Question about 1984 Mercedes-Benz Mercedes Benz 300 Class
A new engine was installed four years pryor. It ran fine when I parked it. what should I do to get it running? is it worth the effort?
Ok, I got you, so read carefully:
These engines are the toughest on the planet. You can DEFINATELY get the engine running again, and cheap. Here's how:
First, DO NOT use starting fluid on any diesel. It'll make it go big bang due to the compression being twice that of a gas engine.
Diesel does not varnish like gas does.
New injection pump? No way, not on these engines. It's fine.
Diesel fuel grows a type of algae after sitting awhile. It'll be black and nasty and it clogs stuff. You 300D has a screen filter in tank, and then a plaster prefilter as well a secondary spin on filter on the engine.
1. Make sure your battery is fully charged. If bad, then replace it with a new one. Mercedes uses big batteries, but they're only about $85.
2. Replace the plastic pre-filter. About $5. It's on the driver's side of the engine, near the hand pump. Just unscrew the two hose clamps and insert new one. The old one may be black inside due to gunk.
Here's a pic:
It'll have a 90 degree elbow on in it. It's right about the "FEED" label in the pic, just below the injection pump. Just unscrew the two hose clamps and pull out filter. It may be black at this point. You'll only lose a small amount of diesel, It's not pressurized.
3. Now replace your spin on fuel filter, bout $10.
Here's a diagram:
You can take a large adjustable wrench to loosen the top bolt. Then you can spin the filter off, just like an oil filter.
Pour that diesel into the new filter. You can also add any additives to the filter to help clean the system. I use a small amount of transmission fluid. There's also and additive made by Red Line called "85 Plus". That stuff is like giving an anema to you diesel. Works great. Pour a little of that into the filter too.
Fill it to the tippy-top, then screw back onto bolt. Tighten that top bolt so as not to leak.
Now you got a good battery, and clean fuel. Start that ****** up. Cycle your glow plugs a few times if it's cold outside. Then just drive that thing. And I mean DRIVE IT HARD. It'll help move all that gunk through your system.
If the gunk is really bad, you may have to go back and clean that in-tank screen, but this should get you going for now!
Please leave feedback if this helps you out! Good luck!
Posted on Feb 10, 2009
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