1982 mb 300sd

i have a 1982 mercedes 300sd that i am unable to get into trunk.the key fails to open it for some reason.any help will be useful and thanks in advance.

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Are you using the square headed key and is it turning?

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Yes but more likely your alarm system is causing this problem... use driver door to lock and unlock the car until you can pop the trunk. The trunk key hole must be in horizontal position. Once trunk is unlocked, go to passenger side front seat under the floor mats and plastic... unhook the harness and tape it up.
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Get a can of graphite libricant. It usually comes in a spray can with alcohol as a carrier. Spray it in there.
What usually happnes is the lock mechanism gets all gummed up and the key won't turn (although it usually will if you use pliers but you run the risk of breakig the key).
That lock is supposed to be libricated with graphite once a year.
Many people will use WD40 whch works short term but turns to hard gum and makes the problem worse long term.
Squirting some rubbing alcohol in there usually works too. This is what "lock de-icer" is. But that just frees it up you still need to lubricate it with graphite to fix it in the longer term.
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Richard,
I am a locksmith and have seen many locks apart and on the bench.
A couple of observations. First WD40 is mostly solvent and does not turn to a hard gum.
Graphite works great as a lock lubricant, but if you apply it to a lock that has grease inside, you get carbon impacted grease that can be a mechanical problem as it takes up space that the tumblers need to wiggle and slide.
The big advantage to WD40 is that it is cheap and everyone seems to have a can or two around the house. If the lock is gummy, flushing with WD40 until the outflow runs clear will not hurt anything. Once the solvent evaporates then a puff or two of powdered graphite is great.
The real gummy stuff are products like 3 in One oil they will suck up dust and then dry to a sticky goo.
Products like carb cleaner are good for degreasing a lock, but you have to be careful as they might damage the paint.
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Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.
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Not really. It's an oil dissolved in a petrolium carrier. Eventually the oil does what all oils do - gets thicker with age.
MB recommends graphics and nothing else for locks. Locks that have had years of WD40 sprayed into them eventuallyget tobe a gummy mess. All you can do is chean them throroughly then lubricate properly with graphite.

True.
True but you are leaving a petrolium lock residue behind. Once or twice probably won't hurt it but long term, using this stuff regularly does caue problems. Lots of people have noticed this with their cars.

Alcohol seems to work ok. Any polar solvent will really...
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wrote in message

Yes there is a thin oil film left after the solvent evaporates. Now just how sticky or gummy is it? Try this, take a coin and wash it with dishwashing soap. When dry spray it with WD40. Set it aside and let it dry out. Now feel the surface.

From the factory the locks are greased. That is a lot of petrolium residue, the thin film left behind from WD40 is a whole lot less. It does no harm, but admititly it is not the worlds greatest lube.
I would qualify the "does no harm" in circunstances like wheel bearings that are suposed to be packed in grease, there it would flush out the grease leaving the bearing without enough lube. In my experience as a locksmith since 1977 most lubrication problems in locks are from not lubricating them, hence the "does no harm" position.
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Now do it every year for 10 years. That's the point - with *age* the oil turns into a gum and is why you don't want to shoot WD40 into the lock of a Mercedes. Them parts get all gummed if in time if you keep doing this. Which is why the *factory* insists on graphite *only*.
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the fuel pump is located on driver's side near the injection system.there is three nuts holding the pump on but they seem impossible to get to. please help in informing me on what to do and if any special tool are need. thanks in advance for any help given. jdsm711
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jdsm711 wrote:

the back of the pump but even that one is not that hard. Just take your time. Now, remember that you have to get the timming right, so oyu may want to leave the engine at TDC.
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Hi there,
My '84 SD sometimes does the same thing. I unplugged the alarm, but that didn't do anything. I think the latch mechanism is catching. If you haven't seen it, there's a manual release wire on the floor, by the driver's side of the back seat. Pull the wire a bit and try the trunk.
Worked for me.
Tim
jdsm711 wrote:

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