Melted Piston

[SUBVET]

Gentlemen,



I was hoping to get some of your expert opinions on my predicament. I was proceeding up a grade , pulling a light trailer (approx 1500#) and watching my gauges (Pyro aprox 1000-Pre turbo) at which time I started to hear a ticking sound. As I pulled to the shoulder the engine shut down. I also noticed that at this time the coolant temp gauge was pegged I then checked the upper and lower hoses and noticed no obstructions. All attempts to restart failed and the vehicle was towed to a dealership. When the CTD was pulled down it was determined that #4 piston had melted on the top of the piston. My mechanic stated that he had never seen anything like this before. Iwould greatly appreciate any ideas and or recommendations on this matter. All modifications are listed in my signature.



Respectfully submitted,



Rob Burns

 

[Rammin On]

Most likely a bad injector ...

 

[SLang]

1) Stuck injector may do this.



2)The piston have oil sqiured on them from the bottom to cool the piston. This may have been clogged.



3) If you have had you Pyro above 1300 F before, the piston may have been burnt before and something else caused the problem.

 

[SUBVET]

Thanks,



Have had gauges installed since before starting mods, and have made the Pyro my main concern. Temps have been close to but never over 1300 deg. The rest of the cylinders appeared to be normal upon inspection.



THANK YOU,



Rob

 

[Dan_69GTX]

Hey Slang and Rammin On -



Why would a bad injector do this??



By bad to you mean not atomizing the fuel properly or by being stuck open or ??



Thanks!

Dan

 

[Cummins Corvette]

Are you still on the stock injectors? How many miles are on the truck?

 

[Rammin On]

They could be stuck open ... leaking ... weak ... . tip damaged . . just pouring {so to speak} fuel in the cylinder .....



Piston cooling nozzles that get clogged are another item to look at ...

 

[SUBVET]

Yes still injectors are still stock and she now has 56,454 for mileage on her.



Rob

 

[BCFAST]

I would guess a clogged, or not-openning injector. This would cause the cylinder to run lean (dry) and VERY hot.

 

[LSMITH]

An injector that was clogged or not opening would make that cylinder very lean and it would run cold, not hot. There is no way to burn a piston with too little fuel in a diesel. An injector that was dribbling or stuck open will burn a piston. The fuel will pool in the crown and burn on the surface, when it does this the boundary layer is compromised allowing full heat transfer to the piston. The boundary layer is what prevents this in a normally operating engine. More than likely it was an injector that was stuck open or dribbling fuel that caused the meltdown.

 

[Dan_69GTX]

Thanks for the explaination!



Is the only way to tell if this could be happening on an engine is to check the temp of the exhaust manifold at each cyl w/ an infrared temp gun? Or are there other ways?



Dan

 

[BCFAST]

OOPs!! sorry... I'm thinking about my own experience with a gas race motor... my mistake... and thanks for the education!

 

[LSMITH]

Dan, I think it would be too late for you to tell if it happened. It would also happen under load, a thermal gun is useless in that situation. A pyro for each cylinder might catch it in time, but is not really practical. It will burn down in a very short period of time too. The odds of this happening to me or you is miniscule IMO, just plain bad luck or poor maintenance letting junk into the injection system would be needed for this to happen. I am not saying that SUBVET did not take good care of his truck, only that it is one possible cause. One more reason to not fill your filter with unfiltered fuel IMO also.



I also think that quite possibly the EGT for that cylinder can be in the normal range while the fuel is burning in the piston crown, the heat transfered to the piston could be high enough to damage it without a high EGT warning. I think a comparitive reading to the other cylinders would be needed to see the difference. I have no proof of this, it is just my gut feeling on it.



A thermal gun can detect imbalances in the cylinders though. I have done it and seen about a 40* difference between cylinders under no load and 2500 RPM, with #1 being the hottest and #2 the coolest on mine. #6 was also hotter than the middle cylinders. What to do with the information you gather with a thermal gun is a problem too, the value of the information gathered is not really known. If you lucked out and caught it at the perfect time you might benefit from the thermal checks.



LOL@BCFAST, we all still have gasser lapses once in a while!!!

 

[SUBVET]

Just for the record, Oil was changed every 3-5K, Filters from Fleetpride and fuel filter was never prefilled (normally thought that I would pump my thumb off).



transmission was rebuilt last fall at approx 47K (THANK YOU DTT)



The rear end in my CTD had a slight gear noise from get go(Sonar training). Taken to multiple Dodge dealers who stated that for the most part that they could hear it on the road but "could not duplicate it" in the shop. It blew at 53K. They were nice enought to tell me that because of multiple failures many warranties had been extended to 48K BUT.....



Murphy's (Law) and the Burns family have been mates forever.



Hope that this clears things up some.



Again THANK YOU for all replies! !



Respectfully,



RJB

 

[LSMITH]

SUBVET, I hope I didn't offend you, I certainly never meant to insinuate that you did not take good care of your truck. Your maintenance routine sounds positively anal like the rest of us .



I also know Mr Murphy on a first name basis , sometimes I think he is glued to me.



Your case is a good example of failures under ideal conditions, it can and does happen every day unfortunately. I hope you have better luck in the future.

 

[SUBVET]

LSSMITH



NO OFFENSE TAKEN.



I know that everyone is different to a degree. I just wanted to try to supply the best info that I could for my problem. You cannot make a proper diagnosis of a problem without the facts relating to same.



Maybe this will in some way help someone else in the future.



THANK YOU AGAIN for your reply.



Respectfully,



Rob

 

[Turbo Thom]

For what its worth, the shop forman at work said to much fueling on the 5. 9 engine will cause much heat and when the fuel is injected the top of the piston will actually blow out. True or not, I don't know. The business is crane rental. Most of the engines, about 90, are ISC Cummins. There are 7 Rams for service trucks. Then there's mine . The prettiest of all Not a service truck.



The owner of the place just bought a Provost Motor Coach with a 600 HP Detroit. That thing will "fly"



. . Preston. .

 

[illflem]

Here's a thread with a different theory and some ugly pictures https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=33387&perpage=10&pagenumber=1

 

[David Oxland]

lPossibly an injector not performing allowing fuel impingement on the piston top. Fuel is meant to be burning on it's way across the cylinder, not as it touches cylinder walls or piston top.



One thing that it's important to understand is that diesels cannot run too lean. They always run full lean unless just plain overfueled. Except for a few which have the barometric type governors they all run full lean(meaning maximum air available). Power control is achieved strictly by restriction of fuel. No cooling process is achieved by excess fuelling. This thinking comes from the gasoline burning fraternity.



Perhaps someone could promote a little more discussion along these lines. But a diesel running lean or too lean is really faulty thinking.



Sorry to be blunt I just don't know any other way to put it.

David

 

[P Madrid]

Was your inj damage on that cyl? If there was no damage, have a pop test done, test the rest of them while you're at it. If it's stuck open it will drip right away and many times it will also allow compression to leak back to the P7100 causing all kinds of problems. It souds more like it was dripping, opening to soon. When there's a problems with an oil cooling nozzle you see damage from below the piston and not much on top