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#1
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Runaway Diesel (maybe) HELP!!!
Hey Everyone,
My 240D just tried running away on me. It has been working fine, other than the occasional time where it will not shut off with the key (about once every 30-40 times) Now I have not had a lot of time to look because this happened on my lunch break 10 minutes ago, but basically I stopped at the gas station for some snacks and turned the car off, it shut down just fine. I got back in the car, fired it up, and the RPMs began to rise. It wasn't very much at first, in fact I didnt even notice they were higher than normal so I just continued driving. I go to shift from 2nd to 3rd once out on the road and the engine starts accellerating!!!. I get to a stop light, push in the clutch and off it goes again! I tried turning it off and it actually shuts right off with the key. I pulled over to make sure the throttle was not stuck and there was no unhooked vaccum lines and all looked good. Started it back off and it started to accelerate just like before! After slamming it into 1st and 2nd to get back to work I turned off the car and coasted it into a parking spot. What would be some possible causes? I plan on doing quite a bit of reading on here tonight but in the meantime does anyone have any ideas what would cause this? Please let me know, I plan on leaving the car at work overnight as I do not feel it is safe to drive in this state.
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1983 240D 4spd 1984 190E 5spd 1987 300D (sitting for a year or two) 1989 Toyota Camry 5spd (current DD) |
#2
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Answer
Run away diesel, why does it happen?
http://www.peachparts.com/shopforum/showthread.php?t=101404 Have a great day.
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ASE Master Mechanic asemastermechanic@juno.com Prototype R&D/testing: Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician. Noise Vibration and Harshness (NVH). Dynamometer. Heat exchanger durability. HV-A/C Climate Control. Vehicle build. Fleet Durability Technical Quality Auditor. Automotive Technical Writer 1985 300SD 1983 300D 1984 190D 2003 Volvo V70 2002 Honda Civic https://www.boldegoist.com/ |
#3
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Thoroughly check the accelerator linkages first to make sure nothing is loose or disconnected and that all springs to return the linkage are functional.
Then I'd start the engine taking multiple preparations to make sure I can stop if if it runs away (something to block air intake, dikes to cut fuel line, someone in the driver's seat who can put it in gear and stall it against the tree it is tight against etc) and observe the engine to see if the accelerator linkages move as it runs away. If they don't, it's getting fuel from somewhere other than the IP/rack and you'll need to figure out where. If you have an early vacuum pump (you probably don't) it could be sucking oil thru the vacuum pump vent into the air cleaner.
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1977 300d 70k--sold 08 1985 300TD 185k+ 1984 307d 126k--sold 8/03 1985 409d 65k--sold 06 1984 300SD 315k--daughter's car 1979 300SD 122k--sold 2/11 1999 Fuso FG Expedition Camper 1993 GMC Sierra 6.5 TD 4x4 1982 Bluebird Wanderlodge CAT 3208--Sold 2/13 |
#4
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Thanks for the info guys,
whunter that is a great link, gives me a great place to start. The 240D seems to have a very simple fuel system, so this should be pretty easy to track. Oddly enough it did not just take off when I started the car, it just seemed to have a high idle when I started the vehicle and after I had been driving it would shoot right up when I put the clutch in. I may try fireing it up quickly with a buddy in the seat when I get out of work to see if it is a linkage issues. I will report back with more information after I take a look at the vehicle.
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1983 240D 4spd 1984 190E 5spd 1987 300D (sitting for a year or two) 1989 Toyota Camry 5spd (current DD) |
#5
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Had a 300td once that did the same thing. Turned out it was a broken return spring on the IP linkage.
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#6
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That's what I was thinking. Without the spring, I'm thinking the weight of the linkages can cause the rack to move. I'm also thinking that might be detectable in the accelerator pedal. Does it move down slightly as the engine revs. Also, in a pinch, the problem might be temporarily fixed by attaching a cord on the accelerator which could be pulled up to stop the engine from accelerating.
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1977 300d 70k--sold 08 1985 300TD 185k+ 1984 307d 126k--sold 8/03 1985 409d 65k--sold 06 1984 300SD 315k--daughter's car 1979 300SD 122k--sold 2/11 1999 Fuso FG Expedition Camper 1993 GMC Sierra 6.5 TD 4x4 1982 Bluebird Wanderlodge CAT 3208--Sold 2/13 |
#7
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Was there any smoke; if so what color?
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84 300D, 82 Volvo 244Gl Diesel |
#8
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Is this truly a "run away" situation? Maybe it's semantics, but this sounds like a linkage problem like others have alluded to in previous posts.
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Kevin 1978 300D 1979 240D |
#9
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Check your oil. If you're burning engine oil causing a runaway condition, your oil level will be lower than normal.
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$60 OM617 Blank Exhaust Flanges $110 OM606 Blank Exhaust Flanges No merc at the moment |
#10
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The above is why I ask if there was abnormal smoke.
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84 300D, 82 Volvo 244Gl Diesel |
#11
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When I ran virgin motor oil through my 180*F SVO system the exhaust didn't have any smoke, grey, black or blue. I don't think burning engine oil in addition to diesel would cause smoking
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$60 OM617 Blank Exhaust Flanges $110 OM606 Blank Exhaust Flanges No merc at the moment |
#12
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It won't run away in 4th gear
If it seems to want to run away, if you put it in 4th gear and let the clutch out it will certainly stop running away with a 240D. It might jerk the drive line a little, but it will certainly stop running away. Just try it once. Give it a lot of throttle and try to get the vehicle in motion in 4th gear. It won't go. This treatment on a regular basis is not good for the clutch, but it is a good way to see if you have a runaway engine condition. This will only work on a manual transmission.
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Junqueyardjim Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis 1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA 2003 Jaguar Type X, AWD. beautiful, good mileage, Mom's car, but I won't let her drive it! |
#13
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Since your car is a later 240d it does not have the vaccum pump that feeds to the intake. If oil gets through the internal diaphram seal it would cause a simular condition as yours. The output line from the vacuum pump then also is wet with engine oil inside.
This is unless someone put an earlier engine in the car. Follow the lines from the vaccum pump. Make sure they have no apparent oil inside. Your vaccum pump is still shutting off the car so you would not have a total diaphram failure. If it was total the engine might really get going and car would not turn off with the key. You might also install a temporary additional spring to the linkage just to eliminate a linkage that has not closed down. I know when this speed up is occuring you are too busy trying to get the engine shut down to examine the linkage. First just make sure it is not the earlier engine. |
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