Draining 300D fuel tank - PeachParts Mercedes-Benz Forum

coachgeo · #1 12-31-2003, 06:50 PM

Am I stupid and blind? Hope so LOL.

I'm so blind I can't find a drain bolt on my 1983 300D fuel tank, and I'm so stupid I can't find a mention of it in the manuel page either. Does it have one? What is the best way to drain it if not?

I just want to start with fresh fuel in this thing and since its real low at the moment figured it would be good time to drain it.

#2 12-31-2003, 07:14 PM

I don't believe they have a drain plug as such. Loosen the fuel line and pull it off , the fuel will drain then. Acually it is best to loosen the clamp on the at the other end from the tank. Should be a short line between the tank and the hard line. Then you car direct the fuel into the big bucket you have sitting there ready.
When the fuel is drained the rest of the line comes off and the screen unscews from the tank.
As a note, most have found with the tank reading E, you may have more than 5 gals left in there. So be ready with enough containers so that you don't drown under the car.

coachgeo · #3 12-31-2003, 07:59 PM

Quote:

Originally posted by Old Deis
...
When the fuel is drained the rest of the line comes off and the screen unscews from the tank....

Thanks. Crawling under there I see three lines connected to the tanks bottom. Two are in same area and third is on opposit end. Which one is where things unscreww and opens access to screen?

coachgeo · #4 12-31-2003, 08:36 PM

Found some drawings. Think I got it figured out.

Question. There is a sealing ring (gasket) on screen housing. Is this often reusable? If not will silicon seal it? What type silicon would be best? (blue, Black??)

coachgeo · #5 12-31-2003, 11:03 PM

I see new tag lines replace all old ones too.

Dont matter I guess.

Back to regularly scheduled program:

Silicon ok?

BoostnBenz · #6 01-01-2004, 02:50 AM

The ring sometimes is but not always, it only cost about $.50 but it is just remembering to purchase it in time. I'm not a huge silicone fan, nothing to add there. I haven't looked but there is one that has a fitting on one end to unsrew with a clamp on the other. The return line however I presume is a normal fuel line clamped on both ends.

JMH · #7 01-01-2004, 09:19 AM

coachgeo,
that screen is aluminum looking and is a huge size socket... I went to my local Sears and bought a 1" drive with an adapter to 1/2" drive to get it out. WHen I pulled mine, the screen portion was clogged pretty heavily with dirt/grime/algae, etc. I would strongly recommend getting it out and cleaning it good.....yours like mine has probably never been changed in 20+ years of fuel, that's a bunch of time for stuff to accumulate. It's a piece of mind thing to me!

Good luck!

JMH

#8 01-01-2004, 10:38 AM

I'm just curious why you're draining the fuel. Unlike gasoline, diesel fuel is nothing but light oil and has an incredibly long "shelf life."

Happy New Year,

coachgeo · #9 01-01-2004, 11:13 AM

Quote:

Originally posted by LarryBible
I'm just curious why you're draining the fuel. Unlike gasoline, diesel fuel is nothing but light oil and has an incredibly long "shelf life."

Happy New Year,

Vehicle sat for some time with little in the tank. Wanted to clean it cause I have battled algae before and since it is a PITA I figured I would try to clean the screen of what might be in there.

Besides it would remove a variable and maybe make it easier to diagnose what ever might be ailing my new to me 300D.

Butttt..... even though it is 0.50 unless the indy.. has one Im stuck. No dealer here. Guess I'll just drain tank and not clean the screen yet.

Will have it put back together in an few hours or less. Will start her up with the cleaned injectors, new filters and Injector bleed lines. Hopefully the knock will be gone.

BoostnBenz · #10 01-01-2004, 11:20 AM

While I do have a stealer about 45mins from my house I nearly never use them, I just try to plan ahead on all of my parts orders. Most of the time I'm alright but when I have stuff I never expected to break I end up waiting a week for parts.

As it is rather applicable here, if a person has that black algae in the tank and they use a algaecide will some still get stuck on the strainer or does it all pretty well break up on go through the system? My lines are coated with black crap and I had a huge glob of algae in my sending unit so I guess I'll algaecide the system.

#11 01-01-2004, 03:52 PM

You didn't say how long it sat up, but I have sat up diesels for years with no fuel problems after putting back in service. If you suspect an algae problem, just dump in some biogard.

I put a Ford diesel tractor back in service this past summer that had sat for some five years. I put a fresh battery in, checked the oil and it started up after the starter rotated the engine less than one full turn. It was amazing. The tank was half empty, so I filled it up with fresh fuel and changed both fuel filters.

Just because it sat up does not mean that you necessarily have an algae, or any other fuel contamination problem.

As I said in my previous post, this stuff is not like gasoline.

Happy New Year,

coachgeo · #12 01-01-2004, 04:21 PM

old prefilter was pretty black and gunky looking. Part of why I suspected mayyyyyybe algae.

well... rear hoses at the tank looked that messing with them to drain things might cause a brittle hose to start sucking air. This would then create another variable to try to diagnose around.

Cause of this I dropped the idea and just added 5 gal to the tank. So far new OEM prefilter looks ok. but only few miles on her. I I see algae suspects I'll biocide it.

coachgeo · #13 01-01-2004, 04:21 PM

old prefilter was pretty black and gunky looking. Part of why I suspected mayyyyyybe algae.

well... rear hoses at the tank looked that messing with them to drain things might cause a brittle hose to start sucking air. This would then create another variable to try to diagnose around.

Cause of this I dropped the idea and just added 5 gal to the tank. So far new OEM style prefilter looks ok. but only few miles on her. If I see algae suspects I'll biocide it.

THANKS For all the suggestions.

BoostnBenz · #14 01-01-2004, 04:25 PM

Why not just replace the hoses then? $9ea for the "fitted fuel hose" If you feel a lack of power when the tank is almost empty then the strainer is nearly clogged and the IP is becoming starved of fuel.

coachgeo · #15 01-01-2004, 04:37 PM

Quote:

Originally posted by BoostnBenz
Why not just replace the hoses then? $9ea for the "fitted fuel hose" If you feel a lack of power when the tank is almost empty then the strainer is nearly clogged and the IP is becoming starved of fuel.

I agree about replacing. Not sure about loss of power. Have not drove it enough to know what is correct amount of power. If there was a local dealer here to go pick them up I would have done it today. Closest one is two hours away in another state.