Piston Rings Worn Out, Time for a Rebuild

[JasonS]

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Just because I do like to learn or in this case "relearn" I looked in one of my old engine manuals and found this. Yes your right Jason, this time ! I think your still sore from the last "ass wooping" I gave you !
About who likes to argue more you have got to be kinding ! Your like the pot calling the kettle black !
I will hold your hand though as long as it's warm !

Hey, nobody else provides as much entertainment as you do. Til next time, Rusty....

 

[V8srfun]

I have been in the automotive field all my working career and understand I am still young. I do not believe in break in oil or any special break in procedures. Just let the engine heat cycle then change the oil and filter to make shure you get any foreign material out of the engine. Then run it like you would any other day. If it is going to break babying it for the first couple thousand miles is just prolonging the problem. Plus if the rings don't seat within the first hour of run time they will never seat. I know there will be a lot of people say I am a young dumbass that doesn't know my head from my butt but the truth is I have rebuilt my fair share of successful engines and spent many many hours talking to engine builders and they agree with what I just said. Just to drive my point home if you go buy a brand new big rig regardless if you bought it today or you bought it new in 1950 it only got to get broken in until its first full load. We all know big rigs get run at the max from day one on the job and do just fine.

 

[74M35A2]

I believe it has to do with todays machining processes vs yesterdays. The finish they can leave now is nearly the same as a "broken-in" engine, so not much breaking in happening right out of the gate anymore like there used to be. And, they are also reducing the number of things that break-in. I don't think anybody makes flat tappet camshafts anymore, they are all roller lifter or OHC roller follower. That really only leaves the rings left, and with how they can leave cylinder bore finishes now and sprayed on/static applied ring coatings, it is probably mated during the first 3 seconds of engine run time in the plant, before it leaves the factory door. For anybody that thinks their new car has not been run at wide open throttle, your wrong. When a vehicle leaves an assembly plant, it is put on a "rolls" dyno rollers where all functions are checked, including wide open throttle acceleration rate, which indicates engine developed power for proper operation, in addition to all lights, switches, radios, wipers, turn signals, headlight aiming, etc.....

 

[daytonatrbo]

I believe it has to do with todays machining processes vs yesterdays. The finish they can leave now is nearly the same as a "broken-in" engine, so not much breaking in happening right out of the gate anymore like there used to be. And, they are also reducing the number of things that break-in. I don't think anybody makes flat tappet camshafts anymore, they are all roller lifter or OHC roller follower. That really only leaves the rings left, and with how they can leave cylinder bore finishes now and sprayed on/static applied ring coatings, it is probably mated during the first 3 seconds of engine run time in the plant, before it leaves the factory door. For anybody that thinks their new car has not been run at wide open throttle, your wrong. When a vehicle leaves an assembly plant, it is put on a "rolls" dyno rollers where all functions are checked, including wide open throttle acceleration rate, which indicates engine developed power for proper operation, in addition to all lights, switches, radios, wipers, turn signals, headlight aiming, etc.....

Every point you touched on here agrees with everything I've been told or come to learn on my own.

Modern engines require less break-in because the cylinders, pistons, and rings are all manufactured more uniformly. This reduces the need for cross-hatching to break the rings in. That's what its there to do. With more uniform bores and rings, that need is no longer as great.

Also, most european engines arrive at the dealer with synthetic oil in them. That basically requires that they already be broken in. Synthetic oil will glaze the rings on a "traditional" fresh engine build and leave the engine with poor compression for life.

Many also have some sort of electroplated or chemically treated cylinder bore that can't be re-machined in the traditional sense.

 

[V8srfun]

Cross hatch on cylinder wall is from what I have been taught to hold trace amounts of oil for lubrication

 

[o1951]

This is a different situation.

After what appears to be a proper rebuild, using appropriate diesel rated oil( Rotella 15-40), OP found poor compression with 90% leak down and glazed cylinders after 2000 miles.

He plans to use a ball hone to refurbish the glazed cylinders, install new rings and original, well used pistons. No way is this the precision machining and fit today's engines get.
This rebuild needs old school break in.

If I was doing it, I would use John Deere break in oil. No way would I want to chance glazed cylinders again, and have to do that job again. For anyone who does not know, engine in vehicle rebuilds are a real PITA. The John Deere break in oil is specifically designed for used diesel engine rebuilds.

 

[daytonatrbo]

This is a different situation.

After what appears to be a proper rebuild, using appropriate diesel rated oil( Rotella 15-40), OP found poor compression with 90% leak down and glazed cylinders after 2000 miles.

He plans to use a ball hone to refurbish the glazed cylinders, install new rings and original, well used pistons. No way is this the precision machining and fit today's engines get.
This rebuild needs old school break in.

If I was doing it, I would use John Deere break in oil. No way would I want to chance glazed cylinders again, and have to do that job again. For anyone who does not know, engine in vehicle rebuilds are a real PITA. The John Deere break in oil is specifically designed for used diesel engine rebuilds.

Agreed.

 

[Wildchild467]

Here is the thing. If a theory is the break in, why would one cylinder be at 95% leakdown and the one right next to it be at 15% leakdown? That is the part that confuses me.

 

[V8srfun]

Break in will always be a argued subject with many different opinions. No one will ever win a break in discussion that is whi I present my opinion and just let it go.

I in no way intend talk down about any ones opinion or way they do things but simply wanted to share the knowledge I have learned over the short time I have been around.

This is a nice project that is making great progress and I have a lot of respect for the op for tackling such a big job on his own. most people would never be brave enough to take this job on even tho they would be the first to say that it is getting done wrong. (I am not talking about the fellow members here as I know most here are very skilled and more than capable of doing the job) keep doing good work and please continue to keep us updated with the progress.

 

[daytonatrbo]

Here is the thing. If a theory is the break in, why would one cylinder be at 95% leakdown and the one right next to it be at 15% leakdown? That is the part that confuses me.

What valve work has been done?

 

[JDToumanian]

Here is the thing. If a theory is the break in, why would one cylinder be at 95% leakdown and the one right next to it be at 15% leakdown? That is the part that confuses me.

And then there's the 'tink' sound heard when tightening the head... I think something is cracked.

 

[rustystud]

Hey, nobody else provides as much entertainment as you do. Til next time, Rusty....

I'm glad to be of assistance ! Though entertaining comments do belong to "Ahab" . He is the master there !

 

[rustystud]

Here is the thing. If a theory is the break in, why would one cylinder be at 95% leakdown and the one right next to it be at 15% leakdown? That is the part that confuses me.

That is also the thing that I keep coming back to. What has caused that one cylinder to loss so much pressure ?! Was something cracked ? That "tink" sound you heard keeps coming to mind.
We ruled out piston rings. The break-in process would not explain this. The gaskets looked fine.
The pistons are new and the cylinders are also new. The heads where checked for warpage.
The cylinder deck height was correct. The valves where machined. What is left ?

 

[skinnyR1]

Everyone is overlooking the coolant in the valve cover and in the oil. My money is on a crack somewhere whether it be head or block.

 

[o1951]

Everyone is overlooking the coolant in the valve cover and in the oil. My money is on a crack somewhere whether it be head or block.

Agree - see post 250.

 

[74M35A2]

We'll see. It held 7psi cooling system pressure test for several minutes, and the best we can confirm so far is the new rings did not seat. The piston sides show signs of leaking combustion past the rings, especially on the wrist pin opening sides. Compression numbers were low, and leak rates were 15%-95% across the front 3 cyls. If so, that could be pushing a lot of moisture into the oil, since the products of combustion are only CO2 and water (if combustion is 100% complete). The fan is direct drive and the truck was never under a load, so I don't see how even 1psi could have been reached in the cooling system. Tom said the rear head nuts seemed looser than the front. Head gaskets look good on removal, looked brand new. It is taking more head nut rotations than anticipated to reach final torque between the last 2 steps. Unsure if that is the new gasket compressing or the studs stretching.

He ordered a ball type hone, new rings, and new head gaskets. To be reassembled, broken in on diesel, and go from there. Will measure leak down before and after break in to quantify. Yes, there is a lot of moisture in the oil. I don't think any of it was found to be green though.

 

[red]

7psi will not identify any leaks in a cooling system. Must take it up to at least your radiator caps rated pressure, just a waste of time otherwise.

 

[74M35A2]

7psi is the specified rating of the vehicle's cooling system cap.

 

[rustystud]

7psi will not identify any leaks in a cooling system. Must take it up to at least your radiator caps rated pressure, just a waste of time otherwise.

I agree here. Also the part being checked must be at operating temperature. Heat expands the metal, also cracks. I would bring the engine up to operating temp and then try and pressurize the system with at least 10psi. Since you never experienced any coolant loss this is all a moot point.

 

[V8srfun]

I personally have always tested a cooling system by over pressurizing the system by 3-5 psi. Let's be honest if something breaks under that little amount of extra pressure it needed attention any way and all you did was save yourself a future problem. The extra pressure also helps find the leak you are looking for in the first place.