Melted piston

[Jnasystems]

Is it ok to run an engine (5.9 cummins) with a piston this bad? There are three that have issues and this is the worst one. Compression was still good on all the cylinders (took the head off because of a valve problem in a different cylinder) but the mechanic wants to pull the engine and replace the burnt pistons.

 

[dodge man]

What year truck? How many miles? It happens a lot on the common rail Cummins, (2003 to 2007?), when the injector sticks open or over fuels and the cylinder gets to hot. This could also be the problem with your valves. The question is, what else is wrong? Its also common when they get that hot that rings will crack and break. Just my opinion, but its time for a rebuild. My experience is based on owning a Cummins but not doing a lot of engine work but reading a lot on the Cummins forums, what ever that is worth.

 

[Snobdds]

The melted piston is the symptom, not the root problem. Like said, an injector stuck open. See if it's the pump or the injector itself.

I would rebuild the motor. That piston will not last long and you'll be in there again.

Live by...it's too expensive to be cheap. And, fix once...cry once.

 

[art]

The piston issue is caused from an injector!!!!! Seen it thousands of times and you might just as well replace them with the injectors! Most pans can be pulled easily and just do an in chassis rebuild with the head being tuned up and a new set of injectors
!

 

[buickanddeere]

Pay me now or pay me later

 

[dodge man]

Also try and get NEW INJECTORS. I've heard its very hard to get truly new ones. Rebuilt ones will often look new and be sold as new. Rebuilt injectors can often be high quality but it sounds like a crap shoot. New injectors also = huge $$$$$. I think were talking 2k.

 

[Bladehauler]

pistons and injectors should be replaced with genuine cummins parts , but since the 5.9 does NOT have replaceable liners , I would pull it and clean up the bores or rebore as necessary.basically full overhaul and be done with it . I run a 2 micron absolute
filter right before the cp3 fuel pump, dirty fuel will cause injectors to wear and stick and the stock filter only filters down to 7 microns on the best filters , 10 micron is the average.

 

[QRTRHRS]

Hmmm, aluminum pistons, no sleeves? Injector issue or not, having had a 5.9 with a few tweaks, I think it's a good reason to run pre and post turbo temp guages.

 

[dodge man]

Aluminum pistons? I didn't think they were but I'm not sure. I think 5.9's can be sleeved but I'm assuming its a harder task than some other diesels that are designed to be replaced.

 

[CJONE]

They are aluminum. Most Diesels have steel reinforcement where needed in the pistons ,ring lands ect. Don't know much about the smaller cummins like the 5.9 but some are "throw away blocks" with no sleeve. You can bore and press a new sleeve in to fix a badly damaged cylinder. Most of your larger engines have either wet liners that seal with O-rings to the water jackets and head gaskets [Cat] or dry sleeve, no O-rings and a sleeve is pushed in to a dry bore and it has a fire ring and head gasket to seal head/combustion chamber [Mack]. In frame it now and fix the problem like the others are saying. The piston is the result of the problem and the new one will look the that in a short amount of time if the problem is not fixed. Diesels aint cheap!!! CJ

 

[Cord]

That or get a Pyro gauge and back off the tune when towing. Frankly, I'd replace the pistons. You probably don't need to get into a full rebuild.

 

[buickanddeere]

They are aluminum. Most Diesels have steel reinforcement where needed in the pistons ,ring lands ect. Don't know much about the smaller cummins like the 5.9 but some are "throw away blocks" with no sleeve. You can bore and press a new sleeve in to fix a badly damaged cylinder. Most of your larger engines have either wet liners that seal with O-rings to the water jackets and head gaskets [Cat] or dry sleeve, no O-rings and a sleeve is pushed in to a dry bore and it has a fire ring and head gasket to seal head/combustion chamber [Mack]. In frame it now and fix the problem like the others are saying. The piston is the result of the problem and the new one will look the that in a short amount of time if the problem is not fixed. Diesels aint cheap!!! CJ

What? There is still a long line of people who purchase a light diesel highway vehicle or consumer level off road machine with the diesel option to "save" money.

 

[QRTRHRS]

What? There is still a long line of people who purchase a light diesel highway vehicle or consumer level off road machine with the diesel option to "save" money.

More likely to "make smoke", etc., etc. LOL!

Anyway, it would be nice to know some history on this particular 5.9? There are plenty of stories about 5.9's going 900k or so miles without a teardown or a replacement. My own only had 250k and as long as I kept the oil 1/2 qt low, would use minimal oil. Fill it to the line and it would blow it out, something I have seen on N14's etc. Excessive exhaust temp is a sure killer from what I know. A little tweaking and that post pyro guage will rise faster than a tach.

As far as throw away's, the 3126, C7 CATS or the DT466's come to mind. Along with the 5.9's, excess idleing will also kill these so called medium duty engines as is shutting down with a hot turbo to soon.

 

[Jnasystems]

Thanks for the suggestions. To give a little back story, I tried to run veg oil in it and within 7k miles the injectors were having troubles. I took them out to be cleaned, but they never were quite right after that. There are performance mods on the engine and the airflow was sub par, but that will be rectified with a new turbo that was installed just before the failure. I have now also replaced all the injectors with remanufactured injectors from scheid diesel. Hopefully those two fixes will solve the problem. An egt gage will also be installed to ensure no further problems.

 

[CJONE]

What? There is still a long line of people who purchase a light diesel highway vehicle or consumer level off road machine with the diesel option to "save" money.

Yep, never understood that. Running a 3/4 ton truck with a turbo engine to get groceries, then complain about their VVT coking up?? Buy fuel at the cheapest mom and pop gas station and ruin the fuel system with algae or at least have to drain and refill and change a bunch of fuel filters?? CJ

 

[r8nger]

DT 466 engines have liners, FYI.

 

[QRTRHRS]

DT 466 engines have liners, FYI.

Thanks, I did not know that. I do know that "severe duty", lol, ie; excess idleing in school bus applications sure can do them in.