I recently went on vacation for a week to come home and find my 1983 240D 4-speed noticeably slower than normal. It was especially slow when I first drove it and it's gotten up to 45 mph, but I don't know if it can make it onto the highway. I've drove it about 20 miles since I got back and it hasn't gotten much better. Any possible explanations?

clogged filters?

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Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

Check your fuel filters.

You might also feel the brake calipers after you've driven a little while and make sure none of them are hot. Then will be warm, but if they are hot you have a caliper dragging.

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Some years of 240ds are more prone to develop linkage problems to the injection pump. Have someone press the pedal while you make sure the linkage on the injection pump is fully advancing the arm to its stop.

And check that rubber thingie on the firewall where the motion pedal linkage comes thru and connects to the linkage going to the injection pump. Might be perished enough that it's not transmitting the pedals travel to the linkage.

- Peter.

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2021 Chevrolet Spark
Formerly...
2000 GMC Sonoma
1981 240D 4spd stick. 347000 miles. Deceased Feb 14 2021
2002 Kia Rio. Worst crap on four wheels
1981 240D 4spd stick. 389000 miles.
1984 123 200
1979 116 280S
1972 Cadillac Sedan DeVille
1971 108 280S

Yes, thats a really common one with the later 240Ds

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

The thingy is called the throttle bushing. It usually brakes at the rubber damper that is part of the bushing. Some bailing wire will work for a while in a pinch.

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I'm pretty sure it's not a clogged filter. I haven't changed the filter since I got the car in april, but I think it's fine since I just converted the car to run on vegetable oil and that filter's brand new and it's slow on both. And I just checked the linkage, no problem there, pedal to injection pump transmission is fine.

Check your calipers like I stated before you may have a dragging caliper.

If you are running the veg oil through the same filter as the diesel you could still have clogged the filter. It all depends on how well you oil is filtered before you put in the car. I've clogged a VO filter in about 3000 miles.

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WVO will pull all sorts of black gunk out of your fuel system and (hopefully) deposit it in your fuel filters.

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Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

If you have recently switched to vegatable oil the solvent action could easily obstruct any new fuel filter in your system. Or even the tank filter you did not change. That is if you did not remove the fuel tank and give it a real thorough cleaning just before introduction of the vegatable oil.

This of course applies more to a single tank system. On a two tank system you could still have the same problem if the return from the injection pump went to the main tank.

From your revised description I suspect this might have occured. The car was slower after your returned because the solvent action of the vegatable oil loosened up even more old sludge in the tank with the additional time. Expect to have filter problems for awhile until all the old the sludge is eliminated. Or remove and clean the tank properly if you did not.

I think you are confusing biodiesel and veggie oil. They aren't the same thing. Biodiesel is what cleans the fuel system out. Veggie oil will as well but it does it much more slowly that biodiesel does.

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What's your VO system like? Please describe. If heating is inadequate in your VO system, you could have PHO clogging your VO filter. Cross-contamination due to innadequate purging could leave PHO in your diesel filter.

I actually drove the car today and it felt fine, so I think whatever it was smoothed out whatever settled while the car was sitting. I do have another problem with my vegetable oil system, however. I used the greasecar kit which includes a separate filter that has a knurled bolt at the bottom that one may unscrew to let out water and sediments that have settled at the bottom. It said I should check it every week. I just checked it yesterday and oil came out so I thought everything was fine and I just closed it. I was driving on the oil today when I started hitting air. It wasn't that much, it stalled and I had to pump the injection pump by hand and crank it a bit, but is that normal after you drain the filter? I don't want to wear out my starter by having to go through that every week.

Anytime you brake open the fuel system you are doing to get air in. So I wouldn't be suprised if you filled you veg filter with air when you opened the stop cock.

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