Roger that, thanks. I'll do the leak down test as soon as I can and report back. Good point about a hole in the piston would have a ton of oil out the tailpipe...even after I restarted the engine the next day, an engine bounce at idle, but no blue or white smoke...no smoke at all out the tailpipe until I ran it up when engine shake became less but had light black unburned diesel out the back. I didn't know that diesel exhaust valves could burn even with a good lash. After all is said and done, whatever the cause is, which I'll report here for everyone's benefit as no one should have to go through this, I'm going to make sure the waste gate is working.

if it had been filled with gasoline instead of diesel very bad things can happen including cracking cylinder walls and piston damage. It's a long shot but one of my lovely daughters filled my 74 240d with gasoline then took off to drive 200 miles home. The number four piston being low suggested to me it got very hot and damaged two cylinders.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

What is the clearance on the valves for #5?

Compression test is meaningless without a valve adjustment - you are wasting your time until you complete that first, and then test the compression.

Remember that a diesel engine needs compression to ignite the fuel, so a tight valve = low compression = no ignition of the fuel. Hard to do a lot of damage after the valve(s) get to the point that there is zero compression, but you may indeed have burned a valve.

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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

[QUOTE=Maxbumpo;3917299]What is the clearance on the valves for #5?

In his first post / line item 1 he states

As long as there is any clearance, miss adjusted valves won't cause a total loss of compression.

Missed that. I was looking for where he adjusted the valves.

Why not follow the steps in the service manual: adjust the valves on a cold engine, measure compression.

Continuing to operate the engine at this point without adjusting the valves is negligent.

Hi....the engine is not being operated at this point after the miss...just sitting now waiting for tools to remove the preignition chamber so I can send down a video bore scope and take a look. I'll be getting an extension to my compressed air line so I can reach from my garage to where the 300D is parked so i can try the leak down test, which is a good idea. Adjusting the valves was on the bucket list of to do items shortly after getting the car, and replacing the transmission, doing brakes, diesel purge, and preparing for injector replacement with valves...just didn't get to it yet. But I still maintain that loose gaps shouldn't cause compression to go to zero suddenly...something pretty spectacular must have happened. I should have the tool by weeks end, and I'll post pics of what I find, plus leak down results. I figure I'll have to pull the head, and I'll document that too for everyone's benefit. If something dumb happened, like a stuck waste gate cooked a piston/head gasket/valve, I'll let everyone know asap. One great thing about forums like this is we can save others from possible pain...

Adjusting the valves is a waste of time at this point. If there's daylight (as indicated) at the cam at TDC, the valve is closing. A few thou of lift at TDC is not causing this problem. 10/10 the head will come off if the motors gonna be repaired, and they can probably swap a good runner for less than repair cost.

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CC: NSA

All things are burning, know this and be released.

82 Benz 240 D, Kuan Yin
12 Ford Escape 4wd

You're four times

It's hard to

more likely to

concentrate on

have an accident

two things

when you're on

at the same time.

a cell phone.

www.kiva.org It's not like there's anything wrong with feeling good, is there?

That's the plan...as long as the piston looks OK with the scope and hopefully if I can still see some crosshatch on the cylinder walls, I'll take a stab and pull the head and plan to order a rebuilt from Metric Motors...the old dollar bill test indicated a suck back at the exhaust, and I'm figuring after a leak down test, all bets will be on a burned valve.
Question...has anyone heard of a stuck waste gate cooking one of these engines?

Yes, excessive boost can severely damage them. Think melted pistons, seized engine. I would expect you would see far more damage than what you have. Generally that sort of damage occurs during full throttle acceleration to very high speeds, or pulling a really large load. Cruising at 70 doesn't really fit the scenario.

I'm thinking you've got a problem with the camshaft or the valve or the valve seat. Did you check the camshaft lobes for that cylinder?

The waste gate on my old 617 got stuck crusing down the freeway I lost power and the engine caught fire. After I pulled over and extinguished the flames from mostly the air cleaner fire and after everything cooled i restarted. Had the safety cut off not worked sure I could see melted pistons.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

DieselBenz1 just cited a real concern...I'm going to check my wastegate or just rebuild the turbo before I finish the engine...speaking of which...
Today I did a leak down test...HarborFreight has a cheap kit to do this for gads engines, and with a few fittings from a compression tester, I was able to pump air into number 5. Wouldn't hold any pressure, but I did hear and feel air coming out of the adjacent injector hole for number 4, which confirms a blown head gasket. But no bubbles in coolant or loss of coolant or anything in oil that I could see, which surprises me. From what I've read, most blown head gaskets come from overheating these engines, although excessive boost could of course do it. And no way of knowing if this engine was overheated in the past...wish there was a high temp wax plug or such in place one could see if an overheat happened. On Monday I should have the tool to pull the precombustion chamber so I can get a view with the video scope...I'll post pics when I get that done for everyone to see. In any event, looks like head is coming off...

If you had a failed head gasket between cyl 4 and 5 , compression between the two would be the same ( zero )

If you have a burnt valve on cyl 5 and cyl 4 has a exhaust valve that is open due to normal firing order, you will get air out of cyl 4 injector.

In any event, if you got cyl 5 to TDC with both valves closed, and got air out the exhaust pipe, there is a burnt valve.