do as somebody has mentioned put some cooper slip on those threads.
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I have found building a small reservoir round the offending nut/plug with plasticine and filling with vinegar and leaving for 2-3 days does the trick. The acetic acid in vinegar tends to dissolve rust. Any oil tends to protect the rust:-(.
On all cars I use copperease on all threads especially glow plugs or even the threads (not the seating valve!) - and very sparingly - of bleed nipples. (notorious for rusting and easy to break).
madf
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I have shifted glowplugs in the past by building a reservoir of silicone sealer around the plug to take commercially available dismantling fluid. The advantage of using a silicone based sealer is that it will withstand engine heat, enabling you to operate when the alloy head (which expands more than the steel glowplug body) is hot. After a few heat cycles using engine heat with a pool of liquid around the plug, mask the surrounding head with cloth, and spray the plug body with electrical freezer spray - use about half a tin.
If at all possible, use a "T" configuration spanner handle on the plug to avoid a bending moment and try to jerk it free, anticlockwise. Further tightening on a taper seat is no use and in this situation, one's own judgement is far better than a contrived torque figure. The compliance caused by the use of a torque wrench would limit the effectiveness of jerking it free.
Best of luck - the latest Beru plugs (no connections, I used to work for the opposition) have stainless bodies, which cause fewer difficulties.
659.
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Isn't this madness. MB know of this problem. They must be able to have a commercially designed system to coat copper paste on the plugs, or insist that Bosch or Beru do it before assembly. Once the problem started they should have got their mechanics to do the job at the 1 or 2 year service when easier extraction would have been possible.
Apart from MBs arragance at leaving the problem, what confidence does it give owners to know they are happily waiting for you to hit a £2,000+ problem on your own for the want of 5p's worth of grease.
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I'm afraid that now MB is run by accountants and not by engineers, they just don't care. I used to admire greatly the quality of their engineering; now, the more I see of it, the less I like. The steering column in a RHD A class must be the pinnacle of their recent design "expertise".
659.
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OK, I think I have the solution for you...Just been to local Diesel specialist to buy a part and had a chat with him about stuck glow plugs.
There have been so many problems with stuck glow plugs (the 'long' type used on most CR Diesels) that a new tool has been developed especially to remove them. Basically its a type of air wrench that **vibrates**. The vibration loosens the corrosion seal and the wrench applies a stready torque to undo the plug. There is clutch incorporated so that not too much torque is applied.
The tool costs about £1000. I suggest you ring around local Diesel specialists to find out if anyone has one. ECP are one of the distributors, so if all else fails give your local branch a call and ask who they've sold one to.
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Sounds like a hammer drill attached to a socket...
madf
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My thoughts too. Even a decent batery drill in "screwdriver" mode with a suitable socket adaptor might do, if it has a bi-directional overtorque clutch, as some do.
659.
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well I would take your (659's) idea and modify it as :
1. run engine to warmed up fully.
2. silicone shield as 659
3. apply pipe ccolant spray via a directional tube (as on WD40 cans) to glowplug only.
Th resultant contraction of the glowplug in a heated block should allow the joint head/plug to expand and allow the whole thing to move.
Then apply a hammer drill with socket on a low torque setting.
I would have thought that stood a very good chance of cracking the rust corrosion seal.
madf
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Thanks for the responses, I'll read and digest and when the job is attempted will report back.
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