Garage possibly caused engine damage

[Walter Sobchak]

A couple of weeks ago I took my car in to get the glow plugs changed, got a call the next day to say glow plugs all done but car is running rough (which it wasn’t before it went there) they will investigate in the morning and let me know.
Apparently it seemed a bit better and they have said a bit of carbon went into one of the cylinders and will burn off and all will be fine soon.
Picked it up, drove it home and to work the next day, it’s running like a bag of spanners,misfiring,especially at idle, overfueling from the amount of smoke it kicked out and strong smell of diesel in the cabin.
I bought it back to them and got told the next day they’d run something through the fuel system and it was much better-it wasn’t, and they were too busy to look again until end of last week.
Now been told it’s been plugged in and cylinder 3 is misfiring and compression is down, potentially could be an injector but might not be.
Spoke to a friend who’s a mechanic and he didn’t think an injector would be likely to cause this and likely there’s scoring and damage to the cylinder which would be very labour intensive to deal with, I’ve refused to take the car away again, bearing in mind it’s probably worth 3k absolute max it’s not going to be worth putting an engine in or rebuilding the current one.
Could anyone offer any advice on where I stand legally on this as it definitely wasn’t running wrong before it went in, just needed glow plugs!, I have got them admitting some carbon dropped into the cylinder l etc on a voicemail.

[Matt_E_Mulsion]

Have they snapped one trying to remove it and let debris fall into the cylinder whilst trying to extract the broken bit?

[bungz]

What engine?

Sounds like something has gone into the bore...

Compression test is needed now.

[Walter Sobchak]

It’s the Mercedes 3 litre V6 CDI engine, it’s also a complete pig to start now too, even worse than it was before the glow plugs were done and runs very rough at idle but is slightly better with some revs, something is definitely very wrong with it that wasn’t before.

[Marc p]

Depending on the mileage of the vehicle, replacing glow plugs can be far more complicated than most would assume. For a higher mileage older car (10+ years old and over 100k miles), most knowledgeable garages will inform the customer that although it may be a simple job, there is a chance that the costs could be much higher if it requires head removal.
This is due to two reasons, firstly, they can shear off and require drilling out and secondly, they can form a ‘bulb’ of hardened carbon on the tips that means they can’t fit through the hole without breaking the carbon off.
I know of one friend of mine that after making the customer aware of the issues, will also film the removal to show the customer in case of any issues.

In your case, I’d most definitely say that they have forcefully removed a glow plug with carbon build up that has then broken off and dropped into the cylinder and due to how hard the carbon build up on glow plugs is, it has then scored a cylinder and created the issue described.

[bearman68]

May I offer an alternative view.
Maybe the injector has failed, is leaking fuel into the piston, and washing the oil from the piston walls, resulting in a poor seal and low compression? Had this happen loads of times.
And because the injector is leaking, it can't build fuel pressure, and is hard to start.

No-one will do it, because it's hard work, but a pressure / time check on the fuel system would be a test that would give a load of information.

[Walter Sobchak]

Marc p said:

Depending on the mileage of the vehicle, replacing glow plugs can be far more complicated than most would assume. For a higher mileage older car (10+ years old and over 100k miles), most knowledgeable garages will inform the customer that although it may be a simple job, there is a chance that the costs could be much higher if it requires head removal.
This is due to two reasons, firstly, they can shear off and require drilling out and secondly, they can form a ‘bulb’ of hardened carbon on the tips that means they can’t fit through the hole without breaking the carbon off.
I know of one friend of mine that after making the customer aware of the issues, will also film the removal to show the customer in case of any issues.

In your case, I’d most definitely say that they have forcefully removed a glow plug with carbon build up that has then broken off and dropped into the cylinder and due to how hard the carbon build up on glow plugs is, it has then scored a cylinder and created the issue described.

I’d agree with what you’ve said has probably happened, given the cars value and the amount of work it’s likely going to need to remedy it I don’t know what to do going forward.
Yes the garage have caused it technically but if it’s something that can easily happen due to age and mileage do they have any responsibility or have I just got to suck it up and have a worthless 2.5 tonne paperweight.

[NRG1976]

Marc p said:

Depending on the mileage of the vehicle, replacing glow plugs can be far more complicated than most would assume. For a higher mileage older car (10+ years old and over 100k miles), most knowledgeable garages will inform the customer that although it may be a simple job, there is a chance that the costs could be much higher if it requires head removal.
This is due to two reasons, firstly, they can shear off and require drilling out and secondly, they can form a ‘bulb’ of hardened carbon on the tips that means they can’t fit through the hole without breaking the carbon off.
I know of one friend of mine that after making the customer aware of the issues, will also film the removal to show the customer in case of any issues.

In your case, I’d most definitely say that they have forcefully removed a glow plug with carbon build up that has then broken off and dropped into the cylinder and due to how hard the carbon build up on glow plugs is, it has then scored a cylinder and created the issue described.

Very informative post, thanks for sharing.

[bearman68]

NRG1976 said:

Very informative post, thanks for sharing.

I don't disagree with the snapped plugs (had it), and the carbon build up (had it), but be careful of confirmation bias.

[Marc p]

Walter Sobchak said:

I’d agree with what you’ve said has probably happened, given the cars value and the amount of work it’s likely going to need to remedy it I don’t know what to do going forward.
Yes the garage have caused it technically but if it’s something that can easily happen due to age and mileage do they have any responsibility or have I just got to suck it up and have a worthless 2.5 tonne paperweight.

Personally, I don’t confess to be knowledgeable enough in the legalities to know where you stand.

That being said, from a technical point of view, I’d say it definitely would be the garage’s fault. Carbon buildup wouldn’t just ‘fall off’ with a light touch, it would require quite a bit of force and any decent mechanic would know exactly what the issue would be.

You could say that carbon buildup requiring head removal is something that easily happens is valid, but to break it off and causing major cylinder damage is not something that easily happens, that’s akin to someone dropping something into the bore and saying it’s something that just ‘easily happens’.

[Marc p]

bearman68 said:

NRG1976 said:

Very informative post, thanks for sharing.

I don't disagree with the snapped plugs (had it), and the carbon build up (had it), but be careful of confirmation bias.

I do agree with this, although my post was an educated guess that was taking into account the OP had standard glow plug issues, then following replacement, immediately suffered far more serious sounding issues. I would have another garage put a camera down the bore to investigate and get a better understanding.

[bearman68]

Marc p said:

I do agree with this, although my post was an educated guess that was taking into account the OP had standard glow plug issues, then following replacement, immediately suffered far more serious sounding issues. I would have another garage put a camera down the bore to investigate and get a better understanding.

I'm still thinking the low compression on (let's say) 1 cylinder doesn't account for the smelling of fuel, and the 'overfueling' and the hard to start. I have a seriously difficult time believing all 6 cylinders are toasted to the extent it won't start. That's, what, a compression ratio of 12 to 14 to 1, something like that. Maybe 1 cylinder, but not all 6.
So it seems to me to be worth a look to see where the diesel smell is coming from. It might easily be a leak off rail that has been disturbed or damaged, and that might be causing the issues with the starting, and running rough on idle. Not saying it is, but it's an easier look than the alternative.
If it were in my shop, I would then carry out a compression test, and check the fuel rail pressure v time graph on an oscilloscope. Both these tests will give a good indication of the likely fault in a manner that might prevent assumption.
But, there are more ways than 1 to skin a cat, and my test system might well be different to someone else's. I've never been terribly successful with a camera on a stick. But the immediate future looks like a series of diagnostic tests to prove or disprove various ideas.

[Walter Sobchak]

Marc p said:

Personally, I don’t confess to be knowledgeable enough in the legalities to know where you stand.

That being said, from a technical point of view, I’d say it definitely would be the garage’s fault. Carbon buildup wouldn’t just ‘fall off’ with a light touch, it would require quite a bit of force and any decent mechanic would know exactly what the issue would be.

You could say that carbon buildup requiring head removal is something that easily happens is valid, but to break it off and causing major cylinder damage is not something that easily happens, that’s akin to someone dropping something into the bore and saying it’s something that just ‘easily happens’.

I’ve read up a bit on it and legally speaking it does seem they are required to remedy it, I’ve left it with them at the moment and do get the feeling they’re fobbing me off as they mentioned the carbon dropping down already and no doubt know how much damage has been done and hope I lose patience and go away I expect.
The thing is I’m not unreasonable, I know mistakes/accidents do happen and I realise that fixing it is going to be very labour intensive and/or possibly require a replacement engine, on a car that’s worth at the most 3k it just seems beyond economical repair to fix it and I do need to either have it fixed or replace it in a timely fashion because my current commuting options are either a superbike or a 30 year old Landcruiser which although a brilliant car isn’t the most fun on the motorway!.

[Marc p]

bearman68 said:

Marc p said:

I do agree with this, although my post was an educated guess that was taking into account the OP had standard glow plug issues, then following replacement, immediately suffered far more serious sounding issues. I would have another garage put a camera down the bore to investigate and get a better understanding.

I'm still thinking the low compression on (let's say) 1 cylinder doesn't account for the smelling of fuel, and the 'overfueling' and the hard to start. I have a seriously difficult time believing all 6 cylinders are toasted to the extent it won't start. That's, what, a compression ratio of 12 to 14 to 1, something like that. Maybe 1 cylinder, but not all 6.
So it seems to me to be worth a look to see where the diesel smell is coming from. It might easily be a leak off rail that has been disturbed or damaged, and that might be causing the issues with the starting, and running rough on idle. Not saying it is, but it's an easier look than the alternative.
If it were in my shop, I would then carry out a compression test, and check the fuel rail pressure v time graph on an oscilloscope. Both these tests will give a good indication of the likely fault in a manner that might prevent assumption.
But, there are more ways than 1 to skin a cat, and my test system might well be different to someone else's. I've never been terribly successful with a camera on a stick. But the immediate future looks like a series of diagnostic tests to prove or disprove various ideas.

OP stated that it’s a cylinder 3 issue as that’s the one that failed a compression test.

I agree that it’s all speculation on here and hard to diagnose without having the car in front of us, but when it comes to the fuel smell I’d hazard a guess that if cylinder 3 is down then the remaining injectors on the bank would be over fueling to compensate and giving the excess diesel smell(although this is assuming the smell is evident when stationary and not at speed)

[Marc p]

Walter Sobchak said:

Marc p said:

Personally, I don’t confess to be knowledgeable enough in the legalities to know where you stand.

That being said, from a technical point of view, I’d say it definitely would be the garage’s fault. Carbon buildup wouldn’t just ‘fall off’ with a light touch, it would require quite a bit of force and any decent mechanic would know exactly what the issue would be.

You could say that carbon buildup requiring head removal is something that easily happens is valid, but to break it off and causing major cylinder damage is not something that easily happens, that’s akin to someone dropping something into the bore and saying it’s something that just ‘easily happens’.

I’ve read up a bit on it and legally speaking it does seem they are required to remedy it, I’ve left it with them at the moment and do get the feeling they’re fobbing me off as they mentioned the carbon dropping down already and no doubt know how much damage has been done and hope I lose patience and go away I expect.
The thing is I’m not unreasonable, I know mistakes/accidents do happen and I realise that fixing it is going to be very labour intensive and/or possibly require a replacement engine, on a car that’s worth at the most 3k it just seems beyond economical repair to fix it and I do need to either have it fixed or replace it in a timely fashion because my current commuting options are either a superbike or a 30 year old Landcruiser which although a brilliant car isn’t the most fun on the motorway!.

What car is it that has the issue? I assumed it was the Landcruiser for your garage.

[bearman68]

Marc p said:

OP stated that it’s a cylinder 3 issue as that’s the one that failed a compression test.

I agree that it’s all speculation on here and hard to diagnose without having the car in front of us, but when it comes to the fuel smell I’d hazard a guess that if cylinder 3 is down then the remaining injectors on the bank would be over fueling to compensate and giving the excess diesel smell(although this is assuming the smell is evident when stationary and not at speed)

You sound like a top bloke. I run a workshop that specialises in hard to diagnose faults. We have tea breaks and discuss the tests done, the results, and what we think we should do next. I think you'd love those chats and the discussion around them.

[Marc p]

bearman68 said:

Marc p said:

OP stated that it’s a cylinder 3 issue as that’s the one that failed a compression test.

I agree that it’s all speculation on here and hard to diagnose without having the car in front of us, but when it comes to the fuel smell I’d hazard a guess that if cylinder 3 is down then the remaining injectors on the bank would be over fueling to compensate and giving the excess diesel smell(although this is assuming the smell is evident when stationary and not at speed)

You sound like a top bloke. I run a workshop that specialises in hard to diagnose faults. We have tea breaks and discuss the tests done, the results, and what we think we should do next. I think you'd love those chats and the discussion around them.

Oh most definitely I’d enjoy that

I’ll state that my business revolves around BMW’s so that is where my knowledge lies. These days I generally outsource general works to a friends garage, but if I can’t state what the problem is, I have great enjoyment in trying to find the issue (always had a love of puzzles).

When it comes to BMWs, the biggest thing that confuses most garages is injector failures on the petrol engines, diagnostics will always point to the wrong cylinders at fault due to the over/under fuelling cylinders compensating for the cylinder that is actually at fault.

[Richard-D]

Marc p said:

OP stated that it’s a cylinder 3 issue as that’s the one that failed a compression test.

I agree that it’s all speculation on here and hard to diagnose without having the car in front of us, but when it comes to the fuel smell I’d hazard a guess that if cylinder 3 is down then the remaining injectors on the bank would be over fueling to compensate and giving the excess diesel smell(although this is assuming the smell is evident when stationary and not at speed)

Does it work that way with a diesel? Wouldn't the engine accelerate uncontrollably if so?

[Marc p]

Richard-D said:

Marc p said:

OP stated that it’s a cylinder 3 issue as that’s the one that failed a compression test.

I agree that it’s all speculation on here and hard to diagnose without having the car in front of us, but when it comes to the fuel smell I’d hazard a guess that if cylinder 3 is down then the remaining injectors on the bank would be over fueling to compensate and giving the excess diesel smell(although this is assuming the smell is evident when stationary and not at speed)

Does it work that way with a diesel? Wouldn't the engine accelerate uncontrollably if so?

What your referring to is ‘engine run on’, but this is incredibly unlikely to be caused by over-fueling injectors as it would likely need pretty much every injector to be excessively over-fuelling and the managing ECU to completely fail to pick up the issue, without going in depth to how a diesel engine works in comparison to a petrol, the usual cause of ‘over-run’ is a blown turbo seal that feeds the engine with excessive amounts of oil.

Edited by Marc p on Tuesday 3rd October 00:56

[nismocat]

Marc p said:

OP stated that it’s a cylinder 3 issue as that’s the one that failed a compression test.

I agree that it’s all speculation on here and hard to diagnose without having the car in front of us, but when it comes to the fuel smell I’d hazard a guess that if cylinder 3 is down then the remaining injectors on the bank would be over fueling to compensate and giving the excess diesel smell(although this is assuming the smell is evident when stationary and not at speed)

That sounds like a load of BS to me.
Why would another injector overfuel to compensate, compensate for what?

Sounds like a valve is damaged not the bore so unburnt fuel is leaking out into the exhaust/plenum hence the smell.