I may have finally found my problem! I pulled the turbo charger and the exhaust manifold off the engine. The exhaust manifold was leaking at the bottom of #6, #4  exhaust ports. That’s part of my noise. The turbo charger has bad bearings and the oil seals are shot and that is part of where my oil has been going. But what I was able to see with all of that stuff out of the way is that my engine mounts are bad on the right side of the engine. The shock mount is just touching the steel shell of the mount that bolts to the frame. That is one known source for the knocking I have been hearing.

So I have ordered all the parts I need to fix everything. I have a way I can check the mounts to make sure that is the knock issue. So today has been very productive. I’d rather not have to pull the engine if I can help it. Even if it’s not the problem and I have to change the engine, everything I’m doing would have to be corrected anyway so it’s all good.

Well it's not the mounts. Found a plug for the turbo oil feed and blocked it off. Jacked the engine up enough to put some wood between the mounts flange and the support arm from the block. Cranked the engine and the knock seemed to be gone. Having been down this road before with this engine, I jacked the engine up, removed the blocks, let the engine settle back down and cranked it again. Knock returned. However, the engine had warmed up. So I jacked it up a third time, put the blocks back in and cranked the engine back up. Knock still there.

I've been reading this forum and some others till my eyes are crossed. About the only thing I've not done is fix the delivery valve leaks and change to synthetic oil. The tool to pull the DV will be in Tuesday and the turbo rebuild kit will be in Wednesday. Will see what happens after everything is back together.

I'm picking up a 603 from an '87 300D as a possible replacement transplant. If my original engine does have a bent rod, will this thing grenade on me or just die a slow death. I've heard some real scarey recording of other engines and read the advise of doing an "Italian tuneup" after adding MMO to the fuel tank. I have StarTron in the tank now but very little run time after adding it. I've had one big truck diesel mechanic listen to it and tell me that if it were a rod I'd be on the side of the road by now. So should I just run the hell out of it and see what happens?

I've had rod knock in other cars but not diesels. I could feel it though the whole car. This is something I can hear but not feel. The only thing I can feel is a difference in the feel of the injector line on one cylinder. However, when I open the line up with the engine running, the engine labors but the knock is still there.

I did the overhaul of my OM603.971 one month ago.It had that sound,and it turned out that it is a broken piston slamming on the cylinder wall .
Hope that this is not the case with yours,but it sure sounds the same .
And I had no change in the oil consumption,fuel consumption,engine power,no smoke from the exhaust,nothing except the loud knocking.

__________________
Mercedes W140, S350TD, 95.
Mercedes W140, S350, 92.
Porsche 944, 86 N/A.
Porsche 944, 85 N/A automatic.
Porsche 944, 84 N/A.
Porsche 944, 83 N/A.
Opel GT, 73.
Toyota Supra MA61,84.

Well I just picked up a '87 300 turbo complete less the IP. Looking at the engine, I don't think it's even had the valve cover off of it. My existing 350 is missing so many parts it's unreal. The yard had a second engine, the top was clean but below the intake and exhaust it was caked in oil; I left it there. The turbo is tight and shows no sighs of oil leaks. I'll do a quick rebuild to change the seals and bearing but I have a good feeling about this engine.

Finaly found some Diesel Purge. I'll run a couple of cans through the 350 as a last resort (SeaFoam did nothing) before setting everything up to do a transplant with the 300. If I do that, then the questions will really start to come. LOL. Did some searching and found many good posts on that process so far. More reading to do.

A better engine swap would be a turbo OM606, with intercooler. Keep you existing injection pump. This swap has been done more than a few times before, and the resulting car has more power than the original. Going backward to an older 603 will give you less power.

I'm still convinced you've got a sticky lifter, just need to switch to Mobil 1 oil and driver her for awhile.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

After reading this, really sound like it could also be a fuel/injector/injection pump issue.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

The socket to remove and rebuild the delivery valves came in today. Also found some Diesel Purge here local. So tomorrow I'm repairing the DVs and running the Diesel Purge through the engine.

I'm just not wanting to run a possibly damaged engine to the point of destruction if there is a chance it can be rebuilt. But I must admit that one engine I looked at sounded almost as bad as mine.

This knock came on all of a sudden on less than 1/4 tank of fuel. Traveling 60 MPH and the engine just coughed, dropped power and than went on normal, except for the knock. I added 10 gallons of fresh fuel with Lucas Injector Cleaner added. Knock has not gone away. I've considered pulling the pre-combustion chambers and inspecting them. I still have not given up on this engine yet. Just seem to be running out of options. My neighbor down the road builds sprint cars so he knows some about engines, he says it sounds like a bottom end rod knock. When it started it sounded like a lifter, so I lost as to the cause.

Redid the delivery valves. At least my fuel leak is fixed.

By passed the fuel tank and I'm running Diesel Purge straight out of the bottle. Seems to make a small difference in the knock. However, I noting small air bubbles from the return fuel line back to the bottle.

All I did was disconnect the soft lines from the hard lines to and from the tank. All of the fuel delivery system is intact, just being fed from a bottle of DP.

Could an air leak to the injector pump at either the fuel heater or fuel pump be giving me injector nailing?

Should I hook up directly to the fuel pump inlet for the supply?

Yes. Sounds like you may have found a possible cause...

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

That didn't cure it. Took everything out of the system except the fuel pump mounted on the side of the injector pump and the injector pump itself. If anything, as the engine gets hot the knock gets worse. Now the engine is really vibrating and shaking the entire car.

I may take the injectors out of the 300 that I have and see if they make any difference. Other than that I'm about ready to give up on this 350.

Thanks again for all your help.

Here is the engine running on Diesel Purge. Knock is not getting any better! In fact it's getting worse. About time to start on the transplant.

DSCF0151.mp4 Video by Precision32 | Photobucket

Like I said 99% sure that it is a piston slap .Because my engine made exactly same sound.

__________________
Mercedes W140, S350TD, 95.
Mercedes W140, S350, 92.
Porsche 944, 86 N/A.
Porsche 944, 85 N/A automatic.
Porsche 944, 84 N/A.
Porsche 944, 83 N/A.
Opel GT, 73.
Toyota Supra MA61,84.

The 350 is tired. With the manifolds off oil is coming out of every cylinder.

I'm to the point that I rather put a sound engine in it's place rather then take a chance of being stranded on the side of the road.

I don't know if you can see it in the picture, but the ALDA system was hooked up to vacuum, not intake manifold pressure. So this thing had NO turbo boost at all. The 300 may be smaller but it will be a major improvement to what the car has been.

I'll do a autopsy on the 350 and report back as to what I find.

Wow! Maybe worn valve guides / valve stem seals? Hard to imagine that a head gasket failure could affect all cylinders.

Very sorry to hear that!

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

I think it's the rings. With the intake manifold off I can watch the valves as the engine is running. No oil is visible at the valves when the engine is running. There is a lot of oil coming out of each of the exhaust ports of the head. As the turbo is off the engine it's oil return line is open and there is smoke, and a rather large volume at that, coming out of the crank case.

All in all I would say that this engine has reached the end of it's life. Now I need to open the engine up, after the other is put in it's place, to figure out if the block is usable. I love the car and it drives like a dream so IMHO it's worth the effort to swap engines and keep it going. They're not making many of these anymore.