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1983 300TD, 115,000 miles. Anthracite Gray
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Discussion Starter #1
Hi folks. Left the light on the back of my 300TD, ran down the battery. Jumped it this morning--and apparently blew something out in the vacuum system in the process.

I don't understand it--but once I got it started, it wouldn't stop. Rather, after I shut it off and remove the key, it keeps running for several minutes. Then, after 10 minutes or so, it gradually shuts off; presumably the pressure is building slowly.

So, after an online refresher course, I got out my Mityvac. Pump is pulling a good 21 inHg. Pumping down the supply to the shutoff valve shuts off the car, so the valve is fine. So: vacuum leak.

I connected my gauge to the brown line (with blue stripe) that leads from the shutoff valve into the region behind the dash. That line will NOT hold a vacuum.

So, something happened under the dash, apparently, while I was jump-starting the car. Maybe it somehow created a positive pressure and blue out a connection? No idea. But whatever caused it, now I have to fix it. So, how do I get to those vacuum lines inside the passenger cabin, on the other side of that feed-through on the firewall? Somehow I need to get in there and see what's happening. Or, does anyone know what's going on in there?

BTW, remote door locks aren't working either, presumably because this leak is compromising the whole vacuum system.

If you someone could lead me to an online reference, that would be dandy.

Thanks,
Jim
 

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1983 300TD, 115,000 miles. Anthracite Gray
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163 Posts
Discussion Starter #2
Quick followup: I've done a bit more reading and understood that normally the brown/blue line is the vacuum "supply" to the ignition switch and the brown line is the line to the shutoff valve. (Apparently they're reversed in my car; I'm guessing that doesn't matter much.) My question above simplifies to, what goes on at the ignition switch? Is it simply a matter of passing the vacuum when the switch is turned off? Or are there other connections?

The other question: How do I get to those lines at the ignition switch?

Thanks,
Jim
 

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1984 300D
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You might have to pull out the Instrument Cluster to get at that area.
You need to pull the Hose off of the Vacuum Shutoff on the Fuel Injection Pump. If there is Engine Oil in the Hose your Vacuum Shutoff is on the way out; however it may still shut off the Engine.
Connect the mighty vac and pump slowly and watch the gauge to see how much vacuum it needs to shut off and then see if it will hold vacuum.

As you noted there is a Vacuum shutoff valve on the Steering Colum and it does matter which way the hoses are connected.

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1983 300TD, 115,000 miles. Anthracite Gray
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163 Posts
Discussion Starter #4
>>You might have to pull out the Instrument Cluster to get at that area.<<

Thanks.

>>You need to pull the Hose off of the Vacuum Shutoff on the Fuel Injection Pump. If there is Engine Oil in the Hose your Vacuum Shutoff is on the way out; however it may still shut off the Engine.<<

Done. It looks fine. No oil.

Connect the mighty vac and pump slowly and watch the gauge to see how much vacuum it needs to shut off and then see if it will hold vacuum.<<

I didn't notice the amount of vacuum, but I did check to see if it would hold. It does. Vacuum leak is upstream.

Thanks,
Jim
 

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1983 300TD, 115,000 miles. Anthracite Gray
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163 Posts
Discussion Starter #5
New Symptoms!

Wipers don't work.
Turn signals (flashers) don't work
Horn doesn't work
(fuse 2 looks fine)
Battery light is on.

Jim
 

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Brown 83 300SD I have a few other projects before I get to her!
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1,845 Posts
New Symptoms!

Wipers don't work.
Turn signals (flashers) don't work
Horn doesn't work
(fuse 2 looks fine)
Battery light is on.

Jim
Hi Jim, take it to get tested to see if the problem was caused by a dead short in the first place. Make sure the there is no juice being drawn while the vehicle is shut off.

I think I got lucky w my vac system. When I first started driving it the car would shut off w the key. Then it would only shut off w the stop lever or locking the pass door. Now it's back to shutting off again. My fuel door & trunk functions fine, locks work except the front pass door won't go down w the vac but comes up w it. The first time it happen w the fuel door I was at a gas station & couldn't get the fuel door open. People had to think I was NUTZ! I was calling my friend that had an SD, he thought I was insane too I bet!

I've been using Diesel Kleen Power Service, I don't know if that had anything to do w it, but it idle's better & has better power esp after dead start, still a lil slow but I can deal w that. 28 year old car w 320K. It's like being able to talk to my old great great granpa! I'll take it!

Keep us posted, best of luck & research,
Dave
 

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1983 300TD, 115,000 miles. Anthracite Gray
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Discussion Starter #7
Thanks Dave. It's becoming clear that I am in need of professional help. ;-)

That Diesel Kleen is just a fuel additive, right? I'll give it a try.

Best,
Jim
 

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Brown 83 300SD I have a few other projects before I get to her!
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Hi Jim,

That's the only thing I've done was to keep an additive in with the fuel so as to keep the IP & inj's lubricated because these vehicles were designed to be run on LSD not the ULSD that were are forced to buy now' Better yet would be Biodiesel of any blend B5, B10, B20, or higher. I did run a few tanks fulls of B20.

I was just happy that the car ran so I was willing for now to live with the car not shutting off, but the car seemed to fix itself & that's the only thing that I've done was to add the Diesel Kleen. I do that with all my diesels until I can find Methanol & Lye locally so that I can make BioD. Just picked up a used processor that I bought used on Ebay! Cant wait.

You have short somewhere, I'm really not good at chasing electrical gremlins either. Not fun for me.

Dave
 

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Brown 83 300SD I have a few other projects before I get to her!
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BTW, one thing that could help would be to check your fuses & see if one is blown!

Good luck,
Dave
 

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1984 300D
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I found out that when you check Fuses you actually need to pull the out and inspect the tips and where the tips make contact.
 

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Brown 83 300SD I have a few other projects before I get to her!
Joined
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1,845 Posts
I found out that when you check Fuses you actually need to pull the out and inspect the tips and where the tips make contact.
Yup, & also only use the copper fuses.
 
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