Diesel fuel: cloudy

[Nic n Jenny]

Hi all, first-time boat owner here...

Late last year we bought a 30' twin driveshaft cabin cruiser (Mariner 30). It has been fitted with 2 new Yanmars, each with a 200 litre fuel tank.

The boat had been sitting for 7 years and the motors had been in for 3 years (250hrs). The 200L tanks (age unknown, but has superficial looking corrosion on some surfaces) have fuel lines coming out right at the bottom of the tank (way less than ideal I would have thought!).

At the point of sale the starboard motor wouldn't start so the lines were cleaned, fuel drained (at vendor's expense).... since then we've filled up both tanks (100L each at the marina, then the rest in 20L containers).

The other day I drained a bit of fuel through (to check we had good flow and no grunge coming from the low-placement fuel lines)... port side had slightly cloudy/misty looking fuel (no water or grunge).

Can anyone think of a reason for the misty-looking diesel? Should I consider draining that tank??

[rbk]

Drain or professionally polish the tanks. Saving a bit on fuel isn’t worth a tow or wrecking an engine. I would make sure your fuel lines are A1 and in excellent shape for now and look at installing a top feed fuel line. If one of those lines break or develops a hole you might as well light the boat on fire.

[thrill]

Water dispersant additives can cause cloudiness.

[DeepFrz]

Bio-diesel? You could try treating it with a biocide and then polishing it by drawing it through a filter the pump and back to the tank. Plenty of threads on the forum that talk about fuel polishing.

http://www.cruisersforum.com/forums/...udy-41675.html

[Nic n Jenny]

Thanks — there should be no additives in the tanks, but is it possible there are residue additive traces from previous fuel? Starboard side fuel looks perfect.

Wished I'd taken a photo of the fuel now..

Planning to replace the fuel lines asap, but if it started leaking why would that be particularly disastrous?

Pulling the tanks out for modification would be a huge pain due to their size and placement so I'm kinda hesitant to do that unless really necessary. The motor runs just fine — though we've only run it for about 15 hours so far.

What would polishing the tank achieve? Draining the tank seems like a good idea... but the motor runs fine.

Sorry about all the stoopid newbie questions — thanks for your patience.

[Nic n Jenny]

Originally Posted by DeepFrz

Bio-diesel? You could try treating it with a biocide and then polishing it by drawing it through a filter the pump and back to the tank. Plenty of threads on the forum that talk about fuel polishing.

http://www.cruisersforum.com/forums/...udy-41675.html

Deepfrz, not bot bio-diesel — will start reading those threads, thanks!

[rbk]

Originally Posted by Nic n Jenny

Thanks — there should be no additives in the tanks, but is it possible there are residue additive traces from previous fuel? Starboard side fuel looks perfect.

Wished I'd taken a photo of the fuel now..

Planning to replace the fuel lines asap, but if it started leaking why would that be particularly disastrous?

Pulling the tanks out for modification would be a huge pain due to their size and placement so I'm kinda hesitant to do that unless really necessary. The motor runs just fine — though we've only run it for about 15 hours so far.

What would polishing the tank achieve? Draining the tank seems like a good idea... but the motor runs fine.

Sorry about all the stoopid newbie questions — thanks for your patience.

Bottom feed tank hose failure=200-400 L’s of diesel in the bottom of your boat. If your bilge pump kicks in (no sensor) you’ll have an environmental cleanup bill from your harbor. Either way you’ll never get the smell out. Polishing will remove any water and particulate leaving clean fuel: depending on your location draining the ranks may be quicker and cheaper but polishing will be less hassle.

[Uncle Bob]

Originally Posted by Nic n Jenny

Thanks — there should be no additives in the tanks, but is it possible there are residue additive traces from previous fuel? Starboard side fuel looks perfect.

Wished I'd taken a photo of the fuel now..

Planning to replace the fuel lines asap, but if it started leaking why would that be particularly disastrous?

Pulling the tanks out for modification would be a huge pain due to their size and placement so I'm kinda hesitant to do that unless really necessary. The motor runs just fine — though we've only run it for about 15 hours so far.

What would polishing the tank achieve? Draining the tank seems like a good idea... but the motor runs fine.

Sorry about all the stoopid newbie questions — thanks for your patience.

Hi, no such thing as stupid questions. I have a motorsailer that had similar fuel problems when purchased, have since discovered that polishing the fuel does work well at removing any crud and water from the mix plus I use a product sold as fuel doctor at the rate of 1ml per litre of fuel. Has worked well for years now and will continue to use it.
I see that you are on the Clyde river, enjoy!!

[Nic n Jenny]

Thanks all, great info!

Still reading about the polishing thing, can you recommend any kits to purchase?

Clyde River is amazing! Looking forward to the ocean once all this fuel business is remedied

[Uncle Bob]

Originally Posted by Nic n Jenny

Thanks all, great info!

Still reading about the polishing thing, can you recommend any kits to purchase?

Clyde River is amazing! Looking forward to the ocean once all this fuel business is remedied

Plenty of info on here if you search for it using the google custom search rather than the sites regular search.
When fuel is sorted and you venture further there is good old Jervis Bay just to the north.

[rbk]

Originally Posted by Nic n Jenny

Thanks all, great info!

Still reading about the polishing thing, can you recommend any kits to purchase?

Clyde River is amazing! Looking forward to the ocean once all this fuel business is remedied

Best to have a local company come out and do it if it’s an option. You can purchase/install/build your own but will cost more initially. Draining maybe your only option if no companies exist near you.

[rbk]

Also if you don’t already have an additional filter (outside your engine mounted one) ensure you install one or two. They’re not cheap but neither are new engines. Racors are the standard juat make sure the filter can handle your flow rates.

[Lepke]

If you have a Racor like primary filter that separates water, installing a 2 micron filter and an extra fuel pump will make a pretty good polishing system. The pump can be anywhere after the primary and plumbed back to the tank. Add a good biocide/stabilizer and run the pump until the tank volume has been turned over several times.

Once your tanks are clean, and you buy clean fuel, you can continue to run a 2 micron primary if you like. I have for years.

A lot of diesel boats have bottom tank supply lines. It's not gasoline. Diesel ignition is about 500°F. In the military, I ran a boat, full of holes, with 2' of diesel in the bilge for about 3 hours.
And you can get the diesel smell out.