nonstarting 240D - Mercedes-Benz Forum

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post #1 of 5 (permalink) Old 03-07-2004, 10:06 AM Thread Starter
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nonstarting 240D

i own a 1980 240D. trying to crank up the car, the car is very inconsistent. in the time of my possession, the car has never run. sometimes (most of the time), it will not turn over. when it does turn over, it never catches and never actually starts to run. i have replaced the glowplugs. the wires running to the starter motor seemed chewed up, i will check them for current. ive even poured diesel down the intake manifold, but i dont want to flood it. the car has been sitting for a while and im wondering if it's just old fuel. could it be low compression? i am 17 years old and any help would be great.

P.S. dont let my age change your perception [B)]
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post #2 of 5 (permalink) Old 03-07-2004, 03:24 PM
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RE: nonstarting 240D

Hi Betenoire.

Firstly pouring diesel in the intake won't
do a thing.
Remove the glow plugs and crank the engine,
(stand clear diesel will come out with
some force)stop when no more diesel comes out.

Re-install the glow plugs.

Remove battery and trickle charge it.

Remove both fuelfilters and install new ones.
Main and inline.
Main one looks like a regular oilfilter.
Inline one is clear plastic.
Look for black crud in the inline one.
This indicates algea.

After installing new filters unscrew the
primer pump and pump it 50 times.

This should do the trick.
Once running have the valves adjusted ASAP,
because they most likely are out of adjustment.

Also if you have black crud add some algea
treatment to the tank every time you fill
You'll have to do this untill the black crud
You will have to buy a few inline filters
since they will clog up quick.
has a catalog that you can order free.
Highly recommended to order it.

The attached picture is from the catalog.

Edit:The picture doesn't seem to want to
Don't know what the problem is,never had
a problem before.

Just go to this link: gine

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post #3 of 5 (permalink) Old 03-07-2004, 04:03 PM Thread Starter
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RE: nonstarting 240D

Lou, thanks a lot. could you fill me in on the specifics of the problem..from what you've written, it seems like there is a fuel delivery problem. ive heard of algae buildup and the fuel down the intake..i had the urge to be dumb..i will follow the directions you gave me. this W123 is an awesome car and im proud to own it. the purchase price (drumroll) is $84 dollars. this has been a hobby and love of mine for a while and it's cool to add an "old-school" mercedes to my list of owned cars. hope we can keep in touch. could you answer more of my questions if i have any? thanks
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post #4 of 5 (permalink) Old 03-07-2004, 05:36 PM
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RE: nonstarting 240D

Well,yes and no.(fuel delivery).

It could just be the battery that is
That is why you need to trickle charge it.
Trickle charging is slowly charging untill
A diesel needs lotsa power to start,hence
the big a$$ battery.
A diesel starts by compressing air in the
cylinders,creating heat,glowplugs only heat
the air up so the engine has an easier job.
As the heat builds,fuel is injected,this
ignites the the mixture.
So if the starter is turning slow due to a
low battery the engine will have a hard time
building compression.

I don't know how long the car has sat before
you bought it and how long it has been sitting
since then?
As the car sits for a number of months the
fuel drains back into the tank and when
you start it the lines will have air in them.
Also condensation in the fuel will cause algea
to grow and plug up the inline fuel filter,
cutting of the fuel to the injection pump.

As a general rule,if you have a running/not
running problem the fuelfilters are the first
to look at.
Bad fuel,algea and airleaks can cause the engine
to stall,run rough and some other strange problems.

Next would be the glowplugs but since you already
replaced them we more or less can rule them out.
But not completely,because the question now is,
"DO they work?"
There is a fuse(Metal strip with a screw on each side) in a black little box on the firewall that
could be bad.
When you turn the key to the pre-glow position,
does the wire going from the black box heat up?
You should be able to see it glows red hot.
If yes,the fuse is OK.
Not,then check it.

Lastly the fuel injectors,they last fairly
long and are hard to check.
Although they might tell you themselves that
something is wrong.
You might hear them nailing,but this would not
have an impact on starting unless they all
are bad.
Most unlikely.

Concentrate on the battery and filters


Just ask and all of us will try to help
you find a problem/solution.

Good luck.
post #5 of 5 (permalink) Old 03-13-2004, 10:28 PM Thread Starter
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RE: nonstarting 240D

i forgot to mention, while i replaced the glow plugs, i went and bought a new battery. 850 cca. this is one of the reasons why i dont want to crank it up too many times, the huge battery cost almost as much as the car. for very basic thinking, i was also thinking of using "lighter" (viscous) oil...i haven't compression tested it yet, but im thinking that's a next. 300 psi for diesels is it? i also need to adjust the valves too. i was wondering if the wires and connections were ok. although the connections physically look ok, for example the ground from battery to the chassis, im not so sure if they're appropriately conducive..any suggestions on what gauge to use and how to "properly" connect them so there won't be a tangled mass of butt connectors and electrical tape under the hood?

P.S. I hear that the cylinder walls could "taper" out, therefore lose compression? how severe is that?

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