Polishing Fuel Tanks

[pal1955]

I am relatively new to RVing but have 2 decades of experience on diesel boats.  Boats have vented tanks and occasionally they need to have the fuel removed to get out the water and sludge at the bottom that accumulates over time from condensation.  Is this the case with RVs?  My MH has an 80 gal tank and I am afraid to go much below a quarter tank or it may plug up my filters and bring my trip to grinding halt at the side of the road.  My MH is 10 years old with about 40K miles - so its sat a bit, I bought it in March 2017.  How far down the gage can I comfortably go down to?  So far I have left 15 gal or so but would rather not stop if I don't have to.  Thanks for all your responses.

[wolfe10]

Fuel polishing is more common in boats, but no reason it can't be done on a motorhome.  But, I would want a reason before spending the money to do it.

What do you find when you pull the primary or only fuel filter (some coaches have both primary and secondary, some only a single filter)?  Dirt? Water? Algae (black slime)?

If not, I would not spend my money to polish.

You don't mention what engine you have, but all modern diesels are "high bypass" meaning that for every gallon of fuel that goes through the system, only an ounce or two is burned, the rest being used to cool and lubricate the injections system and head with the remainder returning to the tank.  I mention that because as fuel level goes down, fuel temperature RISES as the return becomes a larger percent of fuel.  That is the reason I rarely go below 1/2 tank without a good reason-- like really cheap fuel coming up!

And, as with boats, keeping the fuel tank full when parking reduces condensation.  I also add a Biocide (Biobor JF is a common one) if storing the fuel for more than 2 months in summer or 3 months in winter.

[pal1955]

The engine is a 6.7L Duramax paired with the Allison transmission.  The rig is a 2007 Jayco Seneca 34SS.  I have the same setup in my 2008 GMC 2500 Sierra and have run almost dry routinely.  Tank capacity is only 25 gal, however.  I am about to have the Seneca serviced after 4000 miles, I'll ask about the filters.

[wolfe10]

Yes, take a throw away plastic bucket and ask the tech to deposit the old fuel filter in it.  Shake the fuel filter and tip so fuel comes out the INLET.  See what you have in terms of contamination.

[kaypsmith]

This in noway indicates that I endorse this product, but is the best example of my next  statement. In late 60's and early 70's I ran a service station, a weekly routine was to stick the fuel tanks for water, nothing but using the measuring stick and smearing paste at the bottom of the stick, the paste was a brown color and any water at the bottom of the tank would cause the paste to turn red, letting me know if any and how much water had accumulated at the bottom of each tank. The web site here http://www.diesel-fuels.com/fuel-maintenance/kolor-kut-paste.php will describe the process. Of course checking the filter is a must, but sticking as I do on my rig about twice a year will also help in deciding if a problem is about to rise. I have a filter screen in the tank on my coach but a 36 inch brass welding rod will fit through the screen and the paste will adhere to it as well as wood.

as Brett said shake the filter contents into a bucket, but I then pour the fuel into a clear canning jar and let it sit overnight, then inspect for water and other contaminants, looking for water beads at the bottom of the jar, and also black contaminates that will either float or fall to the bottom.

[manholt]

Kay.

60's and 70's we still had "Barge" Fuel...ugly stuff.

[jleamont]

Kay, I have a tube of Kolor Cut paste in my tool box, good stuff! I worked at a gas station as a teen pumping gas and we would dip the tanks weekly. Funny, that is something you don't see often anymore teens pumping gas for income, oh how the times have changed .

 

[hermanmullins]

I can agree with each of you but think how far the fuel industry has come in the last 50 years. When I worked in a SERVICE Station, We filled the tank, Cleaned the windows, and checked the oil and tire pressure. But at the same time we never filled up at a station if we saw the tanked delivering fuel. We knew that every bad thing in the storage tank would be stirred up and it needed to settle back in the bottom.

Herman

[jleamont]

I saw a product yesterday that is a thin tube sock looking device, you drop into a diesel tank (assuming you have access) and let it sit, it will accumulate water and crud, remove it and your done. It was like a water and algae magnet....I will post more on it later, I read the package briefly and I'm headed back to the store I saw it at for more parts today. Could be a cheap alternative for bad fuel in your tank.

Last year I got a bad batch of fuel at a Loves travel center, it took me 14 months and 6 primary filters to get rid of the crud it created, now I will not add fuel without an additive. Plus the added lubricity and cetane boost in my older fuel system couldn't hurt either.

[jleamont]

We are pulling salt crystals from our fuel separators at work, bi product of manufacturing that has become a real problem for us, most additives will break that down also. Ill see if I can locate and photo what we have been finding. While fuel has become better in some points, it has gotten worse in others.

[rayin]

Our MH is a 2000, with a 125G fuel tank. When I purchased it in 2013, it had been parked in a barn for 6 years. I've never had a fuel issue - yet. I do full the tank if the MH is not being used for a few months to reduce condensation.

Don't be hesitant to use your fuel below 1/4 tank for water concern, everything in the tank is shaken thoroughly as you drive today's neglected highways. The only reason I never get below 1/4 tank is the APU fuel pickup is near that point.

Diesel Kleen Clear-Diesel is advertised as a fuel & tank cleaner. I've never used this product, nor do I understand how it can perform as advertised.

[manholt]

My tank is 150 gallons, been using a quart of Kleen every other tank and have increased my engine performance and getting 6.8 mpg compared to 6.4 last year!

[rsbilledwards]

I am with Carl. I use it every tank. In my Super Duty 7.3 Ltr Ford, it is worth a 100 miles city and highway if I use it, if I do not, I loose it. I do not know what it is worth on the C 12. I also routinely run the fuel in the coach below 1/4 but then even though a 1999 built rig, it only has 16,000 miles on it and I have no contaminates to speak of showing.

On the 2001 Zanzibar I started that, using all the fuel and I did have to drain and clean the tank. It was a mess.  I would periodically  cut open the primary filter and see what was in it on the Z. It is not necessary on the Panther as it has a clear bowl.

[jleamont]

As Brett mentioned above, I have given this some thought last trip as to why my filters looked horrible in such a short time. My Fass pump moves 85 gallons an hour, just driving I'm polishing my fuel. 150 gallon tank with 134 of useable fuel space. That's a lot of fuel passing through both filters and back to the tank. After the fuel disaster last year I put additives in every tank for several reasons. Lubricant and biocides are my most important, cetane boost is another. Cheap insurance!

[obedb]

Their products have been around since the mid fifties. I use it every time that I fuel.

[wildebill308]

I run it in every tank. I like it for the cetane boost and keeping everything clean. The fact it provides  some lubricity doesn't hurt and yes I run more than the minimum mix.

Carl, try running about +50% of the recommended dosage and see what you get.

Bill

[rsbilledwards]

Ok Here is another twist since the "Cetane boost" comment has been brought up. Why add a cetane boost? We know that works and the Kleen D does what it says it does. I is easy, just pour it in

Why not add a bit of Propane as well to the mix and really improve the mileage and clean up the exhaust. Now do not get you nickers in a twist over this. First look at the current technology from PDP as they have been around now since 2000 with a vapor injection system the likes of which is now under testing in the Army and Air Force heavy haul rigs under the Federal Propane Initiative Program . Propane is metered in as a vapor above 5 PSI of boost, pre-turbo and directly into the intake air stream just before the turbo. It has several impacts,such as increasing the mileage 1 to 1.5 per gallon, foot dependent. Increase in power output, foot dependent and subsequently torque. All of this from the un-burned fuel we frequently see exiting exhausts as black smoke. It is additionally aiding older rigs in California to pass the emissions. 

The metering device is patented and is boost controlled. It is preset at the time of order for a specific application but is manually adjustable. The propane supply is electrically controlled by a relay assembly at the tank via manual controls or automated controls. If one has a JAKE it too is included in the controls.

I was at Alamo Lake last winter when an old Beaver coach came rolling in hauling a boat and a late model pickup. I went over for a chat because I thought the load was substantial for the coach. Turns out he was a retired trucker and loved fishing and you guessed it, trucking, now replaced with the coach and a fishing pole. I of course commented about the coach and the load. He just grinned and walked to the rear and showed me the propane injection system on the coach for 70 thousand trouble free miles. When he left dragging all, there was not one bit of black exhaust from the 200,000 mile rig. That was enough to make me interested. After all Propane sells for $2.50 a gallon, that is 2.5 cents per mile for an extra mile, possibly a bit more, per gallon of fuel.

I have just completed the install of the unit on the Panther. I expect propane consumption to be about a gallon per 100 miles and an increase of 1 something per gallon of fuel. The coach does not lack push from the C 12 CAT, I am looking purely for the mileage increase. I am currently averaging 8.5 MPG. Hey I like technology and have made countless changes on this coach for the pleasure it offers my lifestyle. This is the first one that might have a real physical return besides pleasure.

[hermanmullins]

Bill,

When your are finished just sit relax and have a smoke, AH.

 

Herman

[wolfe10]

Bill,

Keep us posted on the MPG before/after as well as propane consumption.  I know you keep good records.

[dickandlois]

Bill A Question. 

Thinking you have supplied the system by using the DOT tank on the coach as the supply!

Injection point - Just before the Turbo ? How does the mix affect the Air Compressor? Or is it injected into the exhaust stream. A little more then confused. LOL Like Whats new !!

Rich.

[rsbilledwards]

Rich, Brett

The air compressor is not in that link. I did think of that as well...volatile air in the air bags and air tank...no thanks!! I my case the injection point is just prior to the 90 degree boot to the fresh air turbo. The manufacturer wants it a close as possible. I did not want to , mount the orifice in the rubber boot. It does not go to the exhaust side. The idea is to have the intake pack it into the combustion chamber to enhance the burn. Yes the coach DOT tank is the supply source. In my case the tank supplies only the stove and frige.

Brett, we just did a thousand mile show and tell trip around Colorado, over 8 passes 10 thousand feet plus and averaged 8.4 MPG with the coach loaded, full fuel and water from the start. We dry camped the entire trip. Speeds were generally under 65. This is the beginning basis prior to turning on the system. The next trip will not be a strenuous as we are heading to the Pacific Northwest for the month of September. That will skew the results some until we can make the same trip again. Historically this SAFARI coach powered by the CAT C12 has had a lifetime average of 8.5 +- a bit, of course driver dependent.

 

[wolfe10]

Important point:  Many engine driven air compressors DO get their air from the engine intake manifold.

Why?  Easy: No need for a separate air filter,  Air is cleaned, compressed (by the turbo), cooled (by the CAC) before it gets to the intake manifold.  Said another way, quite a lot of the "work" in compressing is done for free by the turbo (up to 25 PSI at max boost).

SO, locate your on-engine air compressor and trace the large lines/hoses.  One will go to the air dryer, the other to the "source" of air for the system.

[rsbilledwards]

I will do that  B

[rsbilledwards]

Well so it does feed off of the intake manifold. As I think about it the air system fills if sitting for a long period or if the bags have been dumped, prior to any propane being injected to the system. The Propane is set to flow at something greater than 5 PSI of boost. At an idle No Boost. Now rolling down the highway with any kind of leak there would be that possibility or likelyhood that fueled air would be sent into the system. Thanks Brett for pointing that out.

 

B

[wolfe10]

Bill,

Air is used, not just if there is a leak, but as ride height valves adjust air to the bags and with air brakes, each time the brakes are used. Suspect in mountain driving where you are heavy into throttle, then brakes and also quite a bit of air in/out of the air bags it may be an issue.

Don't know the ramifications of propane in the air system, but might be worth exploring.