Engine failure

whitedog

New member
The back story is HERE.

I thought I would make some notes on this repair for anyone bored enough to read them.

Basically, the engine was running rough, had no power, was smoking and blowing the oil dipstick out of it's hole. All of these things point to a burned or cracked Piston. I talked to Dr. A about it and he said that the 04,05,06 engines don't break pistons. I seem to to recall that they went to Trapezoidal rod/piston joints and I know that this adds strength there so I wonder if this is the reason why they changed.

I did some testing and verified that the problem was #5 cylinder and since at that point nothing was to be done except yard it out of there, I dug in. The following are random notes:

The engine harness came off of the engine and laid over.

I sprayed penetrating oil on the exhaust bolts a day before.

Both A/C compressors came unbolted and moved to the side a bit as well as the condensor. No A/C lines were opened.

I removed the injector lines and covered them with Heavy Aluminum Foil.

Heavy Aluminum Foil is a great way to seal up open ports.

Dr. A suggested removing the transmission with the engine. It's a whole lot easier to get the flex plate bolts out and getting the engine and trans lined up is next to impossible in the van unless you unbolt the trans and slide it back. I think that this is due to the angle of the engine.

I put a floor jack under the transmission pan with the jack running long-ways so that it would roll as I pulled the engine forward.

Remove the cover for the cabin filter.

Choke up the lifting chain as much as possible and the same with the chain on the cherry-picker.

The service manual says to cut the piece of tin going across under the radiator to get the engine out and I did this. I don't know if I had to but it allowed me to move the engine forward about three inches before coming up and this allowed the cherry picker to clear the cowling.

I removed the Drivers side engine mount since it would have hit the A/C compressors.

The rear engine lifting hook is a balance point with the transmission attached.

I kept the transmission lines and dipstick tube attached during removal and are still on the transmission after it's separated.

There's one more bolt you missed and that's why the part isn't coming off.

Dr. A told me to put a board over the cross-member and power steering cross member and just drag the transmission across that. After I got it out so far, I set it down using a jackstand on the side and rehooked on the rear lifting hook. This actually wasn't quite right due to Geometry and things were hitting between the intake and the cherry picker, but I got it out eventually. Just remember that the transmission always has to be tipped down until it clears the firewall.

I set the assembly on three jackstands under the engine (After reinstalling the motor mount) and removed the transmission. I then picked up the engine and bolted on the spider for the engine stand. Be sure you don't bolt to the oil pan holes. After the spider was on, it slips right into the engine stand. I have seen dealer techs struggling with bolting the spider to the engine while the spider is still on the stand. This is silly. Take it off, bolt it on, then slide it in.

Next installment is head removal. Or as the French kings would say, "Divorce".
 

whitedog

New member
Head is off.

Slight scoring there on the walls. I can barely feel it with my finger and can't really catch it with my nail. I can actually still see the cross-hatch marks in the scored areas.
 

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sailquik

Well-known member
Hmmmm....
The hole and radial crack in the top of the piston looks a bit ominous.
The bore looks pretty good.
Ask Dr. A to take a look.
You can probably just replace the piston and rings.
Maybe a minor hone job on the #5 bore.
If all the other pistons look good, probably just replace
the #5 with the hole in it.
Maybe Dr. A can provide us with an idea of what may have
caused the hole in the piston...... too much fuel/hydrauliced...
not enough fuel and burned through......what?
Roger
 

whitedog

New member
The odd part is the shape of the hole. It is flat against the crack, but rounded on the other side. It's like the burning went as far as the crack, then the crack stopped the heat from expanding the hole. But this would happen only if the crack occurred first and Dr. A says these pistons don't crack. That points to the hole starting and causing a stress riser that caused the crack, so why isn't the hole on each side of the crack?

The crack only extends to not quite the center of the piston and all the way down to the wrist pin.
 

Dingo

New member
Have seen similar on other engines when the gudgeon pin (wrist pin ) was incorrectly fitted . It caused a stress point & eventually the fracture to open . The missing piece blew out under the pressure of combustion . May i suggest that you look to see if the crack lines up with the wrist pin area , you might have a case to ask MB to repair your engine as this was most likely caused during assembly .

You might be p*ssing into the wind but it has to be worth a try , if the engine has never been apart since it was built you should be able to pass the buck to Mb engine builders

If you do rebuild it yourself , hone ALL the bores & fit new rings to each piston .

Best of luck with it :)
 

whitedog

New member
Have seen similar on other engines when the gudgeon pin (wrist pin ) was incorrectly fitted . It caused a stress point & eventually the fracture to open . The missing piece blew out under the pressure of combustion . May i suggest that you look to see if the crack lines up with the wrist pin area , you might have a case to ask MB to repair your engine as this was most likely caused during assembly .

You might be p*ssing into the wind but it has to be worth a try , if the engine has never been apart since it was built you should be able to pass the buck to Mb engine builders

If you do rebuild it yourself , hone ALL the bores & fit new rings to each piston .

Best of luck with it :)
Do you think that I will need to pull the crank to hone the cylinder(s)? And if the crank is in place, do the squirters need to come out?
 

talkinghorse43

New member
Pics of the top surface of the piston look a little like those posted some time back by Waynerodd of his own van that suffered overheating of a cylinder due to either loss of an oil squirter or a stuck open injector. Anyway, seems to me overheating (burned piston) of the piston could cause the damage shown.
 

whitedog

New member
Pics of the top surface of the piston look a little like those posted some time back by Waynerodd of his own van that suffered overheating of a cylinder due to either loss of an oil squirter or a stuck open injector. Anyway, seems to me overheating (burned piston) of the piston could cause the damage shown.
Oil squirter, eh? that's a good suggestion. from what I see, the squirter is angled slightly towards the front of the engine so the oil flow would be CCW as viewed from the top so the area where the crack occurred would be the last to get oil. If the oil flow is low out of that squirter, that part of the piston would be hottest causing the crack.

So do I need to pull the crank to R&R the squirter? I know the book says to, but what do I really need to do?
 

whitedog

New member
Talking with some other folks in town, I have come up with a few other ideas and thoughts.

The thoughts about the oil squirter not flowing enough oil seems good on the surface, but I think the piston should be showing signs of discoloration and it isn't. The scuffing in the cylinder is in line with the wrist pin and this is not typical of overheating. Typical four corner scuffing from overheating is just outside of the pin bosses rather than centered on them.

I am more and more sure that the hole is a chunk rather than a burned hole. Supporting this is a Ford piston I just looked at that has a hole all the way through to the rings and not only is the shape of the hole different, but that hole took less than a 1/4 mile to go all the way through and this hole only goes to the oil galley underneath after 20-30 miles. Also the edges of it are rough rather then melted appearance of a burned hole.

This leads back to what Dingo mentioned about his experience with the gudgeon pin being incorrectly installed. That being said, I don't see anything in the wrist pin bores that indicate anything but Love during installation.

:idunno:
 

jdcaples

Not Suitable w/220v Gen
When this is over, don't forget root cause analysis.

I don't want my engine to die on me like that, so if I can prevent it, I'll go to great, economically dubious lengths.

-Jon
 

whitedog

New member
I have spent all morning talking with people about failure analysis and it what most of these post are about. I will be sure to share any conclusion that I come up with. I still would like some additional, real life information on the oil squirters. I have PMd Dr.A and Wayne but haven't heard back from them as of yet.

Attached is another picture without the O-ring pick in the way.
 

whitedog

New member
Let me try the picture thing again.

Something I just thought about is that the round surface had carbon on it. Typically a streaming injector would be washing that area and cleaning it, washing away the soot. Also the heat required to melt the piston wouldn't allow that soot to build there, would it?
 

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Aqua Puttana

Poly - Thread Finder
Let me try the picture thing again.

Something I just thought about is that the round surface had carbon on it. Typically a streaming injector would be washing that area and cleaning it, washing away the soot. Also the heat required to melt the piston wouldn't allow that soot to build there, would it?
Ths picture is much better. That said, is there definte signs of melting? The edges of the hole look pretty sharp. Maybe an inclusion caused a weak area which finally failed? It's tough tell anything from a picture though. vic
 

whitedog

New member
Ths picture is much better. That said, is there definte signs of melting? The edges of the hole look pretty sharp. Maybe an inclusion caused a weak area which finally failed? It's tough tell anything from a picture though. vic
Vic, you are the third person I have talked to that mentioned an inclusion. The only way to know for sure would be to break apart the piston somehow. I have some carb dip I could use to clean things up really good and maybe see the surface in there better.

It's certainly possible, it would just seem odd that the inclusion was directly over the gudgeon pin.I still want to break it apart, but I don't have any good ideas on how to do that.
 

sailquik

Well-known member
Whitedog,
Find someone with a band saw (fine plade for aluminum) and saw it from the other side in precise alignment with the crack.
Then saw up the skirt on the carcked side and you should be able to see the failed area quite well without any saw marks to mislead.
Don't saw into the crack or the hole....leave those alone. Might have to use a wedge or
two to break it apart.
Roger
 

Aqua Puttana

Poly - Thread Finder
I don't want my engine to die on me like that, so if I can prevent it, I'll go to great, economically dubious lengths.

-Jon
One of my jobs in past was making vanadium aluminum which was used in the manufacture of jet engines. I believe it was specifically for the turbine blade assemblies. Each lot of 1/4 x down size metal was x-rayed to screen out contaminants before being shipped in special drums. Maybe you can order custom pistons from Lockheed?

Seriously though, any inconsistency in metal can cause weak spots and a potential failure area. An inclusion of any type will do it. Vic
 
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whitedog

New member
One of my jobs in past was making vadium aluminum which was used in the manufacture of jet engines. I believe it was specifically for the turbine blade assemblies. Each lot of 1/4 x down size metal was x-rayed to screen out contaminants before being shipped in special drums. Maybe you can order custom pistons from Lockheed?

Seriously though, any inconsistency in metal can cause weak spots and a potential failure area. An inclusion of any type will do it. Vic
Vic, would the aluminum of those pistons show discoloration from heat? I was thinking of steel that would get blue, and I don't see any of that, but I'm not sure that I would with the Aluminum.

I did notice some yellowing on the bottom that could be from oil that got hot there and turned yellow. This is the only sign that I have seen to indicate excessive heat.

To open the crack, I could cut it horizontally at the wrist pin, then vertically at the piston crown to meet the first cut. This would slice out the cracked section and it could easily be broken open. But is there steel supports in the ring lands? I haven't cleaned it up enough to tell.
 

Aqua Puttana

Poly - Thread Finder
Vic, would the aluminum of those pistons show discoloration from heat? I was thinking of steel that would get blue, and I don't see any of that, but I'm not sure that I would with the Aluminum.

I did notice some yellowing on the bottom that could be from oil that got hot there and turned yellow. This is the only sign that I have seen to indicate excessive heat.

...
My experience with aluminum in gas engines, industrial equipment and electrical equipment is that aluminum subjected to heat doesn't discolor like steel does. There may be some black coloring around the area of the actual high heat or melting, but not necessarily an obvious color change like steel. Whether that experience transfers over to diesel pistons... :idunno:

The yellow coloring could be from fuel or oil, but I defer to anyone with diesel experience. Sorry I can't offer more. vic
 

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