Interpretation of fuel analysis

[Sylus]

Hello everybody.
This customer has been complaining about fuel filter saturation.
This engine is for interstate bus application here, running on Biodiesel 5.
He states that his filters gets clogged too often.
Fuel sample has been taken from its fuel tanks. The results are attached.
I suspect of contamination of hose degradation (hoses looked from not-so-good quality). But I also suspect from wear metals from the engine.
Fuel tanks are made of stainless steel.

Could you please cast an eye to the attached results and shed some light on it?
What elements do I have to look in the results?
Keep in mind the rubber hoses are suspicious.

My try: ICP plasma can only detect particles up to 8 microns. That could be the reason why even this results show high PQI value, it shows no Iron ("Fe") in the wear analysis. It says "Fe= 0 ppm".
But it shows an elevated Sulphur value "S=60 ppm". Could it be from vulcanized rubber? It is composed of sulphur.
Since the fuel here is around 30 ppm, this value is out of range.

Any help is welcome.
Thank you.

 

[3DDave]

Sorry - to attach a file one needs to copy and paste the link that is generated by the upload process into your message. In any case, the attachment is not attached.

 

[TugboatEng]

What are the rubber hoses? If you are in the USA they have a SAE 30R number that will explain the materials of construction of the hose. I don't think I've ever seen a hose fail on such a micro scale that it would clog a filter. I have seen hoses fail on a macro scale that would clog the filter housing.

I don't think any automotive hose material has sulfur in it. Your likely materials for fuel lines are buna-N or some modification such as buna-pvc or HNBR, Viton, or maybe Hypalon.

Also, if the filter is clogging you need to send the filter in for analysis, not the fuel. Make sure you run an ATP test to check for biological activity.

 

[btrueblood]

Sulfur is a common curing additive for most rubbers, including the ones you mentioned, Tug. Peroxide cures are available but typically more expensive, not sure if they get specified for fuel hoses. I'd also wonder if the sulfur compounds are not present in the original oils used to create the biodiesel, and not properly washed out in the conversion process?

 

[Hoxton123]

The have been reports across Europe about fuel filter blocking on diesel engines running on biodiesel, both road vehicles and agricultural.

The exact cause of these problems has not yet been identified but appear to be due to cold flow
waxing, and possibly dirty bulk storage tanks at end user’s sites.

Biofuel(FAME) is hygroscopic so any water in tanks will be absorbed into the fuel. Water is also a catalyst to bacterial growth which not only degrades the fuel but can cause filter blocking.

Its all a little bit random, but seems to be concentrated in certain areas, and is worse in winter.

I hear that our vehicle recovery teams are bagging any blocked diesel filters and sending them for analysis.

If I hear any more, I will post.

 

[NickJ67]

Some years ago I briefly ran my C4 Audi A6 2.5TDI on biodiesel. Car already had c.200k miles at that point, all done on regular diesel.

I was warned that filter clogging might be an issue and was advised to carry a spare. According to the bio supplier, the clogging risk was due to the bio loosening any deposits/sediments left by the years of dino diesel and would go away after a few fill-ups.

Filter clogging was indeed an issue. I got quite quick at changing filters by the roadside (inline manual primer absolutely essential) when the car would refuse to cruise at reasonable speeds or go up hills anymore.

I maybe put 5 or 6 tanks through in total (perhaps 350/l over 4k miles - this car goes a long way on a tank) and about the same number of filters, with no particular sign of a reducing clog-rate. I got bored with that and went back to regular pump fuel. Most of the biofuel came from the same place and was made with used vegetable oil mixtures. Exhaust smelt interesting - usually "chip shop", but distinctly spicy on one occasion - curry house I guess! Obviously the vendor claimed it was thoroughly filtered. Hard to believe it was still dino residue after that much bio..... I will say though, on returning to dino, the mpg was the best it had ever been for several months after, so perhaps there was a cleaning effect! There wasn't anything especially obvious or interesting in the couple of filters I cut open.

I was also warned that I might have problems with hoses and pump seals, which did not materialise. Possibly because I was only using it for a fairly short time. Still have the car 10 (maybe) years and 135k later, so no harm done.

Nick

 

[RodRico]

There's some good information in this article and some technical discussion in this research paper.