Extreme cold cause sludge in fuel filter?

ericbaisch

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2006, Golf, Black
I recently traveled from Philadelphia, Pennsylvania to the Adirondacks in New York. I filled up with 13 gallons of diesel fuel just East of Watertown, New York. The temperature was -15 degrees Fahrenheit. After driving around 30 miles my engine began shuddering when throttle was advanced above about 70% maximum. I figured it was bad fuel with water mixed in that was plugging up the filter. I waited until I had consumed about 1/3 of the tank and purchased a fuel additive at a truck stop to address that symptom and topped off my tank. The situation seemed to get a bit better but was not corrected. In the hills of Pennsylvania I could not quite maintain the speed limit on the highest few.
As soon as I returned home I changed the fuel filter and the problem was corrected. I cut open my filter as I always to when I change it. Never before have I seen any sign of water or dirt. There was no water in my filter but it was filled with black sludge. See link to photo below.
https://www.amazon.com/photos/shared/OXLCE17xQuC07Et95kGb-g.pvOFbRDbcgMq1OgiA_y6Qp

Before I contact the service station that supplied the fuel to complain I wanted to ask others with more experience if the sludge could have been a result of the colder than normal temperatures causing sludge already in my tank to be released to plug my filter? Is that source of the sludge most likely the last batch of fuel that I purchased?
My car is a 2006 Golf TDI with 210,000 miles.
Regards,
Eric
 

Vince Waldon

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On a PD engine the black colour is normal, if that's what folks are reacting to.

The injection system is lubed with engine oil and there's always a little bit of leakage past the various o-rings, so over time the fuel system gets some soot in it, which collects at the fuel filter.
 

Vince Waldon

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Sure... not saying either water or "sludge" is normal... but black residue in and of itself is, particularly as the fuel system ages.
 

jmodge

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I would lean towards agreeing with Einstein on this one, looks like old nasty fuel. Had an old blazer that the fill tube to the tank looked like that. The truck had sat for a long time.
 

DivineChaos

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i would contact the place you got your fuel and notify them that you got bad diesel. looks like alge and old fuel. the old sulfer diesel never did this.
 

ericbaisch

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Philadelphia
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Thanks for all the replies. Based on the replies I am going to send the service station a letter stating it is probable that they supplied bad fuel to me along with a photograph of my fuel filter. They should have received other complaints based on how badly contaminated my fuel was. The fact I was not sure of is if the extreme cold might have caused contamination already in my tank to circulate into the filter. It seems that others have not experienced this.
Eric
 

soot1

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I would like to share a similar experience from many, many moons ago. It was December of 1989, and my employer at that time (located in East Syracuse, N.Y.) sent me on a business trip to Worcester, MA. At that time, I was driving a 1986 Jetta diesel, which had the 1.6L in-line four banger with a mechanical fuel injection pump, and the engine generated a whopping 52 hp. On the morning of the day when I hit the road, it was about -25 Celsius outside. I got in the car at 5AM, warmed it up a bit, and then got on my way. I drove about 10 miles thru areas where the speed limit was 40 or 45 before entering the Interstate 90, where the speed limit was 55. It only took a couple of minutes of driving before I felt noticeable stuttering. The needle of the engine temperature gauge never got to its usual resting spot when the engine was at normal operating temperature, so I figured the radiator is doing too good of a job, and decided to stop at the nearest coffee shop that was open at that hour, and ask for an unwanted cardboard box they had no use for. I then ripped a piece of the box and covered about 3/4 of the frontal area of the radiator, slammed the engine hood, and took off. In no time flat, the temperature gauge got to where it should be, the stuttering was gone, and, I was able to turn the heat on.

Moral of the story - diesel engines generate so little waste heat during operation that when they are exposed to these extremely low temperatures, they may not be even capable of reaching normal operation temperature, as was certainly the case with my 1986 Jetta. Is it possible that what you have experienced had the same root cause, rather than a clogged fuel filter?
 

DivineChaos

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I would like to share a similar experience from many, many moons ago. It was December of 1989, and my employer at that time (located in East Syracuse, N.Y.) sent me on a business trip to Worcester, MA. At that time, I was driving a 1986 Jetta diesel, which had the 1.6L in-line four banger with a mechanical fuel injection pump, and the engine generated a whopping 52 hp. On the morning of the day when I hit the road, it was about -25 Celsius outside. I got in the car at 5AM, warmed it up a bit, and then got on my way. I drove about 10 miles thru areas where the speed limit was 40 or 45 before entering the Interstate 90, where the speed limit was 55. It only took a couple of minutes of driving before I felt noticeable stuttering. The needle of the engine temperature gauge never got to its usual resting spot when the engine was at normal operating temperature, so I figured the radiator is doing too good of a job, and decided to stop at the nearest coffee shop that was open at that hour, and ask for an unwanted cardboard box they had no use for. I then ripped a piece of the box and covered about 3/4 of the frontal area of the radiator, slammed the engine hood, and took off. In no time flat, the temperature gauge got to where it should be, the stuttering was gone, and, I was able to turn the heat on.

Moral of the story - diesel engines generate so little waste heat during operation that when they are exposed to these extremely low temperatures, they may not be even capable of reaching normal operation temperature, as was certainly the case with my 1986 Jetta. Is it possible that what you have experienced had the same root cause, rather than a clogged fuel filter?
did you look at the picture of his filter? pretty nasty.
 
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soot1

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did you look at the picture of his filter? pretty nasty.
Yes, I did, and it does looks pretty bad. However, what immediately popped in my mind was a question: when was the last time the filter was replaced? From what the picture shows, I'd guess the filter has been sitting there for years, and that suggests neglected maintenance. I have hard time believing one tank of bad fuel would be responsible for a filter clogged up this badly and with stuff that is pitch black, unless the owner filled up with tar instead of diesel. Then I began wondering just how much fuel the engine uses in one second, and arrived at a surprisingly low volume - about 1.25 mL. Given how large surface the filter has, my guess is that such a small volume should have little difficulties getting thru, even if the filtering medium is clogged up this badly. That's why I suggested the stuttering may have had other cause than the filter.
 

DivineChaos

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Yes, I did, and it does looks pretty bad. However, what immediately popped in my mind was a question: when was the last time the filter was replaced? From what the picture shows, I'd guess the filter has been sitting there for years, and that suggests neglected maintenance. I have hard time believing one tank of bad fuel would be responsible for a filter clogged up this badly and with stuff that is pitch black, unless the owner filled up with tar instead of diesel. Then I began wondering just how much fuel the engine uses in one second, and arrived at a surprisingly low volume - about 1.25 mL. Given how large surface the filter has, my guess is that such a small volume should have little difficulties getting thru, even if the filtering medium is clogged up this badly. That's why I suggested the stuttering may have had other cause than the filter.
ah. do these have a lift pump or does the injection pump pull it right from the tank. Does unused fuel get returned to the tank or is it a nonreturn system. This is also why im in the habit of looking at the fuel as i pump it. These filters should be replaced yearly at a minimum. i really should check mine. who knows if the dealer really replaced both filters when it was serviced before being sold.
 

Lightflyer1

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Well the OP never mentioned when it was changed last. But he has been around since 2004 and should have been aware of the maintenance requirements and was surprised at the icky filter, so I would imagine it wasn't like this previously. He did mention that he always cuts them open when changed so I would imagine he is doing it properly. For this to just show up out of the blue like this something must be up. As icky as that is the station would have had many complaints by now if it was on their end. Contacting them is in order though.
 

DivineChaos

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Well the OP never mentioned when it was changed last. But he has been around since 2004 and should have been aware of the maintenance requirements and was surprised at the icky filter, so I would imagine it wasn't like this previously. He did mention that he always cuts them open when changed so I would imagine he is doing it properly. For this to just show up out of the blue like this something must be up. As icky as that is the station would have had many complaints by now if it was on their end. Contacting them is in order though.
and being he had a spare filter at home. and he knew to change that first. maybe the tank was almost empty and something got sucked up. wonder what the crud actually was.
 

DivineChaos

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Yes, I did, and it does looks pretty bad. However, what immediately popped in my mind was a question: when was the last time the filter was replaced? From what the picture shows, I'd guess the filter has been sitting there for years, and that suggests neglected maintenance. I have hard time believing one tank of bad fuel would be responsible for a filter clogged up this badly and with stuff that is pitch black, unless the owner filled up with tar instead of diesel. Then I began wondering just how much fuel the engine uses in one second, and arrived at a surprisingly low volume - about 1.25 mL. Given how large surface the filter has, my guess is that such a small volume should have little difficulties getting thru, even if the filtering medium is clogged up this badly. That's why I suggested the stuttering may have had other cause than the filter.
i think the issue you had was actualy the fuel starting to gel, causing it to be lean, cardboard raised the underhood temp helping the problem.
 

ericbaisch

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Philadelphia
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Original poster here. I change the filter about every 40k miles. I was about due for a filter change. I always drain fuel from the bottom of the filter into a clear glass container to look for water and also cut open the filter and pull apart the pleats of the filter to look for contaminants. I have driven VW diesel cars for almost 35 years. I have never before noticed any contaminants on my filter elements. My car was not coming up to full operating temperature. The problem did not correct itself even when driving in above freezing temperatures. I did read that the fuel is warmed by circulating engine oil so I guess there is a chance that a leak caused contamination of my fuel, although the substance clogging my filter seemed to be much thicker than engine oil.
Eric
 

Lightflyer1

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That being the case you can't really say it was the last place you got fuel from. It would be hard to pin anything down. It may have taken 40k miles to get this bad. I would half that mileage and change it early just to check. Have you found and fixed the cause of the car not operating at temp yet?
 

Scooby24

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Every 20k on a 2006/2004 tdi. Don't know which is correct, 2 listed differently.

http://pics.tdiclub.com/data/516/2006_All.pdf
Is that still accurate with today's Ultra Low Sulfur fuel? Per google, that started happening after 2006. As I understood it, the newer fuel has more growth potential for fungus and bacteria...I'd question the validity of that prior schedule when newer TDI's like mine are calling for filter replacements every 10k.
 

Scooby24

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You're right, my mistake...I was either told wrong or remembered wrong.

By Google I was referencing the year ULSD started being mandated and its increased growth potential.
 

Vince Waldon

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I'd question the validity of that prior schedule when newer TDI's like mine are calling for filter replacements every 10k.
Your car your rules... but it (common-rail) has a completely different fuel system than the previous generation (PD) and makes much higher demands on fuel purity.

As well, ULSD was in circulation before the previous generation was released, so chances are pretty good VW took that into account. :)

If you have any academic references on ULSD being more prone to fungus and bacteria please post 'em up...they would be interesting to read.
 

Scooby24

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Your car your rules... but it (common-rail) has a completely different fuel system than the previous generation (PD) and makes much higher demands on fuel purity.
As well, ULSD was in circulation before the previous generation was released, so chances are pretty good VW took that into account. :)
If you have any academic references on ULSD being more prone to fungus and bacteria please post 'em up...they would be interesting to read.
https://www.sciencedirect.com/science/article/pii/S0016236116310729

4. Conclusions
This study has revealed that microbial biomass in pure diesel varies with sulfur content. UHSD was the most susceptible diesel to biomass formation and the lowest biomass formation after 40 days of simulated storage was detected in ULSD. These results suggest that the removal of organosulfur compounds from diesel does not directly impact on the susceptibility of the resulting fuel to biodeterioration during storage. High-throughput sequencing analysis showed that the microbial community in the diesel system includes Firmicutes, Bacteroidetes, Actinobacteria (Bacteria) and Ascomycota (Fungi) are the most abundant microorganisms and Archaea (Euryarchaeota, Thaumarchaeota and Crenarchaeota) was also detected in all sulfur contents, but the bacterial diversity is increased with the reduction of sulfur. Infrared analyses showed possible abiotic diesel degradation in all samples; however proton nuclear magnetic resonance (1H NMR) spectroscopy revealed higher levels of branching in diesel ULSD than observed in UHSD, which may be related to the hydrotreatment process.
Seems Biomass is actually greater with higher sulfur but biodiversity is greater with low sulfer.
 
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Scooby24

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Back to OP though, this certainly does look like bio waste on the filter. Bio-Kleen describes:

"The first indication of microbial contamination is mucous-like accumulations on fuel-filters and increased requirements for fuel-filter replacement"

I would be looking at doing a shock treatment of Bio-Kleen or similar product.
 
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nokivasara

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Your car your rules... but it (common-rail) has a completely different fuel system than the previous generation (PD) and makes much higher demands on fuel purity.
As well, ULSD was in circulation before the previous generation was released, so chances are pretty good VW took that into account. :)
If you have any academic references on ULSD being more prone to fungus and bacteria please post 'em up...they would be interesting to read.
Do you have pure diesel or is it mixed with FAME or some other bio-oil? We've had diesel with sulfur levels of 2-5 ppm since the early 90's but I never heard of any bacterial growth in fuel until maybe 10-15 years ago, about the same time when we got 5% bio in our diesel.
I have never seen a black fuel filter in my cars.
I think the OP got bad fuel that already was black (from bacteria or water?) that plugged the filter, -15F is about -25? C, not that cold for winterized fuel.
 

ericbaisch

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Thanks for all the replies and suggestions. I did a shock treatment of Bio Kleen and sent the fuel supplier a letter stating that it is probable that they supplied me bad fuel. I included a photograph of my plugged filter and asked them if others purchasing fuel from the same station at the same time complained also. It will be interesting to see if they reply.
Eric
 
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