Swarf in Diesel Tank

[Eednud]

Just put my 2 year old, 60,000 mile VW Caddy Bluemotion in for a service at Main Dealer as per the Leasing company requirements.

Garage says there is Swarf or "glittering" in fuel tank and they have to replace every part of the Fuel System apart from Tank and fuel lines! and I wont get the van back for another week..

The van is leased, so not really my problem, or so I thought. They now say this could have been caused by putting petrol in the tank at some point.

I can see the Leasing company trying to use this to get me to pay for the repairs. I know the van has never had petrol in the tank, as I am the only person who has ever driven it.

What is the likely cause of this? I would have thought if a component was breaking down, then that should be the only part to be replaced, as the fuel filter would have caught everything else. It could also have been a fault at the petrol station with their filters.

I don't think they know where the swarf came from, and a easy fix is to replace everything.

All I do know is I won't be paying for it, and am quite enjoying the Caddy Sportline I have as a Courtesy Van.

[Adrian]

If the pump is starting to wear internally, that'll generate swarf after the filter - and it'll pass into the rail, the injectors, the return lines back to the tank then out again through the lift pump before being caught in the filter.

Common rail diesels are incredibly precisely machined - they have to be, running fuel pressures of up to 2,000 bar. Yes, two thousand BAR. Damn near 30,000psi. They rely on the fuel for lubrication - and even relatively small amounts of contamination with petrol can remove that lubrication, causing rapid wear...

[Eednud]

Would think VW would cover that under Warranty then. I would think there was more than 1 fuel filter in the system as well

[Tim Lamb]

Isn't there also an issue with low sulphur diesel not lubricating the pump properly?

[newshound]

To my mind the term "swarf" describes the sort of metallic debris generated by turning, milling, or drilling, i.e. relatively large curly deformed bits of metal. The wear you will normally get in a diesel pump will be micron-sized and if you collect it it will look like black sludge, not recognisably metallic at all except perhaps in a high powered optical microscope or an SEM. I don't think it will be "glittering" to the naked eye, it would be too small.

But I suppose that sufficiently abrasive debris in the system, something like sand, might cause scoring in the pump parts (either the lift or the injector pump?), and perhaps glittery debris. In that case total replacement sounds like the right strategy (especially if someone else is paying).

I'd agree that petrol in the system could lead to pump wear.

[Tim+]

Most warranties don't cover misfuelling, even if you don't recall an episode. In Northern Ireland they used to have a big problem with dodgy fuel and whatever the cause, fuel systems were not covered by warranties.

Can see how this would help. Once petrol or other low lubricity fuel has reached the fuel pump, the damage is done. Extra filters won't stop that.

Tim

[JimK]

Sounds like a bent dealer to me.

Care to name?

Jim K

[Andy Burns]

I think it's easy for them to blame misfuelling, where petrol wouldn't provide sufficient lubrication to the diesel pump (some of which operate at around 30,000 psi) so causing wear in the pump, and the excess fuel returning to the take would take the swarf with it.

If you know that hasn't happened, then I don't see how they can "prove" it did

[Adrian]

ITYM "wouldn't", if it is fuel system contamination.

Between the pump and the injectors...? With 30,000psi...?

[Tim+]

It's easy for owners to deny misfuelling too. I think garages are more inclined to believe the evidence than the story.

Tim

[John Rumm]

And it would not be difficult for a bent garage to lob a few litres of petrol in it now and run it through the system - that way any investigation later would find evidence of petrol contamination.

[Harry Bloomfield]

Adrian formulated the question :

You are forgetting the under-bonnet diesel filter!

Pump and strainer in the tank, piped forward to the under bonnet filter, which catches all of the fine material. From there it feeds onto the HP pump, the rail, injectors. Any surplus then returns to the tank maybe via a fuel cooler. If there is a problem with swarf, that under-bonnet filter should catch it and it would show there.

If there is swarf in the tank, it has either been there from new, or is coming from the HP pump, or perhaps from the in tank pump - but if the latter, it must have escaped via the strainer the WRONG way, the reverse direction to the flow.

I see no reason to replace anything - apart from the component which is failing, if there is one. The system can simply be flushed out, the old filter checked and maybe replaced. Sounds like the garage are turning a drama into a crisis.

[Harry Bloomfield]

Petrol has no lubrication properties, which would cause massive wear on the LP pump and the HP pump.

[Gazz]

but like someone else pointed out, what part of the service were they doing when they discovered this 'glittering' in the fuel tank? that's what you have to ask them.

is sticking a boroscope down the tanks filler neck part of the servicing procedure? assuming this is a typical small van with a fuel tank under the floor and a filler tube that winds it's way around things to get to the filler hole, i think the last vans that had fuel tanks like trucks with the filler neck and cap part of the tank it's self (hence you could see into the tank when you removed the cap) was the square shape - pre~99 Iveco daily, and the square shape merc's.. 609, 811 and so on.....

And even then it's not part of the service schedule to look in the tank whilst shining a torch in there, Tho' did once have to remove the fuel tank from a merc 609 to clean it out, but that was because it had sat with the cap missing for months at a coachbuilders who were converting it to a recovery truck, they went bankrupt mid build, and it was spring time, so a blue tit built a nest in the tank..... knew that before i emptied the tank as i kept getting blue and yellow feathers in the pre-filter bowl every time the engine died from fuel starvation.

[jgh]

If you've only put a small amount of petrol in a diesel tank aren't you supposed to fill it to the top with diesel to dilute it and hammer up and down the motorway for a bit to burn it off through the engine?

jgh

[Harry Bloomfield]

[e-mail] brought next idea :

A small amount will do no harm (say 5%), but best to then keep the tank filled up a few times, each time there is room to put some in, so as to dilute in down as soon as possible. Hammer it - no reason to, just drive it normally.

[Adrian]

No, I'm not.

Yes, exactly.

Which is exactly what I suggested.

Because the swarf has circulated through the entire system, having started from the HP pump, before being stopped by the filter just before the HP pump.

[Adrian]

Changing the fuel filter involves plenty of fuel spillage, and the swarf/"glitter" would show up under the workshop lights.

[Eednud]

It was in for its 60K service, also the cat convertor light was on, and intermittently the Engine management light would come on, so I asked them to look at that.

I assume they found the swarf in the fuel filter, when it was swapped out, and then tried further investigation.

It runs fine, but its down to the lease company to authorise any work.

[Eednud]

Like I said, it has never had any Petrol in the tank. So this is not the cause.