Hi there.
Over the past few days my 1983 300D has been sluggish while going uphill.
It would occasionally "flatten out" (no acceleration) as I was driving it.

Tonight I drove the car about 10 miles...
As I left my home it did the same thing. By the end of my trip (on my way home) the car would barely even move. I would have it floored and it would barely be at an idle.
It would do a little better (but not much) in park and neutral. By a "little better" I mean that it would chug for 4-5 seconds then rev up. Other times while parked I would give it gas and it would just chug.
When I let it sit at idle it will idle fine at times...then at other times it will just die.

My inline (pre) filter is very black but I am able to blow air though it (I do not know if that matters or not). I have yet to open the secondary (main filter) as I do not think there is a way to visually check it.

Both of the filters were changed about a year and a half ago.
There are only about 10,000 miles on them.
Whether they are the problem or not I will be replacing them tomorrow.

I use petroleum diesel and I do not suspect algae to be the problem.

I guess my question is:
If it is indeed the filter(s)... Is it normal for the problem to develop so quickly (over 5-6 days time)?

Does anyone believe that it is the filter(s)?

Thanks you for your time and help.

I would suggest the filters first, petroleum diesel also has algae. filters should get replaced every 15K at most. shine a light from under the clear pre filter and see if it is contaminated.

Did you fill up at a place other than your usual place or an off-the-road store that doesn't do a lot of volume in diesel sales? Its very possible you've picked up a bad batch of fuel. I'd start with both filters and work from there. If that doesn't fix it, I'd move on to checking the tank strainer for an infestation but definately start with the easiest things first.

__________________
Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo

I gotta say changing your filters, especially your primary (inline) depends on you and your car's history and how you drive it, not just on your mileage. I have only owned mine for ~1500 miles, replaced both filters right off and car ran great, just recently ran the tank near dry to where it hardly ran due to sucking air, and now, all of a sudden, I've got a ton of dark crud in my primary (inline) filter and the idle is lower, the power is a little lacking off the line and cold start-ups are a bear. Personally, if you have a clear-type primary filter and are seeing black stuff in there then I'd say change that bugger and see what happens. If not improved then go the extra $$ and replace the spin-on. On an off note, I was really shocked when I tried to start my '83 300SD today, at 48^F with tank gauge near R, with some newly noticed crud in a new primary filter, no glow plug light which is normal for me....it almost refused to fire. When it did it loped and got worse with added throttle. It finally chilled out at 700 with a little pedal but croaked when throttle was let off...not usual behavoir. I added the 1 gal of diesel I had laying about and that seemed to make her happy. Drove her to the station for 10 gallons and she's fine now but jeez...what a temper. Now I just gotta wonder what is in that filter...algae or just crud...hmmmm

__________________
1983 300SD... 269,000 miles, nearly 2,500 on my B-100, Faded Grey, Ugly in an elegant sort of way...Duh-Benz


If any of this has been a blasphemy to you, then good, because it's been a blast for me to...A.Whitney Brown

Just a possibility....

Change the rubber fuel hose that connects the metal fuel line from the tank to the plastic in-line filter. I wont go into boring details, but I recently had a week long fiasco that ended up costing me $500, and the problem ultimately was fixed by replacing this hose. My car behaved as you describe, and it was due to this line which was hardened (probably original) with cracks in the rubber where it connects to the inline filter. When I clamped it onto the filter, it distorted the cracks, allowing air to enter.

Get regular Goodyear black braided fuel line at your local auto zone.

There are many other causes of the symptoms you describe:

- Clogged fuel filters, clogged tank screen, algae in tank - sounds like you have some crud in the inline filter..

- adjust valves...valves typically get tight over time...this prevents valves from closing causing you to lose compression, noticed especially under load.

- bad injector(s) -take them to a shop where they can test spray pattern and release pressure. Clean out where the injectors screw in and seat, and install new heat shield washers.

- air in fuel lines - make sure all connections of the hard fuel lines from IP to injectors are tight. Check entire length of hard fuel lines back to the tank for leaks. While you are replacing the rubber hose (above), check and/or replace the two rubber lines that connect the hard deliver & return lines to the tank

- clogged delivery valves - these are located on the injection pump, and the "spider" fuel lines connect directly to them. Inside there is a spring, and a little moving metal piece which must slide freely inside the housing. Remove them, clean, reassemble, and replace the copper crush washers. IMPORTANT...do not remove the apparatus held in place with two nuts (one for each fuel line where it connects to the IP)...the delivery valves are on top of these and just unscrew.

These are just a few things...there may be other causes related to vacuum, egr, banjo bolt & line on intake manifold, etc..

good luck,

Mark

__________________
1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)

There are many things that can cause the symptoms you mention. I would work through the basics and then go to more advanced items.

Maybe some of the pictorials will help you.

http://dieselgiant.com/mercedes_diesel_maintenance_tips.htm

Ask if you dont understand anything.

__________________
1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

1984 300 D Turbo
Do A Diesel Purge Go From Purge Can To Input Prefilter And Return Line To Diesel Can Run Engine And You Will See The Dirt In Prefilter Replace 2 Ea. Filters Done Diy
VALVE STEM SEAL KIT
MB# 617 050 00 67


TURBO SEALS, 2-6 HRS DIY

Well I changed out both filters...
The car would'nt start.

Staring at a can of diesel purge I thought "if I run out of this can and the car does'nt start it will rull out the fuel tank screen.
The car started right up.

I then drove it for about a half mile and it died as I was driving it.
I pulled over and tried to hand prime the fuel system...to no avail.

Then I realized what the problem was: I was simply out of fuel!!!
Luckily I was next to a coworkers house and he brought me fuel (we run heavy equipment ...so we all carry 100gals of diesel on our worktrucks).

In the end: My fuel gauge is broken hahahaha!!

Car runs great though now with new filters and a fresh purge.

Thanks for all the help guys.

I'm happy it's something so simple.

Can anyone point me to a good walkthough of replacing/cleaning the float for the fuel gauge?

You did not need to change the filters. This is a German car not a GM. I did not change any of my fuel filters until 150,000. After I changed the filters I needed to replace the primer pump.

__________________
2009 CLS550 55,000
2004 ML350 144,000
2004 X5 95,000
2002 X5 165,000
1996 320S 155,000 (sold)
1991 190E 192,000 (sold)
1989 300SE 160,00 (sold)
1984 300D 210,000 owned since 85, (sold)
1984 300SD 160,000 (sold)

That's a good one. Got any more?

Haha.
My 300D runs so much better for like 2 months after I change the filters.

I swear when I bought the car the filters had never been changed (@226,000 miles).
It ran like crap.
Spent $15 and it ran like a different car.

The quality of the fuel that gets filtered has nothing to do with the auto maker. Dirty fuel will foul any fuel filter Dodge, Honda, MB or Chevy. Dirty fuel does not descriminate and it does not negociate.

__________________
1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

So why does GM and Ford tell you to change the filters so often in there diesels? Ford wants the filter changed at 5000.

__________________
2009 CLS550 55,000
2004 ML350 144,000
2004 X5 95,000
2002 X5 165,000
1996 320S 155,000 (sold)
1991 190E 192,000 (sold)
1989 300SE 160,00 (sold)
1984 300D 210,000 owned since 85, (sold)
1984 300SD 160,000 (sold)

i changed my filters after god knows how long its been and now it revs up faster and accelerates so much better now i can see how far i have to turn down the alda..

Maybe they are affected more by fuel starvation due to clogged filters. The people who make the cars definately don't have a say-so in where you fill up, or any control over the algae that may be living in said fuel

__________________
Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo