Diesel Fuel Contamination

[lpalme]

When the Cat Service Center performed the annual engine PM on the 350 Cat engine in my 2007 Winnebago, the mechanic reported that I had deposits on the primary fuel filter inlet that indicated there is algae in the fuel tank. I looked at the filter and it had some serious sludge-like deposits on the inlet face. He said the best way to correct the problem is to remove and clean the fuel tank, a job that he estimated to be about 8 hours. The labor, plus scrapped fuel, would run about $1000. I'm considering just carrying a couple of spare fuel filters until I determine how frequently the filters are fouling.

Further research suggests that the "algae" sludge is actually fuel decomposition residues, due primarliy to aging fuel. The unit has 24,000 miles, or about 8,000 miles per year. I keep the 90 gallon tank nearly full between trips and refill at about 1/2 to 2/3 empty, usually at Flying J, Hess or other well know suppliers. Seems this problem, which just showed up this year, is happening awfully early in the life of the vehicle.

Is this a common problem? How likely is it to result in being stranded on the road side if not cleaned out of the tank? Are there "proven" additives to clean up the problem and/or stabilize the fuel to prevent sludge formation? Anyone have experience with in-line fuel conditioning devices such as Algae-X?

[wolfe10]

Welcome to the FMCA Forum.

Algae and/or water contamination in diesel is not a common problem, but it DOES happen.

You don't say where you live, but particularly if near a marine area, find a FUEL POLISHER and have them service your diesel. They come out with a high-volume pump and large filters and suck fuel off the bottom of the tank and return it to the inlet. When their filters no longer show signs of contamination, you are done. Add a kill dose of Biocide. I am not sure the labor of pulling the tank would do a significantly better job.

And some tanks have a drain plug in the bottom of the tank. But, you would still have to find a way to catch and filter/dispose of it.

Now-- how can you minimize this issue:

1. Fill up only at high-volume stations. Water can accumulate in station tanks just like in yours.

2. Keep the tank FULL, particularly when stored. If you have a 100 gallon tank and park with it half full, you have 50 gallons of air at whatever the ambient temperature and HUMIDITY you drove through. As the temperature drops at night, when the dew point is reached, it CONDENSES in the tank, sinks to below the diesel and becomes a breeding ground (actually at the water/diesel interface) for algae.

And, as the tank heats each day, it exhausts air out the vent line. And, as it cools each night, that humid night air is sucked back into the tank. Repeat 50 or more times!

3. If you are going to store the coach, add a Biocide. They are available at any marine store, as boats have the same storage issue. You will NOT find it at a truck stop, as truckers burn their fuel very quickly.

4. Modern diesel engines have HIGH BYPASS fuel systems. For every gallon of fuel that goes to the engine, only a few ounces are burned. The rest serves to lubricate and cool the head and injectors and is returned to the tank. What that means is that driving 50 miles or so after filling up will have passed a high percent of the new fuel through the filters.

SO, it is a good idea to look at the primary filter (the clear bowl) the next time you stop after filling up. If there is a problem, you can not only drain crud before it can get to the injectors, but can identify the source of the problem and potentially hold them responsible.

Brett

[jcbidd2003@gmail.com]

As a retired Volvo marine diesel mechanic, I agree with Brett, It is quite common on west coast of Canada, Had to deal with this problem many times on high speed crew boats, We would put in up to 3 large in line Racor filters with clear bowls so you can see the contamination,run boat change filters a couple of times if that did not help have the fuel polished[there are service trucks that come to you].

As Brett says only use high high volume fuel stations.

Easiest way is to try changing filters several times. Then think of options

[lpalme]

Thanks for the responses, they've been helpful.

To update my learnings and current situation:

1. Tank removal and cleaning option is more costly than I thought. After further investigation it involves about 4 hours to remove tank ($95/hr), sending tank to separate shop for cleaning ($300) and 4 hour reinstall, plus loss of fuel, so about $1500.

2. Found one fuel polisher in the Raleigh, NC, i.e. my local area. They looked at RV and found no good way to circulate and filter system due to physical set up.

3. Same company recommended shocking tank with a biocide to kill suspected biological growth and dispersant to "dissolve" resulting deposits and sludge. However, they first recommended analysis of fuel for bacterial growth (30 hours wait) and fungus (72 hours wait). Both tests were negative, suggesting sludge on my filter was not "algae", but fuel decomposition products (asphaltenes).

4. Bought some additives (Power Service Diesel Clear) to clean up tank by dispersing deposits. Have added this and will now embark on 3,000 mile trip next week, sure hope it works. Just in case, I will also carry 2 spare primary fuel filters.

5. On trip will meet up with friend from Baton Rouge, LA. He left home 2 days ago, with an 8 year old diesel MH that never had a fuel problem. Before he reached Dallas, TX he experienced severe power loss. Took the unit to a shop in Sherman, TX and computer checks showed the problem was a fuel restriction. A filter change solved the problem, at least temporarily. He went on to Santa Fe without further problems. Of note, the shop in Sherman said they have seen numerous RV's this spring with fouled fuel filters, which they attribute (based on speculation only I'm sure) to RV's sitting over the winter with ULSD fuel in them that apparently is less stable and forms decomposition products more readily than LSD used to do. I don't know if this is fact, but it's interesting that my buddy saw no problems for 8 years and now has a fouled filter, and I have a 3 year old unit that also had a fouled filter, both RV's being on an ULSD diet since 2007.

We'll travel together to the Rockies over the next month and compare experiences. On my return I'll update this note. I also plan to use a fuel stabilizer between trips to try to prevent further problems.

Any comment from others having experienced similar problems will be appreciated.

Thanks,

Larry