I got this car for a good price because of a fuel leak. Fixed all the leaks, new battery, new glow plugs, wouldn't start. I gave up and towed it to a shop by my house. They have a really good diesel guy and they do a lot of work on these old things.

Turns out the PO took the whole fuel pump off and put it back on 50 degrees off on the timing. They cleaned, calibrated, timed. He calls me and says that it's ready, but very slow. We blame it on the old fuel because it's been sitting at least two years. They tell me the compression is good, the injectors are good, the timing chain is good.

I topped it off and found a hole in the tank. Fixed the hole and replaced the screen. All the filters are new. Fuel is new. Still no power.

I can't even drive it to work because of an incline. 3rd gear floored held steady at 50. My 81 240D maintained 70 no problem. It drives fine and has good pick up on the free way, but the low end of gears is barely moving. It's hard just driving it around the neighborhood.

I looked at the valves yesterday, and only a couple were a little tight. Engine starts easy, sounds great, but takes a few seconds to idle smooth when I adjust the choke or throttle to a different speed. It feels like a fuel problem, but I can't think of what it might be.

Tires are under inflated, aftermarket K&N air filter that I've cleaned but looking to replace, and in dire need of new shocks. Im outta ideas. Any thoughts?

I forgot to mention, the throttle linkage looks good, but I feel like I should have more travel in the arm on the fuel pump. I have no experience with the W115, so I don't know what normal is.

I feel like my experience with the W123 has made me dangerous with this one. Like I know what I'm doing when I don't actually have any idea.

Do you observe the linkage on the injection pump advancing to the stop? Have someone step on the pedal for you to observe. Too typical an issue to ignore the possibility. Although I would have thought your mechanic should have caught it.

Section 07.1 of the Engine Manual in the FSM for your 75 240D should be helpful.
Mercedes-Benz Model 114/115

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

The lever on the pump has more travel in it, but I've got the linkage as short as I can get it. I've got full travel at the intake though. Can the lever on the pump be adjusted, or just the linkage?

And Alec, that link is not working for me. I'll try on another computer in case it's just my phone.

You probably have some stuff missing in your linkage allowing more slop. The key element is hitting the stop on the injection pump.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

My locks aren't working either. I've been putting that off until I sort the engine, but could a vacuum leak in the pump cause a driving issue? The line that splits off from the booster has a cracked plastic valve so I assumed that's where my leak is.

Engine performance is not related to vacuum issues. If you even had no vaccum system at all car would still run fine other than you would be unable to shut it off and have very poor brakes.

Again with someone pressing the pedal down the lever on the injection pump must reach the stop. This is just so common it has to always be checked.

I actually purchased a 240d that the owner had driven this way since he acquired it many years prior to myself. I fixed it in about five minutes when I was picking up the car. The change blew him totally away. I estimate he drove the 240d at about half power for at least several years.. To me that is a challenge I would not personally want.

The pump injection pump lever in the system is not really adjustable. You have to get the linkage in shape so that the injection pump lever hits the end stop with the pedal. Really that is job #1 and very common.

If the previous owner had removed the injection pump and re-installed it incorrectly, there is also a pretty good chance that the linkage was re-installed incorrectly.

The shop ultimately reinstalled the pump. We blamed the performance on old fuel and left it at that. The linkage looks good, but most of the pictures I've seen show the linkage over the valve cover bent. Mine was so straight it was rubbing so I bent the heck out of it last night.

I now have full travel, but my idle speed is shot so I'll have to tinker with that tonight. Can't get enough air in to idle.

The car still surges like its searching for the idle, but at the moment, I'm blaming that on the intake valve. Hopefully I can get it sorted.

Were you able to open the FSM link from Post #4?

Adjusting the linkage is Job # 30-300. http://eva2.homeip.net/W115/program/Engine/615/30-300.pdf

Additionally, part of the problem may be a tear in the diaphragm of the pneumatic governor
Job # 07-215. http://eva2.homeip.net/W115/program/Engine/615/07-215.pdf

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

I was able to open it on my work pc. Just not on my phone. Insanely helpful and much appreciated.

I've always been good at figuring out how things work so I never put much thought into the FSMs. Got me thirsting for knowledge now!

I think my engine surging at idle might be due to a tear in the diaphragm of the pneumatic governor. The shop said they had the pump apart so I'll ask if they inspected it.

Its got some silly aftermarket K&N air filter and I'm not familiar with these pumps yet. If I convert the intake manifold and filter to the W123 style, would I need to replace the whole fuel pump? Would it be worth trying, what with the throttle linkages so diferent? I may be rebuilding the engine on my 123 soon so I could 'borrow' all the parts I need to do it.

After more research, a tear should cause faster running. Maybe a worn spring?

Me thinks you need to do 1 thing at a time.The throttle linkages are set to a specific length that can be measured. The 1st thing I do with a new diesel especially one that's got questionable fuel is dump some Startron into the tank, change the filters and adjust the valves. Plug any vacuum lines except those that go to the engine, transmission and engine kill switch. This car may be old enough that vacuum is a non-issue. Check the FSM.

Please post pics of the car. We want to see.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.