Piston Rings Worn Out, Time for a Rebuild

[Wildchild467]

Just saw your piston post in the parts wanted section. Everything ok?

Yea, so far so good. I put the same pistons back in after I honed the cylinders. If it was a glazing issue, that would have fixed it. If its a ring issue, then we will soon find out.

 

[Wildchild467]

This weekend I got the turbo on and related parts. Coolant is in, zip tied wires and made sure everything in secure. Also installed transmission tunnel from when I changed the clutch. Things are starting to come together. I think all that is left to do is change the fuel out to 100% diesel and see what happens. The first time i fire it up will be on the dyno. Ill make sure I don't have any leaks and then start it running the 15 hp load for 30 minutes per the manual and break in procedure. It increases in load of course, but it starts at 15 hp.

Here is picture of it as it sits in the garage from this weekend. not shown is the air cleaner-to-turbo intake pipe and air cleaner on the truck (but it is on there now).

 

[Jeepsinker]

With the difference in ring tension you found, I believe I would have gone back in with a new set of surplus multifuel rings on the new pistons, especially with all the labor time you have in it. That's just my thought on the matter. Ring tension in a high compression engine is certainly important. My best guess is that those pistons and rings are for an 80- 90, or maybe even a 120 horse White tractor engine, which of course would have lower cylinder pressures, thus not needing as high of ring tension.
If you still have issues after proper break in, then there is your culprit.

 

[o1951]

Can't wait to learn how it turns out. Never had the luxury of a dyno break in.

 

[Wildchild467]

With the difference in ring tension you found, I believe I would have gone back in with a new set of surplus multifuel rings on the new pistons, especially with all the labor time you have in it. That's just my thought on the matter. Ring tension in a high compression engine is certainly important. My best guess is that those pistons and rings are for an 80- 90, or maybe even a 120 horse White tractor engine, which of course would have lower cylinder pressures, thus not needing as high of ring tension.
If you still have issues after proper break in, then there is your culprit.

I got a quote for the rings and they were about $80 per cylinder for the "NOS LDS Piston Kits". Rings for a standard LDT multifuel are $10. This is why I was looking for good used LDT pistons. Anybody that has blowby and wants to rebuild theirs, I suggest looking at their pistons real good to make sure the ring surfaces are good and then just put new rings in it. Knowing what I know now, that is what I would have done if my LDT pistons were in good shape.

 

[Wildchild467]

Can't wait to learn how it turns out. Never had the luxury of a dyno break in.

It takes a lot of time. It might be an 8 hour activity. I figure the truck will be running on the dyno for about 6 hours and at some point after the 15hp light load in the beginning, I'll want to retorque the head just because I can... and re-adjust the valves.

 

[cattlerepairman]

I'll want to retorque the head just because I can... and re-adjust the valves.

In order to re-torque the heads, the valve train has to come off anyway, correct? Would removing/replacing the valve train not automatically require valve re-adjustment?

 

[Another Ahab]

I got a quote for the rings and they were about $80 per cylinder for the "NOS LDS Piston Kits". Rings for a standard LDT multifuel are $10. This is why I was looking for good used LDT pistons. Anybody that has blowby and wants to rebuild theirs, I suggest looking at their pistons real good to make sure the ring surfaces are good and then just put new rings in it. Knowing what I know now, that is what I would have done if my LDT pistons were in good shape.

That's a REAL big "delta" in the cost. What's the difference in expense all about:

- Is it the quality of the steel or something?

 

[gimpyrobb]

That's a REAL big "delta" in the cost. What's the difference in expense all about:

- Is it the quality of the steel or something?

...and did you measure the pistons to see if you could put the LDT rings on the LDS piston?

 

[74M35A2]

I would have done new rings also, given his compression readings were all over the map and he found erratic ring tension in the rings he pulled out. He instead went for a NOS turbo for nearly the same amount. Maybe that will make up for the blow by. I would have done the new rings, made sure the engine ran correctly on 100% diesel fuel, and then rebuilt the existing turbo if all was well. If the engine still didn't run right, then out it comes and in goes something fun like a wicked up 400hp/4000rpm 5.9L or 6-71T Detroit. He really enjoys his free fuel though (WMO), so he is trying his best to retain that feature. He has nearly $800 hanging off just the outside of the engine in a new clutch and turbo. It has no excuses to not be the best running truck at the Ohio meet, unless the rings are out to lunch.....(play scary music here).

 

[74M35A2]

It takes a lot of time. It might be an 8 hour activity. I figure the truck will be running on the dyno for about 6 hours and at some point after the 15hp light load in the beginning, I'll want to retorque the head just because I can... and re-adjust the valves.

You forgot the 1 hour each way for setup/knockdown, and a usage rate of $125/hr. Bring a bag of cat litter in case your engine goes exothermic.

 

[o1951]

a usage rate of $125/hr. thermic.

Are you NUTS, Wildchild?
You going to blow $800 on dyno charges to break it in?
I thought you were getting use of dyno for free.
You could have bought new rings and just break it in on the road, like everyone else does. Road break ins worked fine for me and other SS members who rebuilt their engines.
For insurance, use Deere break in oil.

 

[74M35A2]

That's heavily discounted. $125/hr is usual dealership single person labor rate. Even a trailer type twin roll Mustang type dyno likely bills out at more than that. The one he is using is an EPA approved in-floor single 48" roller with > 1% accuracy across the operating spectrum. Our usual charge is $600/hr. If he agrees to paint the back half of the 923A2 "trailer" I am making for my 925A2, including materials, then I'll fully excuse all dyno facility and labor charges...... I don't mind giving up a day for him, but not playing with my kids for a day? He is going to have to pay for that.....

 

[skinnyR1]

This thread is becoming painful to read, and I feel for WildChild. It is potentially leading to a train wreck conclusion after so much money and time has been dumped into it, and everyone is already giving their 2 cents upon reflection and hindsight, on what should have been down. I see it as us all kicking Wildchild every step of the way on mistakes or what ifs, and the miserable conclusion is lurking next......

I hope and wish the best for your efforts Wildchild, I am sure I am speaking for the whole audience here if it hasn't been said by others.

 

[WillWagner]

It takes a lot of time. It might be an 8 hour activity. I figure the truck will be running on the dyno for about 6 hours and at some point after the 15hp light load in the beginning, I'll want to retorque the head just because I can... and re-adjust the valves.

6 hrs!!?? Who told you that? The rings will be seated in 45 min. If you used new style gaskets...like FelPro, Mr Gasket, etc, with the fire ring crimped to the gasket, no retorque is needed.

I run the dyno every day so, yes I know what I am talking about

 

[Wildchild467]

...and did you measure the pistons to see if you could put the LDT rings on the LDS piston?

Yes and they were different.

 

[Wildchild467]

This thread is becoming painful to read, and I feel for WildChild. It is potentially leading to a train wreck conclusion after so much money and time has been dumped into it, and everyone is already giving their 2 cents upon reflection and hindsight, on what should have been down. I see it as us all kicking Wildchild every step of the way on mistakes or what ifs, and the miserable conclusion is lurking next......

I hope and wish the best for your efforts Wildchild, I am sure I am speaking for the whole audience here if it hasn't been said by others.

Thank you. I'm just doing my best over here. Trying to document everything as much as I can and follow the manual for all the specs. If I see something that might cause issues, then I try to go after it and fix it... hence the new turbo. The compressor wheel was shot and if its not putting out the right amount of boost maybe that will make it not run as well or something. If I didn't replace something and I knew it was bad, somebody would tell me replace it. If I didn't replace it, I would have somebody telling me that I should have. I just try to explain the best I can what I'm doing so everybody can see the process and comment on what knowledge they have. We all come from different backgrounds and I value EVERYONES input.

 

[Wildchild467]

6 hrs!!?? Who told you that? The rings will be seated in 45 min. If you used new style gaskets...like FelPro, Mr Gasket, etc, with the fire ring crimped to the gasket, no retorque is needed.

I run the dyno every day so, yes I know what I am talking about

I looked in the manual for the break in for an engine with new pistons and sleeves. So i was just going by that. I think the manual states the whole test was something like 5 hours. I figure time in between doing things, set up and tear down of putting the truck on the dyno... it all takes time.

I was told you were a guru with the diesels, thats why I PM'ed you. I appreciate your help!

What is your suggestion on breaking in the engine on the dyno? Plan is now to towbar it to the dyno and strap it to the down. When it is strapped down, thats when we will fire it for the first time. I hear suggestions like some guys start them up, let them warm up and check for leaks for 3 or 4 minutes at a high idle and then put it under the heaviest load you can get. Now i don't have any diesel break in experience so I was just looking to follow the manual thinking it worked back then, so it must work now. Buuuut, that was then and this is now. Oils and materials change, etc which can effect the break in. What do you think we should do for the test/break in procedure. Thanks again for your input. Sorry if I ask a lot of questions. I just like to learn from people and take in what they have to say. I like knowing how things work and I think I know about how every part of this truck works. Scary! haha!

 

[Wildchild467]

I would have done new rings also, given his compression readings were all over the map and he found erratic ring tension in the rings he pulled out.

When did I say I had erratic piston ring tension with the rings I pulled out? I don't think I ever did because I didn't. (that sounds like I am mad, but I do not mean it to be. just trying to clarify)

All of the new style LDS piston rings seemed to have the same ring tension. It was less tension than NOS LDT piston rings, but they were all the same. All the way from the cylinder with 95% leak down to the one with 15% leak down. I didn't actually measure then with a force gauge, but they all felt the same. I also did that test where I put a ring in each cylinder and put a piston on it with no rings. The new style LDS piston rings could not hold the piston up, yet the NOS LDT rings could hold the piston up from falling through the cylinder. I only used one compression ring for the test. one from the new style LDS piston rings and one piston ring was from the NOS piston rings.

 

[Jeepsinker]

That's why I was saying I would have used the new LDT rings. More tension is better, especially since you have less rings anyway with the new pistons. I don't feel like those pistons are right for our engines. I'm thinking they are for another application, but since they fit, the dealers are selling them anyway. I doubt they care how well they work as long as they get their money.