Are CR's prone to breaking rings

I just today pulled down an '05 that had an intercooler blow up and the guy kept forcing it to make it home.
This thing go so hot it MELTED a hole in the exhaust manifold near where the 5th and 6th exhaust ports join together. There is a gaping crack there.

The guy said he replaced the engine after he put the intercooler in the truck, because the engine had "a schit ton" of blowby.

Okay, fine. So I pulled the head off it to-day fully expecting a totally fubar-ed #6 piston, scored cylinders and the whole works and I found...NOTHING!
Piston tops look GREAT, no globs of aluminum missing, no cracks in the stepped area, no scores in the cylinders, nothing loose, just NOTHING.

I suspect broken rings, because if you turn it over there are "marks" in the #6 cylinder wall that wipe off with a rag and there are hone marks in the same area and no more marks after I wipe it off.

I've looked at all 6 holes and nothing stands out for damage, save the possibility of broken rings.
Was this probably one of those "lucky" engines?

Mark.
 
Me too. I'd kinda like to know the cause of all this myself.

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I've got 321k miles on my 03 and knock on wood.....I've never done anything to the engine except set the valves and replace the injectors.

When the time comes I have a fully assembled head from an 06 that I grabbed for $200 that will find its way on the top end!!!!! :)

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TX_5.9 said:
I've got 321k miles on my 03 and knock on wood.....I've never done anything to the engine except set the valves and replace the injectors.

When the time comes I have a fully assembled head from an 06 that I grabbed for $200 that will find its way on the top end!!!!! :)

Sent from my XT1080 using Tapatalk
Click to expand...

If there is ANY one cummins common rail that WILL make over 300k, it's the 2003-early 2004 engines, they are the "mule" of the series, IMO.

If you've ever tried to physically break a Cummins ring, you'll understand why the rings breaking in these engines is an interesting problem.
They are VERY difficult to break, it takes some serious twisting and bending to do it.
They aren't like your OEM 350 chevy rings. ;)

Personally, I believe it's heat related, be it from fueling them hard, or from coolant or cylinder temp related issues.
The same holds true for the seats dropping, chances are that if this happens, at some point the engine has been very warm in some way or another.

Rings are like any other steel based item, in that they have "temper" which makes the springs have tension. It's what makes springs do their job.
Heat them up just to the the point of a mild glow and that usually takes the temper out of them, then you either have a buttery, easily bent metal, or you have a fragile, easily broken one.

Temper is achieved by a number of different cooling methods, by slowly dropping temps, or by quenching using different liquids or chemicals at certain temperatures to quench iron-based products, or other means.
Bring this metal near it's melt point and hold it there for long periods (or even short periods) where it's cooled quickly and repeatedly and chances are the temper will be affected.

But that's just my observation, from a non-educated standpoint.

As far as seat rings dropping, in MY opinion, the seat rings dropping are no less than ill-fated engineering, with heat being the deciding factor.
I've never been a fan of a CAST IRON seat ring in a head that is itself CAST IRON.
It just seems counterproductive to just using a STEEL seat ring instead.

The IDEA of a seat RING in a head,\ is to cut down on the inherent problem of cast heads, with induction hardened parent material seats, cracking.
This works, providing you don't use inferior materials, such as thin-cast seats, which was the case in the early common rails and some VP engines.

Sorry for the rambling post. :D

Mark.
 
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I have taken apart many later cr 5.9's and ALL of them have always had broken rings on #1 and #6 cylinders. The top ring will be broke in half, but there is usually no damage to the cylinder wall surprisingly, but that is my experience with them so far.
 
Mark Nixon said:
If there is ANY one cummins common rail that WILL make over 300k, it's the 2003-early 2004 engines, they are the "mule" of the series, IMO.

If you've ever tried to physically break a Cummins ring, you'll understand why the rings breaking in these engines is an interesting problem.
They are VERY difficult to break, it takes some serious twisting and bending to do it.
They aren't like your OEM 350 chevy rings. ;)

Personally, I believe it's heat related, be it from fueling them hard, or from coolant or cylinder temp related issues.
The same holds true for the seats dropping, chances are that if this happens, at some point the engine has been very warm in some way or another.

Rings are like any other steel based item, in that they have "temper" which makes the springs have tension. It's what makes springs do their job.
Heat them up just to the the point of a mild glow and that usually takes the temper out of them, then you either have a buttery, easily bent metal, or you have a fragile, easily broken one.

Temper is achieved by a number of different cooling methods, by slowly dropping temps, or by quenching using different liquids or chemicals at certain temperatures to quench iron-based products, or other means.
Bring this metal near it's melt point and hold it there for long periods (or even short periods) where it's cooled quickly and repeatedly and chances are the temper will be affected.But that's just my observation, from a non-educated standpoint.

As far as seat rings dropping, in MY opinion, the seat rings dropping are no less than ill-fated engineering, with heat being the deciding factor.
I've never been a fan of a CAST IRON seat ring in a head that is itself CAST IRON.
It just seems counterproductive to just using a STEEL seat ring instead.

The IDEA of a seat RING in a head,\ is to cut down on the inherent problem of cast heads, with induction hardened parent material seats, cracking.
This works, providing you don't use inferior materials, such as thin-cast seats, which was the case in the early common rails and some VP engines.

Sorry for the rambling post. :D

Mark.
Click to expand...

This
 
No
Snedge said:
You know what breaks rings? Heat resulting from dirty air filters, boost leaks, tuners. I've seen it more in trucks that had to work for a living. The HPCR fuel system expanded the window for failure due to incomplete combustion.

If I had to guess, I'd say it has something do with Cummins engineers needing to turn up the wick on exhaust temps to burn off NOx with the strict emission standards looming pre EGR and DPF on the Dodge.

NOx - Wikipedia, the free encyclopedia
Click to expand...

Exact same thought I had. Air flow/incomplete combustion issue and a hot tune for a mid duty.
It isn't just Cummins breaking rings in the 300hp arena.

Are the engines described from manual or auto applications or both in most cases?
I'm curious about peak cylinder pressure being a culprit.

Monkey Fist Rage
 
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That quench is easy to cause in the cylinders. Foot down on the throttle pouring the fuel to the motor then lifting off taking the fuel away drops cylinder temps quickly.
 
I did three things I hope will help the issue.

1. Milled of the stock intake on the head and replaced with ZZ customs. (The intake ports on the #1 and #6 are tiny on the stock design.)

2. bigger valves and proted valve bowls.

3. coolant bypas from the back of the block freeze plug.

Now I just need to drive it another 175K to test...
 
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Agree with what Snedge said plus the factory ring gaps are too tight. Why? Emissions? EPA? Loosen the gaps up and move on.
 
I will be putting a new set of pistons in
my truck this summer, called Tim Barber
asked what I should make top ring gap
was told .025.
 
to disturbed..

the op of this thread.. yes, a CR can break rings.. we just went through it, and rebuilt a motor that had broken rings... PM Me your email address and ill send pics of the carnage if you would like...

fwiw, truck had just under 150K miles, but it is a work truck...
 
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