I'm starting to wonder about the diesel in my tank. The car has been sitting for about a year and a half now and I don't think it was fresh when the car was first parked.

I'm working on it so I can't run it dry but I could siphon it out.

I think the tank is about half full right now.

Should I drain it?

If I do, should I refill it?

The car will be sitting for another 6 months before it's ready to run.

'87 300SDL

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1987 300SDL 167k
1992 Volvo 740 140k
1990 Volvo 740 250k
1989 Volvo 240 269k

Anyone want to trade an old Volvo for an '87 300sdl?

I believe the only problem would be moisture getting in the fuel. This fuel takes a long time to break down like gasoline does.

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1977 300D Lost coolant while someone else was driving
1983 300D Can't run without oil
1985 300SD (gone but not forgotten)
1990 300TE 4matic Sold
1991 Yamaha Venture
1975 Kawsaki 250 triple
1974 Honda 200CL
1951 8N Ford
2008 Wildfire 650C

I restarted my Fintail after sitting more than 8 years. The only problem you could have is rust in the tank. Diesel fuel does not get weak or dies such as gasser fuel.
Before leaving the car for a longer periode fill up completely to avoid moistering.

Tom

If you are going to use the car in say six months just add a little diesel fuel treatment and conditioner. You could run the car for twenty minutes to make sure the pre filter remains the same color now. Before adding the treatment conditioner that is. That means no serious growth has occured in the tank. Unless the pre filter gets a really dark color it should be good to go. Diesel seems to store quite well unless it is contaminaited. It is basically just oil after all.

With a small pail, rag & screw driver, crawl under the right side of the rear axle & remove the rubber fuel line going into the tank. Fuel will flow. Catch some fuel in the pail. Replace the rubber hose. Pour pail fuel into a clear glass container & verify if there is any algae growth. This takes about 5 minutes if you drive the car on a curb so you don't have to jack up the rear end.
Now you have verified the flow through the tank strainer & algae growth.
If fuel is dirty, buy extra prefilters & top off the tank with some biodiesel or use a diesel additive with a biocide. Add diesel additive at the pump before filling.

Its fine, throw some Biobor in there and see what you get. When I first got the SD the fuel in the tank was at least 2 years old, other than algea it was fine. Maybe you got lucky, throw some biobor in there and see what shows up in your filters.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Thanks for all the help, I'll pull some fuel from the tank and see what it looks like.

I've heard that topping off the tank is a good idea because of moisture problems so I suppose I'll go ahead and do that too.

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1987 300SDL 167k
1992 Volvo 740 140k
1990 Volvo 740 250k
1989 Volvo 240 269k

Anyone want to trade an old Volvo for an '87 300sdl?

That's not the only problem you'll have. Unless the tank was full to the brim when parked, the remaining air in the tank and the moisture in the air is a perfect growing environment for algae (or something like that). And once you start driving the car again it will clog your fuel filters.

If it's really bad, you'll have to pull your tank and have it pressure cleaned. I'm speaking from first-hand experience.

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-justin

1987 300TD, 1987 300TD
2008 R32, 2000 Passat Wagon

When I finally got around to putting another engine in the 83 300CD a few months ago, it had been sitting with half a tank for a little over two years. New engine in, it fired right up. Ran the tank empty, filled up again and changed the filters.

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

Consider yourself lucky. Try doing that in a humid climate and it wouldn't happen quite like that

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-justin

1987 300TD, 1987 300TD
2008 R32, 2000 Passat Wagon

Unfortunately, the list of potential problems is a bit longer than that.

Whatever the potential problems are I'll probably uncover most of them.

__________________
1987 300SDL 167k
1992 Volvo 740 140k
1990 Volvo 740 250k
1989 Volvo 240 269k

Anyone want to trade an old Volvo for an '87 300sdl?

The trick to stopping water from getting into your fuel is to fill the tank right up to the filler neck. I have stored my SDL for 6 months at a time and the fuel remains perfectly clear, just fill that tank up to the cap and add some alge killer.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200