FCA or Hole in piston?

[ata]

If you put that head back on without checking that piston I don't think your going to be a happy CAMPER when you fire it up. That fire ring broke between the 5 and 6 cylinders and you say only number 6 was smoking. That would tell me that the head gasket was still holding and you have a ring problem. HOPE I'M WRONG and everything works out.

 

[Cummins724]

If you put that head back on without checking that piston I don't think your going to be a happy CAMPER when you fire it up. That fire ring broke between the 5 and 6 cylinders and you say only number 6 was smoking. That would tell me that the head gasket was still holding and you have a ring problem. HOPE I'M WRONG and everything works out.

The fire ring was missing a chunk, but not broken through. I don't think its a ring problem. The valves were wet around the seat with oil. I'm thinking we have a problem with the head.

 

[MMeier]

I'd be pulling that piston out and have a good look at it. Buddy of mine here had a similar problem and after a little thought he pulled it down completely and found some real serious damage inside. One piston was almost ground smooth and you couldn't see the ring lands. Doubt yours is that far along but since you have it this far ... .

 

[HBarlow]

I'm not a mechanic but it seems to me that sending the cylinder head out for inspection and machining is only doing half an inspection while overlooking several more important ones. If you're doing the labor you're only risking lost time and another cylinder head removal. If you're paying for labor you may just be running up your bill.

I would remove at least #6 piston for inspection.

 

[Cummins724]

If the problem isn't in the head, we are going to be pulling the engine & #6 hole will be getting new sleeve & rings. I'll try to talk my brother into pulling the oil pan, but I honestly think the head is the problem.

 

[Scrappy]

by looking at the last picture there is something wrong with the piston. the spot i am refering to s @ 12 o'clock in the picture. I have seen a piston that looked decent from above but had burned thru @ the first ring. You really need to pull that piston!

 

[rscurtis]

I made my comment about stuck or broken rings by looking at the discoloration near the top of the cylinder. That area should be polished just like the rest of the cylinder. The fact that it isn't indicates that there is no ring contact in that part of the cylinder.

 

[Cummins724]

by looking at the last picture there is something wrong with the piston. the spot i am refering to s @ 12 o'clock in the picture. I have seen a piston that looked decent from above but had burned thru @ the first ring. You really need to pull that piston!

The spot you are referring to is a shadow from oil sitting on the piston where we didn't wipe it off well. In person, all of the pistons/cylinders look great except for that one scratch in #6. I told my brother that we are gonna have to pull that piston to be sure & he said that it sounded like a good idea to him. It is his truck, but I'm gonna talk him into doing it as soon as we here from the machine shop.

 

[Cummins724]

I made my comment about stuck or broken rings by looking at the discoloration near the top of the cylinder. That area should be polished just like the rest of the cylinder. The fact that it isn't indicates that there is no ring contact in that part of the cylinder.

All of the cylinders have that mark on them. They all looked the same?

 

[cerberusiam]

Check your injector tips also, from the looks of the spray patterns on the piston in the last picture it looks like you have 2 holes that are spraying outside the bowl. That will make it smoke a lot more and might be the root of your problem.



The way the one at the top runs towards the lip of the piston would concern me greatly. Might be a ring problem or even piston problem on the side just waiting to blow up.

 

[Cummins724]

Check your injector tips also, from the looks of the spray patterns on the piston in the last picture it looks like you have 2 holes that are spraying outside the bowl. That will make it smoke a lot more and might be the root of your problem.



The way the one at the top runs towards the lip of the piston would concern me greatly. Might be a ring problem or even piston problem on the side just waiting to blow up.

Tips were flow tested & installed on new bodies, same problem. I think I've finally talked my brother into checking the pistons. Here is his latest post from another site.





Theres was some carbon on#6 and the rest were clean. I am hoping valve guides or seats or something small. I think I am going to drop the pan and pull out 5 &6 this weekend to see for sure that nothing is wrong with rings or anything before all the work of putting the head back on. Thanks guys for the help.

 

[Cummins724]

Verdict is in. Head checked out good, actually the guy said it was the best looking CR head he has ever seen with 100k + miles. Pistons are coming out of holes 5&6 tomorrow. I'll post results.

 

[Cummins724]

Broken compression rings on 5 & 6. Anyone ever hone a cylinder & change rings on 5 & 6?

 

[dan.poitras]

It has been done, but check your rings lands very carefully. With broken rings I would most certainly replace the piston affected .

 

[HBarlow]

If it was mine and I planned to continue driving it another 100k miles or more I would pull and have a machine shop or skilled Cummins rebuilder inspect all six pistons.

A partial repair might turn out to be a disappointment and more expensive in the long run.

If your brother plans to keep repair expense down and sell or trade the truck it might be okay to put new rings on two pistons and hone those two.

I would feel guilty about selling it or trading it that way.

 

[rscurtis]

Good point. How would you feel about buying it that way?

 

[Cummins724]

Slow down guys:-laf..... the truck is our tow rig for our excavating business, no plans on selling/trading. My brother already has all 6 pistons in a box ready to take to the machine shop tomorrow for inspection. I checked them over & saw no signs that pistons were damaged, but he is having them inspected to be sure. He is also considering having them coated while they are out.

 

[Cummins724]

Took the pistons to the machine shop today & all check out fine. Picked up the head & new rings/gaskets. We'll be putting it together this weekend.

 

[HBarlow]

That's good news. You did a lot more work but now you know the condition of the internals and can have confidence you can expect another several hundred thousand miles of service from that engine when it's back together.

 

[dan.poitras]

So what broke your rings? Has your brother been using ether?