Piston Rings Worn Out, Time for a Rebuild

[rustystud]

But Mark now has the same issues with with his piston kits.... the truck lacks power and is hard to start. He is using 100% diesel.

As far as me using some WMO in my fuel, the first first rebuild I had about 50% diesel and 50% WMO... and it ran good for a while until it started not to and getting blow by and hard to start.

The second "rebuild" I honed the cylinders (incase of glazing) and checked the rings again and all looked just as it did before. I also drained all my my fuel and filters and filled with 100% diesel. I had the same results as before. Still harder to start and had blow-by.

Nobody knows what the problem is and we dont have data to support and root cause, only speculation. The only data I have is doing a leakdown test and finding my "New Style LDS Piston Kits" had 95% leakdown. So if nothing was broken and all looked fine, then what would using WMO do physically do the engine to not cause it to run well? upon visual inspection, everything looked fine inside the engine when it was pulled apart the second time.

I hope to have Mark chime in and see what more his results were.

If my engine bites the dust again, Im going to put a 4-71 Detroit Diesel in it with jake brakes. Enough screwing around. So if anybody has one, I may want one just to have as backup. I love the multifuel but enough is enough after a while.

Your engine problem is a real head scratcher for sure. I cannot remember any similar problem before. Now with two engines having the same problem this is getting real interesting. To bad your not closer as I would really like to look that engine over.

 

[ShawnIfert]

Your engine problem is a real head scratcher for sure. I cannot remember any similar problem before. Now with two engines having the same problem this is getting real interesting. To bad your not closer as I would really like to look that engine over.

i have not had an issue at all other than the cold starts. The compression ratio is about 20:1 with the 5 ton piston kits. But you have to keep in mind that the engine does not have a heating grid or glow plugs. I hit the manifold heat and hold it after it fires and let go of the start button and it is all good. Just like a modern motor on cold start.

But like you you have said Rusty I will like to take a look as well. The new kits have cromemolly rings. They are old kits and the pistons and rings are set in the sleeves. The failure could be do to a loose of spring tension in the rings from being compressed for so long. That is the only thing I can come up with,.

 

[rustystud]

i have not had an issue at all other than the cold starts. The compression ratio is about 20:1 with the 5 ton piston kits. But you have to keep in mind that the engine does not have a heating grid or glow plugs. I hit the manifold heat and hold it after it fires and let go of the start button and it is all good. Just like a modern motor on cold start.

But like you you have said Rusty I will like to take a look as well. The new kits have cromemolly rings. They are old kits and the pistons and rings are set in the sleeves. The failure could be do to a loose of spring tension in the rings from being compressed for so long. That is the only thing I can come up with,.

Are you sure the new kits have "chrome-molly" rings ? If that is so then that could be the problem right there. These engines where not designed to use chrome-molly rings. They are too hard to seat properly without the proper hone pattern on the bores, and the correct break-in procedure. It's been a few years since I seated a set of chrome-molly rings, but if I remember right you must work that engine "hard" during the break-in or the rings will never seat properly and will actually make the bores smooth as glass causing all kinds of blow-by and low compression. Now chrome-molly is great for high compression race engines and will last a long time once broken-in, but in our application I think the good old cast rings are a better fit. I need to research this some more.

 

[Wildchild467]

I thought I didn't a decent job at putting it under a load. I tried to put it under a load the best I could. Ill have to do a leak-down test someday and see where my numbers are after this 3rd overhaul. I'm about ready to throw in the towel and put a 4-71 under the hood. But if i rebuilt one of those, I might still have blow-by if I can't put it under a load. I'm rebuilding an 4.3 Chevy now for my boat and I am hoping that turns out good. I need a redeemer for all the confidence hits i took from rebuilding the LDT. If this boat engine turns out, maybe I'll feel better. Knowing my luck, it will throw a rod out the bottom of the hull. Ill be going down with the ship just like in the cartoons if it does! Bubbles and all! Haha!

 

[frank8003]

I only get to 1300 up a big hill. I don't let get that high. I run pump Diesel.

The "pump diesel" that one buys now has little reference to the
fuel that came in the truck way back when built.
Since you can't hurt it now just put a gallon of naphtha in the
tank of that "new" diesel fuel and a gallon of new motor oil,.

 

[o1951]

I only get to 1300 up a big hill. I don't let get that high. I run pump Diesel.
View attachment 627740

 

[Another Ahab]

I only get to 1300 up a big hill. I don't let get that high. I run pump Diesel.
View attachment 627740

 

[rustystud]

Well I did a little research last night about these rings. First off the hone pattern needs to be more aggressive and not as "smooth" a finish as you normally would have. Second, you need to put that engine under some serious load right after getting oil pressure ! The ring manufacture "Hastings" actually recommends that you Dyno the engine it to break it in. If that is not possible, then it needs to be driven with a 75% load on some good hills in the highest gear possible without lugging the engine. You need to very the RPM will doing this too. You need to do this for 100 to 500 miles, then change the engine oil. Then continue the break-in procedure till you reach 1000 miles. So basically drive it like you stole it !!!! Chrome rings can take up to 10,000 miles to totally break-in too.
Just a little side note. There is no such thing as a Chrome-moly ring. What there is, is a top ring with a chrome finish and a moly second ring. The third ring is of course the oil ring and it is usually cast-iron. The companies call this set "Chrome-moly" rings. The top chromed ring can take extreme heat and pressure and lasts a good long time, but it wears the bore faster then the stock cast-iron ring. Which in our engines is not a concern since you replace the "jugs" when you rebuild the engine anyway. So your not damaging the block.

 

[frank8003]

The "pump diesel" that one buys now has little reference to the
fuel that came in the truck way back when built.
Since you can't hurt it now just put a gallon of naphtha in the
tank of that "new" diesel fuel and a gallon of new motor oil,.

Can't hurt. My fuel tank is in continual recirculation mode and this suggestion is just one of many but is my version of Seafoam.

 

[rustystud]

Can't hurt. My fuel tank is in continual recirculation mode and this suggestion is just one of many but is my version of Seafoam.

Frank, did you just respond to your own post ?

 

[texas30cal]

Wildchild, I'm not sure if you are open to the idea, or if it's listed here but fuzzytoaster has a good running lds from a 5 ton that he just parted out.

 

[ShawnIfert]

I looked at the rings and that is what they appeared to be. You usually have that when you run in a two ring configuration. The cross hatch pater was about 220 grit or higher and that is the parameters for a Crome and moly ring set. I did not use rms meter. I have used on for years inspecting bores and just by eye I would say I am in the ball park.

 

[rustystud]

Frank, did you just respond to your own post ?

I wasn't trying to get on your case Frank. I'm just concerned. All the men in my family have died from strokes and slurring speech and writing differently then before are all signs. As is memory lose. A check-up with a doctor is a good thing every now and then. My one uncle had over 100 mini-strokes before the big one took him out. Thankfully my father had a massive one and never woke up. He died three days later.

 

[rustystud]

I looked at the rings and that is what they appeared to be. You usually have that when you run in a two ring configuration. The cross hatch pater was about 220 grit or higher and that is the parameters for a Crome and moly ring set. I did not use rms meter. I have used on for years inspecting bores and just by eye I would say I am in the ball park.

You usually have what ? Chrome-moly rings ? I've never heard of that. Usually, (as in the normal) rings are cast iron unless specified by the customer since they are so expensive. Of course they are making rings form some crazy stuff nowadays and chrome-moly is a "has been" on the race circuit.

 

[Wildchild467]

I probably need to collect some data and see what my engine is actually doing. Do a compression and leakdown test to get those numbers. I might be able to use a friends dyno but he is very busy and not sure when I could get on that. In the military rebuild manual, they dyno every engine after rebuild from the depot. I would just go that route if i were to do it all over again. Where does fuzzytoaster live? I really don't feel like working on the truck any more but I might force myself to just because I don't know when to quit. I would need a cylinder head wrench to do the job again. anybody have a mil spec one they want to sell? I should buy one if i keep pulling the heads off so many times.

 

[74M35A2]

82 pages and still blowing smoke from the straw. I told you that you can use the dyno any weekday or weekend night. It is 2wd rollers, so you need to disable one drive axle and remove the outer wheels of the one on the rollers. Can load up to 500hp intermittent, 350hp continuous, for as long as you want. Simulate uphill, downhill, variable frontal wind speed constant speed or match to roller speed, temp from -40C to +50C, humidity from 5%-99%, solar radiation up to 1400W/m^2, and free tow service to it.

 

[Wildchild467]

82 pages and still blowing smoke from the straw. I told you that you can use the dyno any weekday or weekend night. It is 2wd rollers, so you need to disable one drive axle and remove the outer wheels of the one on the rollers. Can load up to 500hp intermittent, 350hp continuous, for as long as you want. Simulate uphill, downhill, variable frontal wind speed constant speed or match to roller speed, temp from -40C to +50C, humidity from 5%-99%, solar radiation up to 1400W/m^2, and free tow service to it.

Thanks Bud. I think I posted this before, but here is the "Long Break-in" procedure for an LDT that has had new bearings (does not apply to me), new pistons (does not apply to me), Pistons rings (applies to me) and new sleeves (does not apply but my sleeves will be honed with a 240 grit ball hone). This is all the military says should be done. So do we follow this procedure to the word or do we go longer? or do the procedure 3 or 4 times? Run it until we run it out of fuel. Make it grunt.

 

[74M35A2]

When the procedure was authored, were the rings chrome plated? Are non-plated cast iron rings available for the engine today? I would study more deeply on break in procedure for chrome plated rings on various engines before doing anything.

Really, what I would do, if you are determined to keep the engine, is call Hastings and ask them to quote you a set of standard cast iron (non-chrome) rings for those pistons. You could send them an example piston and ring set to use as a dimensional template. It would probably not be as expensive as you think. What about the agricultural tractor application? Could those be available in conventional cast iron, fit and work? Ask Hastings how to break in chrome rings against a cast iron bore if only chrome is available.

Yes, there is no such thing as a chrome-moly ring. Above is correct.

Dyno display shows absorbed wheel hp. Use 10% driveline loss for manual trans once warmed up. Note: Spec procedure indicates to set and achieve 2600rpm for 15 minutes. If you are not willing to do this, then I don't want to spend the time to do the setup.

I can run anything out of fuel. Practice makes perfect.

 

[74M35A2]

.

 

[Wildchild467]

When the procedure was authored, were the rings chrome plated? Are non-plated cast iron rings available for the engine today? I would study more deeply on break in procedure for chrome plated rings on various engines before doing anything.

Really, what I would do, if you are determined to keep the engine, is call Hastings and ask them to quote you a set of standard cast iron (non-chrome) rings for those pistons. You could send them an example piston and ring set to use as a dimensional template. It would probably not be as expensive as you think. What about the agricultural tractor application? Could those be available in conventional cast iron, fit and work? Ask Hastings how to break in chrome rings against a cast iron bore if only chrome is available.

Yes, there is no such thing as a chrome-moly ring. Above is correct.

Dyno display shows absorbed wheel hp. Use 10% driveline loss for manual trans once warmed up. Note: Spec procedure indicates to set and achieve 2600rpm for 15 minutes. If you are not willing to do this, then I don't want to spend the time to do the setup.

I can run anything out of fuel. Practice makes perfect.

I'll look into more about the piston rings. As far as I know, they only had one flavor of piston rings. I just ordered the tractor service manual so we will see if that has any additional information in it. I believe the tractor pistons were different from the multifuel pistons. As far as piston ring differences between the two, I do not know. Maybe the tractor manual will go over what the rings are made out of for the tractor application and what the break in procedure is. Also I would like to see how many piston rings they have. If they have the same number, I would like to see what they say the ring clocking should be. the military manaul says 90 degrees apart. So does that mean the top ring, is at 12:00, second ring at 6:00, third ring at 3:00 and the 4th ring at 9:00... OR.... the top ring at 12:00, the second at 3:00, the third one at 6:00 and the 4th one at 9:00... ETC. I just want to follow everything exactly (like I have been doing for the past 3 overhauls).

Sounds good with the dyno.

If anybody has any NOS piston rings, pistons, sleeves, rod bearings, head gaskets, cylinder head wrench, etc, they want to donate to the cause I would welcome the support!