380: cleaning fuel tanks

[team karst]

Since the manual calls for regular (5 year) cleaning, how are folks doing this?
THese are just 25 gallon tanks, and it seems reasonable to me to do this involving the fuel level sender hole.
Question: is the seal here the typical US standard 5 screw attach? Or, some more unique metric based item?
For the actual "cleaning", I'm thinking of a small fuel pump attached to a stiff plastic tube and run this around the corners/bottom of the tank. Any words of wisdom out there? TIA.

[MicHughV]

Cleaning a diesel fuel tank is no simple matter, you really need an "access" hole to get inside the tank, as the bottom and lower sides of the tank will likely be covered in black slime.

There are threads on this CF that cover this topic.

[hugosalt]

Agree with MicHugh as to installing an access panel.
Nasties need to be cleaned out often more than a vacuuming needed.
Installing an access panel straight forward/easy job.
And you will be less likely to defer job when time comes as access will be easy.
Seabuilt seems to be the go to unit but at (think?? $200. plus) I installed a
Boyd Welding panel . cost $40. Boyd is out of Florida and main business is custom fuel tanks for automotive world.

[team karst]

Good answers. Thanks. I suppose im not done with questions. I did read the seabuilt instructions.
Cryptic warnings about flammable liquids, but only mentioned gasoline specifically. So, does the 8” hole operation demand an MT tank? Also, i will suppose the cleaning operation is best done with low liquid quantity in tank?

[davil]

Originally Posted by team karst

Since the manual calls for regular (5 year) cleaning, how are folks doing this?
THese are just 25 gallon tanks, and it seems reasonable to me to do this involving the fuel level sender hole.
Question: is the seal here the typical US standard 5 screw attach? Or, some more unique metric based item?
For the actual "cleaning", I'm thinking of a small fuel pump attached to a stiff plastic tube and run this around the corners/bottom of the tank. Any words of wisdom out there? TIA.

===========================
there two ways to do it
the right ways as hugo salt and MicHughV described and then my way.
my way
I use the sender unit as an access point, wish had a real port, someday?

have a 20 gallons and this year took advantage of been low on fuel and pumped all out into 3 jugs I have.
I use a camera like one of this

NIDAGE Wireless Endoscope for Automotive Inspection Semi-Rigid Flexible Waterproof 5.5MM WiFi Borescope Camera Compatible Android and iOS Smartphones, iPhone, iPad (4.92FT)

Use a copper tube the length of the tank plus to scrub the bottom, since I am fanatic about filtering fuel before going into the tank plus polishing every so often there was not much, just a few spots of black algae

took me about a couple of hours and filter the fuel back, very little sediment.

You might like to check the bottom and have an idea?
good luck

[davil]

if you decide to take a look at the tank when removing the little screws please, take one by one out of the way, my first time one rolled on the top of the tank and fell through between tank and bulkhead.
cannot remember if they are mm, but in any case, if you do it, go to the hardware store, get a few extra and taped them to the tank as spears.

[Marathon1150]

We have done this through the fuel level sender hole a couple of times. The second to last time did not go well, at least partially because I had someone do it for me. Not long afterwards, we encountered a major problem with the Racor 500 filter clogging - we thought it was the filters, and it partially was. The bigger problem was the paper towel fibres trapped in the water blocking device on the filter. See photos. It is amazing that any fuel managed to make its way through the Racor. We have a vacuum gauge downstream from the Racor and as soon as it hit red, the engine would stop. Changing the filter helped and we could get another 5-8 hours of run time out of the engine before it would stop again. It was later that we discovered the blocked check valve.

We cleaned the tank again after the above incident(s) when we reached Tahiti, by taking out all of the fuel, using a pump to pump clean fuel back into the tank via the sender hole, and doing our best to ensure that the bottom of the tank was as clean as possible using this mechanism.

Learning: a proper access panel would make a world of difference and is on the "to do" list.

The sender hole is a very poor substitute for a proper access panel.

[gonesail]

the Seabuilt access panels are nice and would be easy to retrofit into an aluminum fuel tank. but if your tank is only 5 years old .. you should take a look at it .. while empty .. thru the sender hole. it may not need cleaning

[Cheechako]

Originally Posted by team karst

Since the manual calls for regular (5 year) cleaning, how are folks doing this?
THese are just 25 gallon tanks, and it seems reasonable to me to do this involving the fuel level sender hole.
Question: is the seal here the typical US standard 5 screw attach? Or, some more unique metric based item?
For the actual "cleaning", I'm thinking of a small fuel pump attached to a stiff plastic tube and run this around the corners/bottom of the tank. Any words of wisdom out there? TIA.

You can do it through that fuel gauge sender hole. It's a small tank. To be productive, you need some strong flow if you want to wash out the tank. Commercial cleaners have two large filters and a pump that flows like a garden hose out of about a 3/8" fitting. Visualizing I would say the pump motor was probably 1/2 HP.

OTOH if you just want to clean your fuel, a lower flow would work.
Ebay and others sell spin on filter mounts for like $20-25. There are large filters cheap for those. You can just wait until the fuel flows clear going back into the tank and dispose of the spin on.

Some people here have a small Walbro or etc pump that just continually and slowly cleans the fuel whenever the boat is running.

I think the commercial guys want the tank about 1/3 empty

[MicHughV]

Some years ago I swapped engines on my boat. As part of this endeavor, I also removed the original diesel tank, as I planned to replace that as well.

Once the old tank was out, on a whim, I took the access cover off to take a peek inside.
That tank was maybe 7-8 years old.

Lordy, lordy, lordy...I did not expect to see what I saw. The bottom and lower sides, about 3-4" up the sides, was covered in black gooey slime, about 1/4" thick. I have since researched the cause of this, but regardless, this is quite a common problem for a diesel fuel tank.

I don't see how the inside of a tank can be cleaned thru' the fuel pickup hole alone, as access is severely limited.

The tank (like mine) may also have baffles inside to prevent fuel from slopping around, which is another reason why the fuel pickup hole will not work.

I think all the fuel needs to be removed to clean this goop out of the tank, as you don't want it mixing with any residue fuel.

My fuel pick up line extended down to about 1 1/2" from the bottom of the tank, pretty darn close to this goop.

There's pretty much no way around this. You need decent access to all corners of the tank.

I have no idea how one would go about cleaning this. Pressure washing maybe ?? A long bristle brush ??....various solvents...yards of paper towels....heavy rubber gloves..it would likely be quite a project.

It would be a long arduous, filthy, dirty project, no doubt, but once done, you'll be happy you did it.

I do know that there are companies around that specialize in this type of cleaning, an internet search will likely turn up something.

From my point of view, I'd get a pro to do it, no two ways about it.

[Uncle Bob]

A question to the brains trust, how often do diesel powered road vehicles require their fuel tanks to be opened and cleaned, excluding any simple polishing of the fuel therein?

[davil]

My hunch is long haul trucks have a constant work of their engines constantly refueling where the typical sailboat has a very low turnover of fresh fuel, many boats seating with half full tanks for almost a season, and high possibility of condensation, the fuel needs that condensation to create the water for algae growth.
Just a thought

[MicHughV]

Diesel fuel in trucks tend to get used up in a single day, or maybe every few days, and then get filled with fresh fuel.

Diesel fuel in a boat diesel tank may be in there for months...years???...

I think condensation inside a boat fuel tank, the vent line to the tank (salt air) are all factors.

Diesel fuel for trucks generally come from Fuel stop places, where it is presumed the main tank also see fresh fuel on a regular basis.

I've been to places, where the diesel fuel arrives inside rusty 45 gallon drums on the back of a truck, and no telling what is inside there.

There is your difference.

[davil]

[QUOTE=MicHughV;3538184

I've been to places, where the diesel fuel arrives inside rusty 45 gallon drums on the back of a truck, and no telling what is inside there.

There is your difference.[/QUOTE]
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In Nicaragua local fisherman sold me fuel from a rusted huge no lid barrel using buckets to transfer to my jugs.

[davil]

other point of entry for seawater is reported due to aging o rings on the deck plate.
After reading about it been more attentive and replaced the one came with the boat,was dry.