i'm hooked. just got another one. glow plug issue
 

I just got a nice 79 240d. for $350. it needs some minor work,but the body and int. are pretty nice. I first baught it for parts, but I realize its worth fixing. I'll post pics soon as i wax the oxidization off.
All I have to do is fix the glow plug system, and do a slave cylinder. I had to shift without the clutch to get her home.
I have boiled the glow plug problem to the relay or the ignition switch. Is there a way to test the relay? it is not turning off. I can hear the relay click when I turn the ignition to the on position but it never clicks off If i turn the the ignition switch back off the relay clicks again. I am prety handy with electrical stuff, but i have a mechanical engineer friend who is really handy with electrical stuff. All i need is to give him a little direction. the glow plugs are definitly always on.
Also I was looking at the ignition switch and it seems oily. like its seeping out the crack where the switch meets the steering lock assembeley. could this be the culprit. Does anyone know a testing procedure for this switch. I have a excellent multimeter, but i know only the basics on how to use it.
the oil thing i know is a seperate problem with the vaccume and ill search that one soon. hopefully there is not oil throughout the system. thanks in advance for the help. I'm going to look for a used relay today, but i dont want to just start replacing things. Maby I'll try cleaning up that ignition switch.

Your problem with the oil seepage at the ignition switch sounds like the (very common) issue whereby oil is entering the vacuum lock (shutoff) switch at the (electrical) ignition switch.

In short, this is a vacuum-controlled locking pin which - if non-functional - will eventually cause an inability to shut the engine off from the ignition switch. Most often, the culprit is the vacuum shutoff switch on the injector pump which, when it fails, will permit oil into the vacuum system itself. Not good.

(But you haven't reported a no-shutoff situation, have you?)

On the old cars, always run through the vac system rubber hoses, too. In my case, I had one vacuum port which was working, but marginal. This was sufficient to cause the no-shutoff condition.

Lou

glow plug issue solved
 

It was the relay thank goodness. the ignition switch is a hassle to get to. I found a relay for $20 at the boneyard. it seems to be working. It is raining and I have no garage so I'll test the voltage tomorrow. easy fix
It is amazing how things are so easily overlooked. It seems the p.o. replaced the entire charging system. probably due to this. The only reason I found it was the wire was glowing where it was connected to the glow plug.
by the way there are no problems with shutoff. it stops quickly. the door locks work well suprisingly. I baught the car because the interior was in good condition as my euro is not really. I havnt decided what to do with this car yet. maby I'll drive it until I fix up the euro.

Look at the thread below. I got one and it is step by step what to do. Everyone should have one.Below is a quote.

1985 300SD Sady
Registered User Join Date: Sep 2004
Location: Cincinnati, Ohio
Posts: 914


Glow Plug Trouble? Free Glow Plug Diagnostic Sheet!

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Winter is upon us... glow plug issues seem to be popping up daily. Stop posting new threads and email me, this sheet will determine the problem correctly every time.

If you are suffering from glow plug issues, I will email you a very helpful glow plug diagnostic sheet. It is just shy of a mb in size, and it is a .pdf, so I don't think it is possible to post on the forum.

Please email me at GlowPlugDiagnostic@gmail.com with something simple as the subject line so that I do not confuse it for spam, and I will forward you the sheet.

I created a separate email just for this, and I will try to check it often and respond quickly.

Hopefully we can figure out a way of just posting this to the DIY links portion of this site in the near future.

Someone helped me out when I was in need by sending me this sheet, I am just trying to return the favor to the forum.

I am having a little trouble

oops the above may not work with the relay on the 79. I think it is under the dash. Sorry.