Ok. Update.
Pulled injectors.
Nothing obviously wrong but #1 and #3 were covered with black oil.
Prechambers looked all clean and similar.

Took them to the bench and deployed the Pop tester.
Never used before but used Diesel Klean as I had it to hand.
All 4 popped at around 1500psi/10mpa which I think is about 100 bar.
Spray patterns were similar.
Gonna crank engine over With injectors out and lines bagged.
Lets see how it sounds.

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2009 Mercedes ML320 Bluetec

One test you could do while you wait for you compression tester is to crank the engine over (with the injectors on so you have compression, but with the fuel lines off so it doesn't start) and see if there is any pressure coming from the water reservoir or the oil dip stick. It' not a definitive test, but could indicate a blown head gasket.

EDIT: before doing that, it would be best to crank the engine over with no injectors at all to make sure you don't have any liquid (oil or water) in the cylinders.

Got ya!
Engine cranked over smoothly, with no obvious issues.

I had assumed the injector lines would produce fuel, so I bagged all 4, but there was next to nothing in them...
However, there was a lot of fuel dripping down the drivers side of the engine....
It was all over the block and running off the oil pan... had to mop it up.
Im wondering if it came from the loose pipe that comes from the injector overflow pipe that goes to the fuel filter housing on the front of the engine.

Mmm.

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2009 Mercedes ML320 Bluetec

check the fuel to coolant heat exchanger/fuel warmer

Thanks.
It had been bypassed when I got the car.

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2009 Mercedes ML320 Bluetec

I need to have a better understanding of your comment.
Will research before I ask further questions.

In the meantime, here is a little video I did of my test of one of the injectors.
I’m not an expert but it looked about right, and all 4 were similar.
Opinions?

https://youtu.be/ReFjWnqCOOc

So, I did a refresher on the Lift pump/IP failure possibility.

Can someone explain what I need to look for or test?

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2009 Mercedes ML320 Bluetec

rat nest in intake? cause run away?

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

I might crank over the engine with the injectors out. To see if any cylinder is spitting oil out. This does not explain the fuel it the oil though. I wonder about the front seal on the injection pump.


In any event do not try to start this engine. I might consider if the thin fuel and base oil mixture got up past the rings on the number 2 and 3 cylinders and the engine ran away on it.


A test I might attempt. Disconnect just before the lift pump. Apply ten pounds pressure. It should hold it. If it will not close off the return line from the injection pump. Test again. If there is some route for fuel into the engine it should indicate it by not holding the pressure.

Pulled the Air Filter housing and all was intact, so no sign of rodent ingress.

To clarify, I cranked the engine sans injectors, and it sounded fine... I did not notice any obvious ejections.

Anyone have any comments on my Injector test?

Thanks for that insight Barry!
Let me dig in today...

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2009 Mercedes ML320 Bluetec

Ive never an om601 go that many miles without blowing a head gasket. They generally blow out between the chain galley and the first cylinder; one of mine blew under load and ran afterwards, but with white smoke and missing. The second one seeped oil into the coolant system. I consider a head gasket a maintenance item at around 150000 miles after doing two of them.

Theyre not hard to change even for amateurs. Just be meticulous, change the head bolts, put things back where they came from, DONT DROP THE KEY FROM THE CAMSHAFT GEAR INTO THE CRANKCASE and for 150.00 youre back in business. You didn't overheat from the sound of it, so probably everything is fine u less you see otherwise when the head is off.

I've done threads here related to my OM602 head, you can search them up. Note, you'll need to grind the head down slightly on new truss head bolts. I tried two sets, one mail order one dealer, they all didn't fit the counterbores on the outside portion of the head. I ground the heads down about 1mm on diameter on a cheap harbor freight grinder.

Note: There's 2 socket head screws down in front behind the timing chain, very hard to see. Get them both before you try and get the head off.

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No joy today, even tho the Compression tester arrived...

Guess that Murphy's Law is in full swing...

I went out to put the battery on charge, ready for the compression test, and the hood wouldn't open!
I think the release cable slipped or broke.
After much searching, I found thread that say the release is accessible thru the grill... well I failed on that one...
Broke a hole thru the egg crate, and still couldn't find it, so I've been dead in the water today...
`
I have not drained the oil yet, as I wanted to wait until after the compression test for obvious reasons!

I just went back thru the pretty comprehensive pile of receipts I got with the car, that stretch back to when it was new...
No HG replacement mentioned, but in 2001, with 125,000 miles on it, #4 Injector was replaced...

There is a niggling doubt in my mind about the hypothesis that this started with the Headgasket...
I grasp that these HG's had issues...
But here is where I get stuck, sitting in front of my computer..

Here are the facts, and my rationalization....

1/ The engine, went into a runaway mode... This means it had access to an uncontrolled fuel source... The masses of black smoke, and oily stains on the ground is kinda solid evidence of that. There are only 2 places it could have got that... a/ Fuel, or b/ Engine oil.

2/ If it was the Head gasket, and...
a/ It blew between an Oil passage and a cylinder, I get it, but then it would have USED Engine oil, and the Engine oil level would have gone DOWN, not gone up, and nearly doubled.
b/ It blew between a coolant passage and a cylinder... it could explain the oil level going up, but coolant would have gone down, or pressurized the cooling system, or I would see water in the engine oil, or exhaust, and I have none of those... Plus its not a fuel source so doesn't explain the runaway!
c/ It blew between cylinders.... that explains none of the symptoms...

3/ Something failed in the fuel system...
a/ Injector broke.... but all 4 checked out close on pop pressure from my test.
b/ Lift pump or some internal seal on the IP failed, overflowing into crankcase, which the engine then maybe ingested via the PCV or other means...

I must say, I'm leaning toward 3b....

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2009 Mercedes ML320 Bluetec

I'm leaning toward 3b too

I wonder if the amount of engine oil it would take for a runaway would register on the dipstick. This is a lot more like a tractor engine than a racecar. Occams razor applies. The simplest solution is the most likely.