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Discussion Starter #1
I was wondering if anyone had an idea what would make a 240D feel extremely sluggish most of the time and feel extremely quick some of the times? I was thinking maybe something was seizing up but I haven't found any evidence of that. Does the vacuum system have anything to do with how fast the car accelerates??? I'm grasping at straws here...:confused:
 

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An intermittent issue can be a loose mechanical item. The 240D has little electronics in terms of vehicle drivability (most of it is for starting and charging, for accessories - but not the way the engine runs).

Check the throttle linkage bushing and linkages for binding (lube them while you're at it - do a search on how to do this).

A binding brake caliper might also cause it, when it doesn't bind all the time.
 

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Discussion Starter #6
I adjusted the valves last year. I'm not sure if they could become uncalibrated so quickly. It has a relatively new air filter and I checked/changed all the fuel filters about two months ago when I installed a new fuel supply lift pump. I was also thinking it could be the break pads but they are never hot to the touch when I check them, as for the linkage its all new. Could the muffler be clogged somehow causing a intermittent back pressure on the engine? The engine idles smoothly when it heats up but I've noticed when the car starts working really good the engine seems to idle a bit rougher and the steering wheel seems easier to turn...Power steering pump??
 

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dose the car get all the way up to temp? if not check thermostat mine was all ways sluggish because it wasent getting to running temp mine set at 60c now it runs at 90c and its a hole new car hope this helps
 

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Discussion Starter #8
Yea I was having that problem before but I changed the thermostat and it fixed the problem. I noticed the other day that the center drag link looked like it needed to be replaced but I'm not sure if that's causing the problem. My dad told me there is suppose to be some vacuum lines connected to the top of the injection pump, does anyone know anything about this or where I could see a picture of how the vacuum lines should be connected??
 

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The vacuum system plugs into a modulator valve that's mounted on the injection pump

It should have a line coming in the top and a vent line that doesn't connect to anything coming out the bottom.

Pressure in the transmission is maintained by vacuum, the modulator valve is controlled by the throttle linkage so it bleeds pressure from the system at shift points.

Thought about the fuel tank strainer?
 

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Discussion Starter #11
my car has a manual transmission :) I swear guys and or gals, I'm at a loss here. Nothing seems to be screaming out "I'm broken!" The car idles smoothly and everything but sometimes she just flies down the street and other times she is a complete snail :( So the vacuum system has nothing to do with how fast the car accelerates? I also have what looks like a small oil leak coming from the back of the engine so I was wondering if it was possible that the oil could somehow be getting on the clutch and making it slip?
 

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Discussion Starter #12
I had my fuel tank cleaned and sealed a few months ago so the tank fuel strainer was clean when I put it in. I'm nut sure how likely it would be that its getting clogged already...
 

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Just a wild guess here. Has it ever been run on waster veg. oil? The p.o. of my 240d burned wvo and there are discussions about stuck piston rings on the forums due to this. My car seems a little slower at times so I have been wondering about the valves or the rings when it happens.
 

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Discussion Starter #14
I ran the car on legit biodiesel for about three years but I must admit that someone gave me some raw vegetable oil at one point which I mixed in a 50:50 blend with diesel. I ran about 20-25gals of the stuff. That was about three years ago...
 

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We still clueless about why 240D manual tranny still have the VCV in top od the IP. However, this is a great source for this part. It's there... why? I don't know.
There is no line going to the tranny.
You can remove it and sell it on Ebay! :)

Bad compression would be constant, that intermittent behavior is kind of weird for stuck rings. They are stuck or not, that is it.

I have never user regular diesel in my car, its been more than a year running B100.
In the beginning I had the injection and fuel filters clogged every month and then 3 months and then NEVER again. Even the fuel gauge fixed itself with biodiesel.

I think that if you used SVO once long time ago and it was mixed with regular diesel its ok, but if you did that in a regular basis.... then that may that you have low compression, but it would be constant sluggishness.

And remeber what Mbeige said?


An intermittent issue can be a loose mechanical item. The 240D has little electronics in terms of vehicle drivability (most of it is for starting and charging, for accessories - but not the way the engine runs).

Check the throttle linkage bushing and linkages for binding (lube them while you're at it - do a search on how to do this).

A binding brake caliper might also cause it, when it doesn't bind all the time.
Good luck!
 

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There is a discussion about degrading rubber fuel lines, primer pump etc. with the use of biodiesel.
//www.benzworld.org/forums/w123-e-ce-d-cd-td/1223551-official-alternative-fuel-thread.html

If there is a fuel / air leak due to degraded parts, air could be sucked into the system. Could this cause a loss of power or just rough running?

Mercedessource.com sells a biodiesel friendly hand primer pump.
Heavy Duty Monark Ultimate Hand Primer Pump | MercedesSource.com
 

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There is a discussion about degrading rubber fuel lines, primer pump etc. with the use of biodiesel.
//www.benzworld.org/forums/w123-e-ce-d-cd-td/1223551-official-alternative-fuel-thread.html

If there is a fuel / air leak due to degraded parts, air could be sucked into the system. Could this cause a loss of power or just rough running?

Mercedessource.com sells a biodiesel friendly hand primer pump.
Heavy Duty Monark Ultimate Hand Primer Pump | MercedesSource.com
14 months and nothing has happened to any rubber part on my car and I use B100, 100% biodiesel. I think that as long as its coming from a regulated place and not from some dude's backyard is not going to be a problem. People like to blame any malfunctioning in a 30+years old car to biodiesel. Theoretically, natural rubber will dissolve, but I doubt I will see that happen in this car's lifetime.

When I bought the car the injection return lines were old and brittle, two of them were leaking. The car had never biodiesel in it before... so, can't blame it on bio. Although, if I pumped bio before replacing those old leaking hoses I bet people would blame it on bio.

Please don't take offense, but focus in a solution for a mechanical problem better.

I also own a 1998 VW TDI and I use B100 in it, I haven't had to repair/do anything in that car yet besides changing oil, because is not 30+ yr old car.

Monarch primer pump is not biodiesel friendly, the cheaper but better bosch has viton seals:

http://www.boschautoparts.com/dieselparts/pages/handprimers.aspx

:D
 

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Discussion Starter #19
I think I may have figured it out! y'all mentioned the vacuum control valve and it got me thinking as to how the timing on these cars is advanced. I know on my 280E that the distributor coil is advanced by vacuum. So today before I left school I connected the vcv up to the vacuum line and drove the car home. It had so much more power I couldn't believe it! I'm hoping this isn't a coincidence but it would make sense that's what its for. As for biodiesel my friend and me started the first biodiesel distribution company to sell to the public in Miami Fl. We were in business for three years and had hundreds of cars and trucks running on B100. There were only a few cars that had problems but the rest loved the stuff, my car included! I miss the smell of it. In those three years we sold 247,000 gallons of B100 to many many satisfied customers :)
 

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Glad you have it running faster! Cool story about the biodiesel. I am all for biodiesel and plan to use it in my car soon. My car was run on wvo just fine in the past (with p.o.) but I was worried about possible rubber damage with biodiesel. I will give it a try though.
 
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