The boat - CD27 with a 1978 Yanmar YSM8
The condition - About 3+ gallons of fuel last put in the tank about 18 months ago and used sparingly in the past, oh, 20 months or so.
The question - I have a 25 mile motor up the Tennessee River to only place that does bottom paint. Is adding a bunch of clean fresh fuel sufficient for the task at hand? In the five years I've had the boat, I don't think I've ever fully emptied the tank, so I assume I'm always diluting old fuel with new stuff.
Makes me miss my full service marina back on the Chesapeake even more.
Chris
Fuel quality question
Moderator: bobdugan
-
S/V Ethan Grey
- Posts: 166
- Joined: Apr 19th, '19, 06:52
- Location: S/V Ethan Grey - CD 30C
Re: Fuel quality question
When I bought my boat, I didn't know how old the fuel was and was reluctant to motor it to its new home. Instead, I bought a diesel fuel canister and a plastic, manual transfer pump, disconnected the main fuel inlet line at the tank and sucked all the old diesel out. I then replaced it with fresh diesel + biocide. Very good peace of mind.
-david
-david
David
S/V Ethan Grey
1981 CD 30C, Hull #199
Niceville, FL
CDSOA# 1947
S/V Ethan Grey
1981 CD 30C, Hull #199
Niceville, FL
CDSOA# 1947
Re: Fuel quality question
Diesel is not like gasoline, where the lighter molecules evaporate leaving gum and varnish. Diesel is pretty stable and should be fine after 18 months.
That said, there are two issues. 1) The key issue with old diesel, is that it condenses water, allowing algae to grow which will gum everything up. Inspect the tank interior with a flashlight for signs of water bubbles, drain the water separator and check for signs of moisture, etc. If you see any, it is time to get more serious, polish the fuel, change the filters, use bio-cide, etc. but if all is dry and clean, you should be fine. The algae appears as slimy goop in the primary filter. 2) Diesel has an unfortunate habit of forming long carbon chains which appear as black "gunk" which float about your tank until they are caught in the fuel filter or settle to the bottom, waiting to be agitated by rough seas and then clog your filter. If you see a significant amount of "crud" or black particles sitting in the bottom of your tank, it is time to polish the fuel then change the filters. If you don't see either of these problems, and the fuel filters are clean, I'd not worry about it.
-Steve
That said, there are two issues. 1) The key issue with old diesel, is that it condenses water, allowing algae to grow which will gum everything up. Inspect the tank interior with a flashlight for signs of water bubbles, drain the water separator and check for signs of moisture, etc. If you see any, it is time to get more serious, polish the fuel, change the filters, use bio-cide, etc. but if all is dry and clean, you should be fine. The algae appears as slimy goop in the primary filter. 2) Diesel has an unfortunate habit of forming long carbon chains which appear as black "gunk" which float about your tank until they are caught in the fuel filter or settle to the bottom, waiting to be agitated by rough seas and then clog your filter. If you see a significant amount of "crud" or black particles sitting in the bottom of your tank, it is time to polish the fuel then change the filters. If you don't see either of these problems, and the fuel filters are clean, I'd not worry about it.
-Steve
Re: Fuel quality question
Since you are dealing with only about 3 gallons of diesel fuel, just suck it out and recycle it. Where I live, the local city maintenance yard accepts it and heats their building with it and used motor oil. Clean the fuel tank as well as you can, making sure there is no left over water, algae, crud, or anything else in there. Once clean, replace your fuel filters and fill the tank with fresh diesel. Bleed the fuel system. Make sure the engine runs clean and smoothly before you leave the dock. Since its been sitting for a while, make sure your anchor and rode are in serviceable condition just in case. Have a good run!
Re: Fuel quality question
Serious reply - Thanks everyone, appreciated. Probably going to just siphon most of of it out, use and top it off with some fresh stuff. Whatever is in the lines and filter will get burned off and away we go.
Sarcastic reply - Anyone else with an original CD27 fuel tank see these "Just inspect the tank to see how things are going" and hurt themselves laughing?
I mean, yes, an inspection port would be delightful, however...
Sarcastic reply - Anyone else with an original CD27 fuel tank see these "Just inspect the tank to see how things are going" and hurt themselves laughing?
I mean, yes, an inspection port would be delightful, however...
Re: Fuel quality question
If you're really concerned, just zip tie a 5g jerry can full of clean new diesel in place & run your fuel line & the return into it. This will get any boat home regardless of what's going on inside the fuel tank.
That being said, when I bought my CD36 years ago, I could clearly see the fuel tank was buried under the cabin sole, and there were no access ports in the sole to inspect or clean the tank. Based on that, it was clear the tank had never been inspected or cleaned since she was built in 1985. I could see the top of the tank by looking fwd through a panel just behind the tank & I saw a round inspection port on the top of the tank that hadn't seen the light of day in decades, but there was no access to it in the cabin sole. I measured back & opened the sole up with a 6" hole saw & gained access for the first time in 30 years. It was not a pretty sight inside the tank, but I was able to remove what was left of the diesel & scrape the sludge of the bottom by hand. A small power washer filled with Simple Green got the inside of the tank really clean. There was some pitting on the bottom of the tank where water/algae sat for years - maybe I'll cut the bottom panel off the tank & weld a new bottom on some day.
The lesson learned is get in there, remove all fuel, & manually clean your tank every 5 years or so. Cut access holes if you have to. It's the only way to ensure a clean tank and good clean fuel delivery when the going gets rough.
John Ring
CD36 Tiara
P.S. Fuel polishing doesn't count. It'll never get the sludge off the bottom that churns up & blocks filters in a sea way.
That being said, when I bought my CD36 years ago, I could clearly see the fuel tank was buried under the cabin sole, and there were no access ports in the sole to inspect or clean the tank. Based on that, it was clear the tank had never been inspected or cleaned since she was built in 1985. I could see the top of the tank by looking fwd through a panel just behind the tank & I saw a round inspection port on the top of the tank that hadn't seen the light of day in decades, but there was no access to it in the cabin sole. I measured back & opened the sole up with a 6" hole saw & gained access for the first time in 30 years. It was not a pretty sight inside the tank, but I was able to remove what was left of the diesel & scrape the sludge of the bottom by hand. A small power washer filled with Simple Green got the inside of the tank really clean. There was some pitting on the bottom of the tank where water/algae sat for years - maybe I'll cut the bottom panel off the tank & weld a new bottom on some day.
The lesson learned is get in there, remove all fuel, & manually clean your tank every 5 years or so. Cut access holes if you have to. It's the only way to ensure a clean tank and good clean fuel delivery when the going gets rough.
John Ring
CD36 Tiara
P.S. Fuel polishing doesn't count. It'll never get the sludge off the bottom that churns up & blocks filters in a sea way.
Sailing involves the courage to cherish adventure and the wisdom to fear danger. Knowing where one ends, and the other begins, makes all the difference.
Re: Fuel quality question
If your fuel tank install is like my original CD 27 oem setup (I've since replaced) the tank sits partially exposed in the port locker. There is a small fuel gauge at the exposed top of the tank as well as the fuel take off and return. Remove the gauge (easy), climb into the locker (not so easy, we all have) and you can see into the tank thru that opening especially if you stick a little pen light in, and have plenty of access to easily suction the old fuel out if necessary ... most of the old aluminum tanks are pitted on the bottom inside surface making it somewhat difficult to determine if you've got slime and growth or just pitting. Good luck.
https://www.dropbox.com/s/mc78pqjkqgv5m ... s.jpg?dl=0
I agree that 18 months is not automatically a death sentence for diesel ... a tank that has never been cleaned out in 30 years - that's another story.
cheers
https://www.dropbox.com/s/mc78pqjkqgv5m ... s.jpg?dl=0
I agree that 18 months is not automatically a death sentence for diesel ... a tank that has never been cleaned out in 30 years - that's another story.
cheers
Fred Mueller
Jerezana
CD 27 Narragansett Bay
Jerezana
CD 27 Narragansett Bay
Re: Fuel quality question
All's well that ends well - 5 gals of fresh fuel went in the tank, and 4.5 hrs of motorsailing at a 5 kts delivered the boat to where it should be.
As an aside, it reassuring being in a Cape Dory when the mostly calm morning turned to a gusty 25 kts on the lake. Don't expect to have surfable following seas on the Tennessee River. Also a great test of the new ST winches - once you try them you really can't go back.
As an aside, it reassuring being in a Cape Dory when the mostly calm morning turned to a gusty 25 kts on the lake. Don't expect to have surfable following seas on the Tennessee River. Also a great test of the new ST winches - once you try them you really can't go back.