Hey All,
1983 240D. About a week ago i was starting to get the old engine keeps running when turned off. no problem, i figured next week i'd get the new cut off valve. THEN things got weird. after the car sits for 1/2 hour, my vacuum locks don't work. As soon as i start the engine though, they do. so it seems to take the vacuum system about a 1/2 hour to bleed down. I have no problem starting the car at luncj time and the end of the day when i leave work, but when i leave it over night, it is almost impossible to start. taking about 2 minutes of turning over. i live in florida and it's in the upper 60's in the morning. i have in the past started her without more than 2 seconds worth of glow plug heat. when she does start, big puffs of dark smoke for about 5 seconds then everything is fine. if i immediatley turn her off, she'll start again.
do you think this is related to my vacuum leak? do you need vacuum for the car to start when cold for some reason? i was thinking maybe the amount of time it takes to start is how long the vacuum pumps takes to build up the reservoir some, but that would be contradicted byb the fact that she starts fine in the afternoon and at the end of my work day.(5pm).
maybe the vacuum leak is just coincidence with bad glow plug relay or something else? i know a vacuum line goes to the ignition, but i'm not really sure why.
any ideas? i have a vacuum gauge and might vac pump.

Thanks,

dale

Dale,

You said a vacuum line goes to the ignition. What "ignition" does a Diesel have? Do U mean the key switch?

A vacuum line goes to the key switch because that is what stops the engine when U turn off the key. There is a shut off diaphram on the IP. When the key switch is turned off, vacuum is applied to that diaphram and the fuel is shut off and the engine stops running.

So with no vacuum, the fuel couldn't be shut off so no vacuum will not have an effect on engine starting. I have a 300SD that the vacuum pump quit working and it doesn't affect engine operation or starting at all. Someplace U have a vacuum leak but that is another problem separate from the hard starting.

I would check the GP. If they are not working, the engine will start cold but a lot of cranking will be required.

Do a search for cabin light and you should find an easy way to check the GP.

What type of GP do U have: Series, parallel, automatic with GP controller or manual operation?

P E H

I cannot think of any reason that a lose of vacuum would cause hard starting. I know I have started my car with no vacuum in the tank for various reasons. I would check glow plugs, look for air in fuel lines, etc.

yes, yes, key switch. sorry at the age of 40, where the key goes on the dash will always be an ignition switch. i guess the glow plugs is wher i go next. it just seemed REALLY coincidental that the problems were simultaneous. i'm trying to learn as much as i can, having just gotten this car in november. i'm loving it, but it's got a slightly steep learning curve what with all the vacuum controls.
good news so far, thanks to this site i've fixed the odometer and the clock, so i'll just ride the inertia of those victories and perservere into the realm of the engine oh, and i guess fix the vacuum leak too.
thanks for the replies. you guys rock.

dale

Just wonder if it's possible if the shutoff device has ruptured internally and is kind of floating. Others that know more should comment. I might get a short length of rubber hose and gentlly blow and suck on after hooking it up to the shut off to kind of check it although a mity vac type of device would be superior. (vaccum pump with gauge). Because of the large volume of smoke when starting now it does kind of partially rule it out. But if you establish using the archives if required that the glow circuit is working properly give it a whirl. Something vaccum related has let go for sure with the much faster depletion of your vaccum storage now.

the odd thing is it's only in the morning that it causes trouble. once she's up and running for the day, then it's no problem. i go to lunch, i drive back then after work when i start her, no problems.
i did notice some oil around my key switch behind the dash where the vacuum line runs to. i'm thinking it's gotta be glow plugs/relay. i'm just surprised because like i said earlier i live in florida. it's in the upper 60's in the morning. in the past i've often started her without waiting for the glow plugs.
i'll check the glow plugs after work today.
thanks,
dale

it means one of your vacume controls is open to engine oil. and VERY SOON your vacume lines will fail.
usually it is the engine cutoff valve leaking into the vacume lines.
if you have oil in the lines, most if not all of your lines need to be removed and replaced. oil will destroy them and the valves they run to.
now I am no expert, just a newbie, but I have done a lot of reading on these MB's, and that is what I have found to be true.
jm.02,
John

If this is so and I have no doubt about the last posters information. Find the oil intake point fast and either isolate it or replace it. Flush your vaccum lines out should work at saving them if you act reasonably quickly. Now I guess you do need a vaccum pump device to see if you are pulling oil from the pump solenoid mind able to pull a vaccum.

i didn't really understand that last sentence in the previous post. i do have a mitey vac pump. what are you saying i should do with it to figure out where the oil is getting into my vacuum system? off the top of my head i would think the vacuum pump itself would have to be the source. what are other likely sources? how would i check to see if it's the vacuum pump. the car does seem to have enough vacuum to run everything when the engine is running.

dale

Sorry Dale for not being clearer. Since you have a mity vac you want to hook it up to the shut off solenoid on the injection pump. Normally you should be able to hold vaccum for quite a long time but suspect from your descrition of things the injection pump solenoid might be ruptured internally. Also if you think about it the oil is not coming fron the vaccum pump. The pump only creates a vaccum at no time does it create a pressure to drive oil through the system that I can presently think of. In fact what may be happening is the vaccum pump is pulling oil from the injection pump through your defective shutoff solenoid back down the line through your ignition swich tubing trying to pull it back to the pump. Of course in one switch position the oil just runs out of the valve assembley on the key switch. The pump is just doing as it should. Now if your mityvac proves your shut off is indeed deferctive you should read all the pertaining archives before you change it. Especially how to get it installed correctly as well as the setup to prevent a runaway diesel. Not alarmisim but just good common sense. But first you have to prove the shut off solenoid is bad and that should be pretty easy with your mity vac. Just seeing oil in the line near the injection pump kind of confirms it anyways as there is probably no other way oil could land up in that line that I can think of.

Dale,

Makes sense that the engine would start harder in the morning. It has longer to cool overnight at lower temperatures than during the day when its warmer especially in the sun.

Its not the vacuum pump. The air flow is toward the vacuum pump.

It has to be a vacuum line that is exposed to oil which could mean the shut off diaphram is leaking. Take your Mitivac and pull a vacuum on the brown vacuum line at the IP. If it doesn't hold a vacuum, the diaphram is leaking. U might also see some oil in the Mitivac.

P E H

Barry,

U and I are on the wave length and I didn't see your post until after I posted.

Its just a coincidence that Dale had the 2 problems at once. GP and shutoff diaphram are his problems.

P E H