1983 om617 shutoff question
 

So, if you have a high mileage (unknown but 400k+) om617 and most of the time it shuts off right away with the key, but occasionally it wouldn't shut off right away, and at first it would shut off by itself after 30 seconds or so or when you press the stop lever, but now sometimes you can press the stop lever all the way and it slows down but keeps running, then if you press the stop lever again it will shut off is there any way to fix it? It has no problems probably 95% of the time so there is not really any way to test anything, but does anyone know what could cause that? I can't really work on a diesel beyond stuff like changing fuel filters and stuff that's no different from a gas engine so im not sure if I should try to get rid of it before it gets worse or not.

You have a vacuum leak somewhere which is causing the engine not to shut off with a key. Diagnosis usually requires a Mity Vac. The fact that it's intermittent suggests that the leak may be in the climate control system since various vacuum pods are activated at different settings. You can perform a simple (and not completely reliable) test by pushing the far right button on the climate control panel and seeing if the problem goes away. If it does, the leak is probably in the climate control system.

If you are pressing the stop lever at the IP and it still isn't stopping I reckon you need to make sure that the throttle linkage isn't restricting the movement (of the stop lever).

It seems to be completely unrelated to changing settings on the climate control, but as far as I can tell the climate control doesn't function at all anyway. The stop lever seems to move as far as it's supposed to, the only sticky part in the throttle linkage is the gas pedal, it is a new redesigned one from the dealer so it sticks enough the car idles a little high unless you pull it back up with your foot, but I'm not comfortable using an original one after the one on the car when I got it snapped off and jammed the throttle wide open, it just seems too dangerous to me. I dont think that is effecting the stop lever moving though.

Maybe post what chassis this is also? Is this a 300d or 300sd or 300td or ???

I actually JUST barely started having problems with my ignition (on an 85 SD), so I will be paying close attention to replies. Sometimes when I turn the key the engine doesn't stop. I stop it by putting the key back in the ignition, turn it right to "accessory", then left again but slowly this time. I haven't had to use the stop lever yet.

Its a w126.

So am I the only one this has ever happened to?

I've replaced an accelerator pedal on a 126. I had no problems with high idle. That could be your issue right there. Fix that problem and report back.
You can test your vacuum shut off diaphragm by replacing the brown line with a piece of vacuum hose and sucking on it with the engine running. If the engine shuts off and you don't get a mouthful of oil, your shut off valve is working correctly and the vacuum problem is elsewhere.
It's not an unusual problem.

Using kerry`s vac tube suction works, but use a clear tubing so if there is oil you will see it coming up the tube.
Getting oil in the tube would indicate that the vac shut off valve diaphram has ruptured, and the valve should be replaced.

Have you lubed the linkage ball and sockets? if they are dry and rusty, that will cause your sticky peddle problem, or the lever behind the IP not moving it`s full travel.


Charlie

I'm still stuck thinking about the linkage I'm afraid - I think Charlie is on the right track.

I haven't discovered too much about injector pumps yet but I know it is all mechanical in the end. The vacuum idea could indeed be part of the trouble but to the best of my knowledge (so far) the stop button is a physical connection to the rod that stops all fuel flow to the injectors. If you push the stop button and the fuel still goes through to the injectors then there's something seriously wrong.

Do you know if the IP has been "tuned" in some way - ALDA messed with?

I can't. I'm not willing to risk getting in an accident (or possibly blowing the engine) by using an old accelerator pedal, and the new ones have been changed so they won't break and jam the throttle wide open, but at least on mine it sticks down slightly when I take my foot off the accelerator. I don't think there has been anything changed on the injection pump, although one of the adjustment stop screws is missing because the tab is broken off the back of the pump. It runs fine though, except for sometimes shaking at idle, but it even idles smooth most of the time. I have been driving it for more than a year and it still runs about the same as when I got it.

There's something wrong with either the pedal or the installation if it's not letting the engine idle. I put a new pedal on a 126 less than a year ago and it worked fine.

Was it a new pedal from the dealer? Its possible that the rod attached to the car that the pedal moves is damaged, other than that I don't know what the problem might be. The old style pedals have a cheap plastic double hinge which just works by bending the plastic back and forth until the pedal breaks off of the part that attaches to the rod and jams the throttle wide open. Especially with the problem I mentioned in the first post I dont want that to happen to me again. The new pedal (same part number) has been redesigned to just slide back and forth on the shaft. It was very difficult to slide on, and it mostly works ok except for sticking down just enough to make it idle a little high.

But, as far as my original question, so I should use the method mentioned to check the shutoff valve by applying vacuum to a clear hose and see if the engine shuts off and if it sucks any oil into the hose, and if thats not the problem then there is probably an internal problem with the injection pump? If that's the case it will be for sale, its still a nice car otherwise but I don't want to spend the money to buy a rebuilt pump (and pay to have it installed too since I don't know how).

Travis,
Have you lubed the linkage ball and sockets? if they are dry and rusty, that will cause your sticky peddle problem, or the lever behind the IP not moving it`s full travel.


Don`t condemn the IP as your problem they usually last the life of the eng or more.

Charlie

Got my pedal from an online parts source. Can't remember exactly how it attached but I do know that when the original failed, it could have jammed the linkage. I seriously doubt there's any internal problem in the IP.