Changed the head gasket on the car and it had a catastrophic failure after about 500 miles. Car was running OK prior to the change. It ran very rough one day with an internal sound. After a short while it died and engine seized. I removed the head today and this is what I found. The piston took out the intake valve plus the lifter on cylinder 6. It left a big hole in there as you can see from the picture. I could put the engine back together as I have a spare piston and head. However, I am wondering how this failure mode could happen. I don't want to put it back together and it fails again. Any theories?

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__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

Did you remove and re-install the valve when you did the head gasket?


another possibility is that a bolt or a nut fell into the manifold when you changed the gasket and it finally made it's way to the intake valve

I did not remove or re-install the valve. Not sure with any foreign objects but who knows. I have done HG replacement before and I follow this procedure. Am I missing something?

1) Zip tie the cam sprocket to the timing chain to maintain timing.
2) Remove the head, check and give it a good clean. It may necessitate rotating the cam randomly a number of times.
3) Rotate the cam back to the old position to make sure it 'mates' with sprocket.

I always do it like this and it always works. Had I altered the timing? I would expect any problem would manifest itself immediately, not after driving it for 500+ miles.

__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

"The piston took out the intake valve plus the lifter on cylinder 6."


Absent a failed connecting rod allowing a piston to be in the wrong place at the wrong time; The only way the piston could have come in contact with the valve is if the valve was in a position it shouldn't have been in.



Seem like the valve stem maybe broke and the valve dropped into the combustion chamber bringing its head into contact with the piston. Could be the valve spring failed and allowed the valve to droop into the cumsbustion chamber a bit.


Have you found the missing valve pieces?


I bought am 87 TD with an engine that had an at speed timing chain failure, it suffered a pair of bent valves, a bent connecting rod, and it broke the camshaft in three pieces.

It seems all the debris are there. Broken valve stem, hydraulic lifter broken into 2 pieces. It is puzzling.

__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

If the lifter broke in some fashion could have reduced the valve clearance.

Is physical breakage of a lifter possible? As rare as anything can be it still remains a possibility. Or more likely if the stem keepers somehow failed to do their job. At speed the hydraulic lifter would be trying to make up some of the difference.

As the hydraulic lifter continued to load up. The piston would be banging the valve. Not enough time for the valve to fall into the cylinder.

Something happened and the explanations for it are limited. At least in my opinion. I even wondered if a big chunk of carbon got in between the valve seat and the valve. Yet not likely as you had the head off not long ago. A foreign object doing the same thing. It should be found if it was.

Speculations at best.

Good luck with your project.


That's a very unusual failure

Look at the end of the broken valve stem and see if you can tell if it broke all at once or over time.

If it broke over time you will see something like ripples in the metal/like rings on a tree but. If it broke all at once it will be jagged with no pattern.

Diesel Truck Engines once in a while have a valve spring break and then have a similar issue.

I was looking at your pic of the Cylinder head but at the other cylinders. Assuming you cleaned it before putting it back on some of the other cylinder have oily carbon on them indicating that combustion was not going on normally.

__________________
84 300D, 82 Volvo 244Gl Diesel

? Do Mercedes use two piece alloy valves ? .

Many do and every so often the head simply snaps off and the piston hammers it into the cylinder head .

I ask because I *think* I can see the stub of the valve stem still in the valve guide...

If so and the valve adjuster isn't backed off and the valve collets are still in place it sounds like high mileage valve failure that sux .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

This is the pieces I found inside the valve cover and the damaged piston. The lifter was smashed and the valve stem snapped. Cylinder 6 the furthest from the oil pump, could it be the lifter was starved of oil? It has over 360K miles so metal fatigue may play a part?

I am going to put it back together with a spare piston and head and see what happen. Good luck to me.

Attached Thumbnails

 

__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

Wow! Was the valve spring intact? Was the cam damaged?



Plus, the valves on these OM603 turbo engines are sodium filled!

Can't find the valve spring anywhere. The cam is ok but I am going to use another one.

__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

I'd be concerned that the cam towers are tweaked, when the contact occurred forces within the valve train where spectacular, the weakest parts failed but experience lots of force in the instants immediately prior.

only the exhaust valves are sodium filled, the intakes are solid.


He snapped the intake valve.

603 doesn't have cam towers like 617. The cam is bolted directly into the cylinder head with caps