Author Topic: 300sd was idling, then died... now won't start. Suggestions? Here's the story...  (Read 280 times)

girlwithoutaplanet

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  • 1979 300SD
  • Location: Portland, OR, USA
My 1979 300sd sat for a while. I started it, moved it into the driveway to change the oil. It ran fine, everything sounded normal. A few days later, started it again and we were flushing the power steering when the engine just suddenly died. To me, it sounded like it just ran out of fuel and died out. He was watching the engine when it happened, there was no seizing up of anything in particular. Now it will not start.

We were baffled! and it gets even more weird.... Randomly, I checked the tank filler flap... the cap was gone and there were small, bright colored balloons tucked inside. (like water balloons?) A few of them further down the neck. Something had caused the rubber of the balloons to degrade and they easily ripped open when I was holding one (wearing gloves). I first thought drugs? Someone was stashing drugs in my tank filler? No, not drugs. It was super tiny white balls, really similar to a desiccant!
(You can take a look here, if you want: https://photos.app.goo.gl/ccySXmgdJVfYMa6V9)

Before beginning the process of cleaning out the tank and the fuel lines, we wanted to be sure that the engine wasn't damaged in some way. So i tried starting it from an auxiliary tank. Will not start.

Changed fuel filters, tested fuel/lift pump - works fine. Fuel goes through.
Tested fuel injectors, they spray just fine, no leaks.
Did valve adjustment, just in case. only 4 of the 5 intake valves needed a very minor adjustment.
Compression test...came out unsure. I actually think that the tester gauge is shot, but I'm going to pick up another kit to try here soon.
Tried the return flow valve, on the back of the injection pump. That valve looks different than the ones I saw online..clearly someone replaced it at some point with some random Bosch valve. But really, fuel is flowing into the return just fine.

Fuel to the injectors is happening, but it sure doesn't seem to be a lot when we loosen the hard lines at the injectors.

So the concern is that something did contaminate? and it's stuck in the injection pump? Which is now unable to provide enough pressure to the injectors.

Does that make sense? Is there some secret trick to test the injection pump?

Anything else that I'm missing?

Glow plugs are fine - remember, the car started just fine! It literally choked out while idling. As if it just lost fuel flow.

1979 Gold 300SD - Gogo, The Lady of Metal

rumb

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That could be crack cocaine. Pretty sure it's drugs.
'68 250S, '77 6.9 euro, '91 300SE, '98 SL500 '14 CLS550

girlwithoutaplanet

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  • 1979 300SD
  • Location: Portland, OR, USA
That could be crack cocaine. Pretty sure it's drugs.

I thought the same. But it had no odor to it (granted, the rubber of the balloon just smelled like diesel) and it was literally in perfectly shaped, tiny balls.

At first I found a few other balloons that had opened, the substance inside was congealed into one whole blob.

But that is just a super weird mystery to which I will likely never get the answer.

Instead, I'm trying to figure out...... Why did the car die out while idling? Why isn't it starting?? Is it really possible that somehow some of that substance made it all the way through the tank screen, through the fuel lines, through the in-line filter, and into the injector pump to cause some blockage and decrease the amount of fuel pressure??? I guess anything is possible in this situation.

How can I test if the injection pump is really dead?
1979 Gold 300SD - Gogo, The Lady of Metal

goldacre

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Hi Girlwithoutaplanet, I’m reaching here but maybe this is worth checking out?

I have a pickup with a turbo diesel motor using a mechanical diesel pump and on those forums a common but unknown place to look is where the fuel line from the fuel filter meets the diesel injector unit. Undo and get a very fine piece of wire or maybe a magnet and inside is a thimble shaped micro fine metal gauze filter which often accumulated rubbish and wax etc. investigate if you have one of these as it’s a common problem on diesels that have them as it’s not obvious given it sits inside the fuel line body of the injector pump.

If you do have one be very careful when cleaning it as it’s a delicate piece of fine work, just soaking in fuel cleaner and applying light pressure via a fuel cleaning spray can should do the trick.

Best of luck!

G
12/1979 450 SEL 136K on clock (museum piece)
12/1986 Lotus Esprit Turbo 87K on clock 'Darling, look what Q has brought for us, isn't it nice' :)

girlwithoutaplanet

  • Enthusiast
  • *
  • Posts: 42
  • 1979 300SD
  • Location: Portland, OR, USA
Hi Girlwithoutaplanet, I’m reaching here but maybe this is worth checking out?

I have a pickup with a turbo diesel motor using a mechanical diesel pump and on those forums a common but unknown place to look is where the fuel line from the fuel filter meets the diesel injector unit. Undo and get a very fine piece of wire or maybe a magnet and inside is a thimble shaped micro fine metal gauze filter which often accumulated rubbish and wax etc. investigate if you have one of these as it’s a common problem on diesels that have them as it’s not obvious given it sits inside the fuel line body of the injector pump.

If you do have one be very careful when cleaning it as it’s a delicate piece of fine work, just soaking in fuel cleaner and applying light pressure via a fuel cleaning spray can should do the trick.

Best of luck!

G

Interesting idea! I will definitely look at this.. From the fuel tank, the line attaches to an in-line filter that goes right into the lift pump (simple fuel pump), which does seem to be flowing just fine - disconnected the return line and it squirts while we pump the primer. The lift pump is attached to the injection pump, which is not something I want to take apart. But maybe we do need to remove the lift pump to take a good look, maybe the connect into the injection pump is clogged?

Thanks!

1979 Gold 300SD - Gogo, The Lady of Metal

goldacre

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Hope something comes out of it, these fine gauze filters are the last chance to protect the finer inner workings of the injection unit. Not familiar with the Merc 5 cylinder diesel but thinking it would have a last resort protection, hopefully the fuel line is like mine in the pickup, a banjo fitting on a metal fuel line? If you have a rubber one the rubber will perish and drop bits hopefully stopped by that gauze filter but gives fuel delivery issues. From what you say the Merc has a delivery pump to pull fuel up to the injector unit which has the 5 lines going into the cylinder head? On my pickup the diesel injector is the sole method to pull then push the fuel into the engine, they are not smart injector systems but damn reliable  8)

Quote
“when you have excluded the impossible whatever remains, however improbable, must be the truth.”

Good luck!

G

12/1979 450 SEL 136K on clock (museum piece)
12/1986 Lotus Esprit Turbo 87K on clock 'Darling, look what Q has brought for us, isn't it nice' :)