Diesel Polishing

[ColourfulOwl]

This is my first winter of owning a boat, a Beneteau Oceanis clipper 361 with a Volvo Penta 2030. Towards the end of last year, around the start of December, I filled my diesel tank to the brim, but did not add any diesel bug treatment (wasn't really aware of it being an issue until recently). Over the last few months I've been trying to get out on the boat, even in the cold, but the sporadic wind has been making that a challenge, so the engine has only been run for a few hours since.

I'm conscious that she's now been sat for a little while with no real usage, and we've had some bitterly cold weather... With more to come, that could of created some of the dreaded condensation in the tank. I'm aware diesel bug maybe an issue, and before I start to use her again for the season, I definitely want to try and polish the diesel in the tank. Racor seems to be the go to, but at £250ish for the separator it's a bit of a large pill to swallow. I have found another diesel filter that does a similar thing on Amazon from a company called Katsu which seems to have glowing reviews and is only £45. Has anyone got any experience with this brand? Any other brands people can recommend?

Also, how do you install a diesel separator? Is it simply a case of taking the existing fuel line, into the separator, and running a new fuel line to the engine? Does it need it's own pump or would the pump on the engine suffice? I'm planning on putting this towards the front of the engine bay for ease of access of emptying the bowl and replacing filters, so the fuel line would be longer. I suppose I've just answered my own question there

 

[chris-s]

About this time last year I bought one of those katsu filters along with a 12v fuel pump for polishing the fuel and cleaning the tank in our recently purchased Oceanis. We didn’t fit it permanently, instead we removed an inspection hatch from the tank and pumped out all the fuel thru the filter. Using a length of rigid copper pipe on the end we got into the corners and removed what little sludge there was. The filter unit seemed to be fine and it was always my intention to fit it permanently, just never gotten around to it.

 

[Tranona]

Before doing anything drastic suggest to access the fuel through an opening in the top of the tank such as the sender and pump out some fuel from the bottom of the tank to see if there is any water or deposits. fuel contamination does of course occur but its frequency is overrated from my experience. for example I left a boat unused for 9 years with the tank about 3/4 full. I pumped it all out before recommisioning the engine and there was no sign of any contamination. On the other hand on another boat that had been in use was checked by drrawing off some fuel and water was found. Extracted about 5l of water and much, dosed the rest of the fuel and no problems since.

 

[SaltIre]

If you have a PELA extracter Pela Pumps, Oil, Liquid Extractors, Oil Extract you can use that to sample from the bottom of your tank. If you find nice clean diesel it might put your mind at ease.

 

[ColourfulOwl]

If you have a PELA extracter Pela Pumps, Oil, Liquid Extractors, Oil Extract you can use that to sample from the bottom of your tank. If you find nice clean diesel it might put your mind at ease.

That's a good shout. The previous owner left one of these on the boat, I'll give it a go when I'm next there.

Before doing anything drastic suggest to access the fuel through an opening in the top of the tank such as the sender and pump out some fuel from the bottom of the tank to see if there is any water or deposits. fuel contamination does of course occur but its frequency is overrated from my experience. for example I left a boat unused for 9 years with the tank about 3/4 full. I pumped it all out before recommisioning the engine and there was no sign of any contamination. On the other hand on another boat that had been in use was checked by drrawing off some fuel and water was found. Extracted about 5l of water and much, dosed the rest of the fuel and no problems since.

It's going to be fun trying to get access to the fuel tank it's under the aft berth in the centerline of the boat.... suppose it could be worse lol.

Yea it's brought up a fair bit by uk sailing youtubers, which is where I'm currently getting a lot of my ideas from and has probably made me a bit paranoid about it. The challenge I have is where my boat is. There are no chandlerys anywhere near by, so I have to order everything a week in advance. Jobs that should be simple are taking nearly a month to do as I need to wait for things to turn up In a lot of case it's making more sense to order first and return if not needed

 

[Tradewinds]

The Katsu/Facor unit is good. At least the one I bought was ( for a lot less!). I used a Facet pump to circulate the fuel. Works well.

 

[Tranona]

That's a good shout. The previous owner left one of these on the boat, I'll give it a go when I'm next there.


It's going to be fun trying to get access to the fuel tank it's under the aft berth in the centerline of the boat.... suppose it could be worse lol.

Yea it's brought up a fair bit by uk sailing youtubers, which is where I'm currently getting a lot of my ideas from and has probably made me a bit paranoid about it. The challenge I have is where my boat is. There are no chandlerys anywhere near by, so I have to order everything a week in advance. Jobs that should be simple are taking nearly a month to do as I need to wait for things to turn up In a lot of case it's making more sense to order first and return if not needed

Another vote for using a Pela. As for access, my Bavarias also had tanks under the aft cabin bunk, but the sender for the gauge was fairly accessible and enough room to get the Pela tube in and move it around to reach the lowest part of the tank. Youtubers like this sort of thing as a bit of jeopardy is needed to make their stories interesting. Contaminated fuel is one of those things where the probability of it occurring is small but the consequences potentially dire both in terms of the effect on using the engine and the difficulty of removing it. So wise to be cautious and establish if you have an issue first. If so fix it and then reduce the chance of a repeat.

 

[ColourfulOwl]

Thank you all

That's made me feel a lot better about the whole situation. And you might of all saved me a few bob in the process

 

[Yngmar]

Fuel polishing is a great idea for people selling extra fuel filters and pumps. But you already have all that stuff. Your engine has two filters in series and pumps vast quantities of fuel through them and back into the tank every time it runs (just pop your fuel return hose into a jerrycan sometime and be amazed at the quantity).

Go with the pumping up of the bottom of the tank Tranona recommends and if you don't already have a nice racor (or clone) with a glass bowl on your engine and filters that can be lifted out the top, put the money there instead.

I made a copper pipe to stick down one of the spare fuel take-offs on the tank, which reached the lowest corner. Then a Mityvac hand pump with sample cup to suck up the bottom of the tank. Let it settle to see if there's any water separating out, pour the fuel through a paper coffee filter and back into the tank. Look in the filter to see if you have lots of crud. Repeat until no more crud comes up. After doing this the first time (used boat), we barely had any dirt in the filter in the following years.

 

[geem]

Fuel polishing is a great idea for people selling extra fuel filters and pumps. But you already have all that stuff. Your engine has two filters in series and pumps vast quantities of fuel through them and back into the tank every time it runs (just pop your fuel return hose into a jerrycan sometime and be amazed at the quantity).

Go with the pumping up of the bottom of the tank Tranona recommends and if you don't already have a nice racor (or clone) with a glass bowl on your engine and filters that can be lifted out the top, put the money there instead.

I made a copper pipe to stick down one of the spare fuel take-offs on the tank, which reached the lowest corner. Then a Mityvac hand pump with sample cup to suck up the bottom of the tank. Let it settle to see if there's any water separating out, pour the fuel through a paper coffee filter and back into the tank. Look in the filter to see if you have lots of crud. Repeat until no more crud comes up. After doing this the first time (used boat), we barely had any dirt in the filter in the following years.

We are fortunate that our tank is built into the hull. The bottom of the tank forms the top part of the keel. The crud and water, etc collects at the lowest point. This section is about 18 inches long and 6 inches wide. I use an access port in the main manhole to insert a length of copper twigging. This copper pipe connects to a length of clear hose, a throw away clear filter and an electric fuel pump. The fuel is returned to the tank.
If I just suck from the bottom of the tank in a single location, I only remove the crud from that location. Only by sweeping the pipe around the bottom, do I vacuum up any sticky particles. The copper pipe sucks all the rubbish off the bottom of the tank until there are no visible bits entering the fuel filtering system. It works very well ut relies entirely on being able to scavenge the whole bottom of the tank.
I have designed a few fuel polishing systems for massive diesel generator tanks for data centres. They were proper fuel polishing systems with a high performance pumps, water separators and internal pipework to create a scavenging velocity on the floor of the tank. Even with these sophisticated systems, we used to bring in a remote polishing system mounted on a fuel tanker to remove the debris that the inbuilt polishing system missed. It is very hard to remove all debris from the bottom of the tank without vacuuming every single part of it

 

[Freebee]

fuel polishing in action here :

 

[ColourfulOwl]

fuel polishing in action here :

It was this video that flagged it up as something for me to think about. A while back I also saw a video where Cadoha dealt with diesel bug that they had pretty badly. It had completely slipped my mind until I saw the Sailing Madness one

 

[AngusMcDoon]

I bought a CAV filter assembly on eBay for £17, some CAV filters for £3, a 12V pump for £8 and some 8mm pipe for a few groats, mounted it on some gash plywood, plugged it in & let it chug away all day. I stuck the pipes through the removed fuel gauge sender hole. It got some gunk out at first so I changed the filter & by the end it was all squeaky clean.

 

[Zing]

We just did what might well be a first in 24 yrs tank clean. Enormous amounts of crap were scraped off. We also had partly blocked fuel lines. That’s what motivated the cleanup. A BIG JOB it was! So yes, take your fuel tank health seriously, because if it gets as bad as it was with us, it gets bad quickly without lots of regular TLC.

 

[Freebee]

I bought a CAV filter assembly on eBay for £17, some CAV filters for £3, a 12V pump for £8 and some 8mm pipe for a few groats, mounted it on some gash plywood, plugged it in & let it chug away all day. I stuck the pipes through the removed fuel gauge sender hole. It got some gunk out at first so I changed the filter & by the end it was all squeaky clean.

and that's great if your engine is an old thumper , but modern engines with common rail injection need filtration levels better than 10 microns the cav and cav clones are nominally 30 microns that will allow a lot of stuff through that these engines cant live with.

 

[geem]

and that's great if your engine is an old thumper , but modern engines with common rail injection need filtration levels better than 10 microns the cav and cav clones are nominally 30 microns that will allow a lot of stuff through that these engines cant live with.

That's what the engine filters are for. This is cleaning the big bits of crud from the tank. Its a perfectly sensible way to clean the tank. Any super small stuff will be picked by your engine fuel filters as normal

 

[Momac]

I think the OP may be worrying unnecessarily.
Lack of use alone does not cause diesel bug issues.
A lot of people do not use diesel bug treatment and have no issues,
A lot of people don't use their engine for 5 or 6 months of the year and have no issues.
I suggest using the boat as normal when you are ready and keep an eye on the fuel filter if it has a glass bowl. Change the filter in the spring after the first run, There may also be a filter on the engine and this also may be changed.

 

[Roberto]

the cav and cav clones are nominally 30 microns

They are rated between 5 and 15u, actually the original Delphi is better than clones.

 

[ColourfulOwl]

Turns out I already have a diesel separator, I just hadn't clocked it. I have a Delphi CAV 296 with an alloy bowl. I was looking for a glass/clear bowl and completely looked passed it with it having an alloy bowl. It's pretty similar to this one, just with a 296 filter instead.

With the previous owner being a mechanical engineer before retirement he took extreme care of the engine. He installed this as one of his many upgrades. I'm actually a little glad it's a job I don't need to bumble my way through lol. Also, with it being a standard car filter it makes replacements way cheaper then racor stuff about £4 a filter vs £12ish.

 

[Yngmar]

You won't recognize the value of the Racor until you've had to change a filter at sea. There's two key differences: It's easy to open and close (the CAV bolt was making me very angry) and the fuel stays in the housing rather than spilling all over the everything. Also, with the fuel staying in, it's ready to go, no priming.