I've just had an oil and filter change on my Citroen Berlingo (5 years old, 62,000 miles) at a main dealer.
As I was waiting, a gent came out of the workshop with the sump plug to show me that the thread was damaged. I'm not sure, but I think that means that the thread on the sump itself would also be damaged. He told me he was going to try to get it in, but he was not certain it would work - and if it didn't, the car would need a new sump - which he didn't have in stock. Anyway, he got it in, but told me next time the oil is changed, the car will need a new sump.
How common is this sort of damage? I was surprised to hear of it on a fairly new vehicle.
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Two developments have conspired to make this problem more common.
Firstly, engine sumps are generally now aluminium castings as opposed to steel pressings in order to attenuate noise, especially on diesel engines.
Secondly, the quality of main dealer servicing personnel has deteriorated. This means that the simplest of operations such as cleaning a plug and bore, fitting a new washer and screwing it up with a calibrated torque wrench set to the correct value is completely beyond the capabilities of the "lads" to which these tasks are generally delegated. The resulting damage is therefore pretty much a foregone conclusion.
In skilled hands, a helicoil threaded insert can be used to make an excellent repair, although a modified sealing washer may then be required.
659.
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I agree, a helicoil would be the most cost effective way of repairing this problem. Although if it's a newish car, and it has never been elsewhere but the dealer, then you might ask the dealar for a contribution towards the new sump, because it has been damaged by them, and sumps are definitely not wear and tear, or routine service items.
Another practical route forward, if the sump plug seals this time, would be to get the garage to suck the oil out of thedipstick tube for future services. Having said that, I'm not sure how easy I would sleep knowing that the sump plug may not be held in place properly.
Number_Cruncher
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Having said that, I'm not sure how easy I would sleep knowing that the sump plug may not be held in place properly.
You Loctite 271 it.
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Mike Farrow
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Hmm, it's just that in comparison, the heli-coil repair will almost certainly lead to a stronger joint than the original bolt threaded into the cheese soft alloy sump - the load is effectively passed into a larger shear area of alloy via the comparitively strong heli-coil. In previous work, I have routinely specified heli-coils as original equipment on safety critical aerospace parts, and their solid counterparts, tappex inserts, for repairs to rail rolling stock - carefully fitted (as per 659's caveat), they can make a very strong joint.
In comparison, the sump-plug threaded back into an already damaged, and perhaps originally marginal, cheese soft sump - even with some loctite goo - would be at best a joint of unknown integrity.
Number_Cruncher
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The thread strips on the alloy sump, not the steel plug. Try helicoil, if you know someone who can do it. If that doesn't work, sump from breaker.
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Since it was the main dealer that did the damage, ask them to cope with the helicoil solution. It isn't expensive and it does work.
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I agree - Helicoil in situ - much cheaper than a new sump.
The original was probably damaged last time it was serviced (by careless technicians). This damage should not happen - you are paying your £70+ an hour to have 'skilled technicians' work on your car, not cack-handed spanner monkeys.
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The person who informed you of the damaged thread is not necessarily the culprit. The real culprit is the person who last did up the nut.
Rather than fit a helicoil insert, you could simply tap in a larger diameter to take a larger diameter nut. After all, tapping in a larger thread is what you will have to do to fit a helicoil. I would not inserts a helicoil into a damaged thread.
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Tapping a larger thread and using a new bigger plug sounds the easiest solution. Then don't let the garage touch it in future - do it yourself.
An alternative might be, if the plug points horizontally rather then on the underneath, might be to tap and permanently fit a very short length of steel gas pipe, and then use a steel cap on the end for draining.
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Thanks for your thoughts everyone.
I'm particularly interested in the comment that the cause was almost certainly the mechanic who did the job the last place it was serviced. The interesting thing is that the last place it was serviced was a different main dealer - one with a better reputation than the one that was doing the work yesterday! Oh dear.
That said, if the main dealer who was doing the work yesterday knew his stuff, why didn't he mention the possibility of a helicoil job to me?
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Because it's not in the procedures!
I would have a helicoil put in, but not by the dealer, by somewhere that does it all the time.
I had one put in my last car for about £35. It is like a coil sprint which winds up as they screw it in thus becoming thinner, and then when it's in, it can expand to push tightly against the sides of the hole, I think a tang also bends round on the inside of the hole opening to stop it becoming unscrewed when you unscrew the plug. It felt more solid than how it was originally which had that awful soft aluminium feel.
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As mentioned above, there's absolutely no point putting a heli-coil into a damaged thread. What happens is that you re-tap the hole larger than the original size, and screw in the heli-coil. The tang is there purely to allow you to thread the coil into place, and it is usually best to break it off, and withdraw it once the coil is fitted - there is a specially weakened section in the coil to allow this.
Some heli-coil sizes are alo available in a locking type, where one or two of the coils are deformed, and so, they grip the bolt, in an analogous manner to a nylon insert in a locking nut.
I allways use loctite between the outside of the heli-coil and the part I'm repairing - it prevents the heli-coil winding itself out as you withdraw the bolt - which is especially likely with the locking types.
After fitting the helicoil, you are left with a good steel thread, which should be the same size as the original was in the alloy. As 659 mentioned, you may need to use a different or modified washer to obtain a good seal.
There's a good chance that heli-coils weren't mentioned because that garage doesn't have the tools and/or the experience in using them - it is more of an engineering jobbing shop repair than a car workshop repair.
Number_Cruncher
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My BMW R100 RS bike had a heli-coil in holding the engine oil drain plug, for ages. It was never a problem. EPU976Y is still going I expect it's still there. It was only two years old at the time it needed it.
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Lots more profit for the garage in selling you a new sump and charging the labour to fit it!
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Broadly speaking, will a heli-coil be as good as new, almost as good as new, or better than new?
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IMO, better - much better.
Number_Cruncher
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Sounds like a heli-coil is what I should go for. How do I find a place that will get me one and fit it?
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Any good local engineering shop-see your "yellow pages";can probably be done in-situ just by draining the sump.
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another alternative would be to braze/weld a nut with a thread size the same as your sump plug over the hole which would be stronger than the original
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another alternative would be to fit a draining valve which stays in the hole permenantly ,the oil is drained by removing the brass cap and fitting a drain pipe which opens the valve
this is a very mess free way of changing oil as the drain pipe fits in to a container to eliminate any spills or dribbles
I think from memory the last one I bought was about £14
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Here's the webpage of a UK supplier of Heli-coils
www.hillcliff-tools.com/helicoil.html
It may be quicker to ask them if they supply heli-coils to anyone in your area. If you draw a blank there, it may be worth ringing round until you find someone who has done such a repair, and will do so again.
The vital part of the installation is to ensure that the new tapped hole is accurately at right angles (ideally, within half a degree) to the sealing surface on your sump. If not, there are two bad consequences - the obvious one is that the sumpl plug won't seal, and the more subtle one is that the sump plug wont share load around the circumference equally when you tighten it up, which can lead to a localised failure.
I should clarify, that I recommend the use of a small amount thread lock between the outer surface of the helicoil and the sump**, and that no loctite is used between the sump plug and the helicoil. The danger which you want to avoid is the heli-coil unsrewing from the sump when you take the plug out next time.
** An amount which is enough to lock the insert in place, but not so much as to run through the gps in the coils to the inner surface of the heli-coil.
It's also worth obtaining a couple of spare inserts in the right size. If an insert does screw out when you take the sump plug out, then it is child's play to thread a new one in, and break the tang, using long nose pliers or long nosed mole grips.
Another possibility is Ensat by;
www.tappex.co.uk/tappex_products.htm
As these self tap, they are far less likely to unscrew in normal use - however, if they do unscrew, you are left with a less easy repair route. The same warnings about ensuring these are fitted normal to the sealing surface applies - as these are self-tapping, it can be difficult to acheive this accurate alignment in-situ.
Number_Cruncher
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Update. Helicoil fitted today. So far, so good!
A friend who is a mechanic suggested that I contact the following people, who did the job.
www.autoheadrecon.com/
Thanks all.
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It looks to be very common. I had a 99 Punto for a couple of years it was an early 1.9 JTD with a very flimsy 8 mm allen key type disc shaped thing. At it 30K service the dealer said it was rounded off and they would have to fit a new sump (it had been serviced) twice before by them at 10K and 20K. I refused and no warranty claim was entertained.
It came off the ramps and I went straight to my local independent with a stilson to the grip the edge removed it quickly and phoned fiat for a new plug and filter. He then said "sorry but I should have asked how long the plug will take as it not going to be on an on the shelf item" (his view) 35 minutes later van turns up with said parts and i'm back on the road quickly.
Things this taught me - main dealers have often their most junior members of staff doing the mundane tasks and the lack of experience shows. The "workshop manual" says uses an 8 mm allen key and a very low torque setting not an air gun. Secondly that recomendation and the fact that they work on every make of car builds something we all need in life - experience and that they have (three generations working) there.
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The torque setting for my MB sump plugs is a mere 25 Nm.
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