Technical Would a hot engine cause leaking diesel to catch fire?

[stewart54]

Sorry to appear to be rather ignorant but following a recent diesel fuel leak from the fuel filter casing in my Ducato motorhome, I was wondering if the diesel could have caught fire by coming into contact with hot parts of the engine e.g. exhaust?


Any advice would be appreciated.


Happy New Year to all when it comes.

 

[Most Easterly Pandas]

Sorry to appear to be rather ignorant but following a recent diesel fuel leak from the fuel filter casing in my Ducato motorhome, I was wondering if the diesel could have caught fire by coming into contact with hot parts of the engine e.g. exhaust?


Any advice would be appreciated.


Happy New Year to all when it comes.

Not normally no, Diesel is often very hard to light, and normally requires a wick / debris etc to maintain the fire.

It'll normally just smoke and smolder.

 

[g8rpi]

Hi,
As most easterly pandas says, this would not normally cause a fire, but it most certainly could. The flash point of diesel is around 50 to 90 degrees C depending on the particualr batch. This means if there is an ignition source (open flame or spark) and the diesel is this hot it can ignite. The eging bay has several items that could heat diesel to the flash point. There few ignition sources in a moden diesel car, the most likely is the starter motor (brush arcing) if you tried to re-start it after the leak. The autoignition temperature of diesel is about 210 deg. C. This is the temperature of a hot surface which will ignte diesel dropped on it. Clearly the exhaust manifold, turbocharger and exhaust will be above this temperature so the risk is real. In practice dropping a fuel on a hot piece of metal is unlikely to get it to ignite, but you should NOT RUN THE ENGINE or DRIVE any car with any fuel leak. Note that a small leak from the common rail is highly likely to be atomised and thus much easier to ignite. There is a personal hazard from high pressure diesel leaks too. A fine high pressure jet of fuel can penetrate the skin and be njected into tissues. This is very painful and hard to treat. Often the only cure for the resulting necrosis is amputation!

Don't try to find the source of a leak, or worse try to stop it, with your hands.
While I'm a professional electronics engineer, I work in aviation including design of fuel systems, and diesel is very similar to Jet A aviation fuel. I'm currently working on a fuel system design and anything in contact with fuel must stay under 200 deg C and not be capable of causing a spark of more than 200uJ to prevent ignition. This includes fault conditions. I also "play" with small jet engines as a hobby. The fuel leak skin injection injury was known in the aircraft industry long before common rail diesels.
Here are links to marine investigations into fuel leak fires
http://www.maib.gov.uk/publications/investigation_reports/2007/Calypso.cfm
http://www.maib.gov.uk/publications/investigation_reports/2011/oscar_wilde.cfm

Robert.

 

[stewart54]

Hi,
As most easterly pandas says, this would not normally cause a fire, but it most certainly could. The flash point of diesel is around 50 to 90 degrees C depending on the particualr batch. This means if there is an ignition source (open flame or spark) and the diesel is this hot it can ignite. The eging bay has several items that could heat diesel to the flash point. There few ignition sources in a moden diesel car, the most likely is the starter motor (brush arcing) if you tried to re-start it after the leak. The autoignition temperature of diesel is about 210 deg. C. This is the temperature of a hot surface which will ignte diesel dropped on it. Clearly the exhaust manifold, turbocharger and exhaust will be above this temperature so the risk is real. In practice dropping a fuel on a hot piece of metal is unlikely to get it to ignite, but you should NOT RUN THE ENGINE or DRIVE any car with any fuel leak. Note that a small leak from the common rail is highly likely to be atomised and thus much easier to ignite. There is a personal hazard from high pressure diesel leaks too. A fine high pressure jet of fuel can penetrate the skin and be njected into tissues. This is very painful and hard to treat. Often the only cure for the resulting necrosis is amputation!

Don't try to find the source of a leak, or worse try to stop it, with your hands.
While I'm a professional electronics engineer, I work in aviation including design of fuel systems, and diesel is very similar to Jet A aviation fuel. I'm currently working on a fuel system design and anything in contact with fuel must stay under 200 deg C and not be capable of causing a spark of more than 200uJ to prevent ignition. This includes fault conditions. I also "play" with small jet engines as a hobby. The fuel leak skin injection injury was known in the aircraft industry long before common rail diesels.
Here are links to marine investigations into fuel leak fires
http://www.maib.gov.uk/publications/investigation_reports/2007/Calypso.cfm
http://www.maib.gov.uk/publications/investigation_reports/2011/oscar_wilde.cfm

Robert.

Many thanks for this - it has helped to clarify my gut instinct that any fuel leak can be a potential problem and that if there is a latent defect with the fuel filter housing used on Ducatos then DVSA/VOSA MUST ACT and issue a recall notice as soon as possible

 

[CDK]

I could write a book about that miserable UFI fuel filter housing.
On a hot summer day I caused panic when I entered the ferry because fuel gushed from the filter. The crew stood ready with fire extinguishers and insisted I immediately removed my vehicle. I of course complied and back on shore found half the engine bay soaked with fuel. But no fire!

This was the 2nd time the seal failed after descending on a mountain road. When climbing the engine bay temperature rises, the filter housing expands and the seal softens. Going down no fuel is used so there is maximum pressure, causing the seal to slip away. It happened 3 more times, the last time in Italy the housing burst open, spilling half the tank's contents on the road.
We were towed to a Fiat dealer where the housing was replaced at the expense of EUR 300.

Whenever my wife says she smells fuel I stop and inspect, until now everything seems to be OK.

 

[stewart54]

I could write a book about that miserable UFI fuel filter housing.
On a hot summer day I caused panic when I entered the ferry because fuel gushed from the filter. The crew stood ready with fire extinguishers and insisted I immediately removed my vehicle. I of course complied and back on shore found half the engine bay soaked with fuel. But no fire!

This was the 2nd time the seal failed after descending on a mountain road. When climbing the engine bay temperature rises, the filter housing expands and the seal softens. Going down no fuel is used so there is maximum pressure, causing the seal to slip away. It happened 3 more times, the last time in Italy the housing burst open, spilling half the tank's contents on the road.
We were towed to a Fiat dealer where the housing was replaced at the expense of EUR 300.

Whenever my wife says she smells fuel I stop and inspect, until now everything seems to be OK.

Sorry to learn of your experiences. During May/June of this year I toured Norway with lots of mountain driving but no problems - but then the filter had not been replaced!
I have done an email to BBC Watchdog about my particular problem and also an email to AutoExpress as the only way it seems to get Fiat to act is to cause as much embarrassment as possible - as witnessed by the reaction to the Fiat 500 problem of not being able to get up hills.

 

[CDK]

I've heard Fiat changed the construction starting in 2014....
Some say there is nothing wrong with the UFI filter housing because it is used in several other vehicles as well. I don't know if the others also have 5 bar fuel pressure.

Fact is I found several discarded UFI filter housings behind the building where our van was repaired.

 

[stewart54]

I've heard Fiat changed the construction starting in 2014....
Some say there is nothing wrong with the UFI filter housing because it is used in several other vehicles as well. I don't know if the others also have 5 bar fuel pressure.

Fact is I found several discarded UFI filter housings behind the building where our van was repaired.

DSVA emailed me today to say they were aware of the leakage issue but following previous investigation there is insufficient evidence to demand a recall. It is implied by Fiat that failure to use "special tools" causes leaks to occur on servicing or repair to the filter casing. Are these special tools only available to franchised Fiat garages - if so anti-competitive and in breach of EU rules. I have replied to DVSA and copied my MP, BBC Watchdog, Motorhome Channel, AutoExpress into it as well as posting on the Caravan Club website

 

[Techno100]

The tool is readily available on ebay for under £17
The same filter is used on Relay & Boxer along with very many other vehicles.
I am in complete agreement with their report.

ANY 5843 tool will do the job, as you see this one is being sold for Vauxhall/Opel as they also use the UFI filter units
http://www.ebay.co.uk/itm/311144432058?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

My guide https://www.fiatforum.com/ducato/357166-x250-ufi-fuel-filter-service-part-ii.html?p=3544663