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Old 12-18-2011, 03:07 PM
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Join Date: Apr 2005
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1976 w116 multiple issues

Have only had car for 10 days. so time to figure out all the issues.

Interior gauges. Worked about a week ago. oil preasure, speedodometer still work, none of the others. Fuse?? No back up or brake lights either.

Interior tempurature: High and low fan work, but no heat- where should i start on problem.???

behind the warm up regultor are 2 things screwed into the block with vacuum hoses connected to. what are these? need to replace, each one has one hose connector broke.


Last edited by coolstuff; 12-18-2011 at 10:55 PM.
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Old 12-18-2011, 11:08 PM
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Location: Surprise, AZ, USA
Posts: 3,439
It sounds like you have a bad neutral safety switch on the transmission. When the reverse part of the neutral safety switch fails, it causes the reverse lights, brake lights, and I believe also some of the gauges to not work. The car can still start with part of the neutral safety switch being bad.

This may not be your problem, but it is my guess. I had the same thing happen to me and that's what my problem was. The oil pressure and speedometer are mechanical gauges that do not use electricity.

It sounds like you have a bad climate control servo (located under the hood on the right [passenger] side of the firewall). It's a very complicated heater valve that uses coolant, electricity, and vacuum to maintain the coolant flow into the heater core.

I don't know the answer to your other question because I'm more used to working on diesel engines.
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1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Highly Optioned, 347,000+ Miles
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Old 12-19-2011, 12:55 AM
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Location: brisbane,Qld.Australia
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Those temp sensors for the cold start valve and vacuum advance. Replace them both so the car runs properly.
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Old 12-24-2011, 09:55 PM
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Tested the circuits at the panel- #s 4, 5, 7, 11, 12, 13, and 14 do not have power.

where is a good place to start for power feeding these?
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Old 12-26-2011, 10:49 PM
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Join Date: Apr 2005
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No electrical issues afterall. Bad fuses. Seemed too simple. they all looked good, Also turn the key to run, or have car running when testing cicuits. Duh.

Only problem left-no heat. Are the 2 vacuum sensors behind the warm up regulator related? Replacing them, existing ones are broke. One blue and one black.
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Old 12-30-2011, 10:46 PM
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Those two vacuum fittings are sensors that control vacuum circuits for the EGR system (if so equipped) or various fuel management functions, since it's likely a D-Jet..round or oval air cleaner?
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Old 12-31-2011, 08:53 AM
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Join Date: Dec 2011
Location: Wisconsin
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Since you do not have heat, look at the servo first. That is mounted on the right side at the firewall with 4 heater hoses running into the bottom of it and a block of colored vacuum lines in the top. These are notorious to go bad and from reading on this forum they all go bad. My understanding is even Mercedes says it is a bad idea in these cars. You have one of two choices. Replace the servo with a rebuilt aluminum bodied one or go with an aftermarket solid state digital set up. Either way, prices are nearly the same but the solid state setup is more work to install, however, longevity is the key. A rebuilt servos life expectancy is unknown. Some last a short time, some last longer. Do some reading on this forum and you will find opinions on both. For me, I will be replacing it with the aftermarket setup that eliminates the servo. Here is the link for the one I will be purchasing. It comes with everything needed to do the replacement even though not everything is pictured. I talked with them the other day and the gentlemen I talked with was really nice and had plenty of information to offer. Good Luck!
Mercedes Benz Parts & Accessories - Mercedes 116 - CLICK HERE
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Old 01-02-2012, 04:15 PM
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Join Date: Apr 2005
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is this something I can handle decently if mechanically inclined? Or better to be border line rocket scientest? ( how difficult on scale of 1 to 10)

Has an newer aluminum servo already. BUt probably bad already by sounds of it.
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