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He stated earlier that he did not measure the sleeve heights. When he said he heard a pop sound while torquing down the heads, that got me thinking.
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Piston Rings Worn Out, Time for a Rebuild
- Thread starter Wildchild467
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ShawnIfert
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Oil pressure is higher that coolant pressure. You would see oil in the coolant. You need to do an exhaust gas test on your cooling system. I have seen funny things from a cracked head. Sometimes it pressurizes the cooling system and coolant goes everywhere or when the engine is cold it leaks coolant into the engine but when it warms the leak seals up. The Ltd/Lds heads do have an issue with cracking between the valves. How much oil are you gaining?? I had seen you pic of the blow by. It reminded me of a Cummings 250 that had water put in instead of coolant and one of the freeze plugs under the valve cover had a rust hole and started to leak coolant into the engine and steam was come out of the breather like your engine.
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So I'm in the process of rebuilding my LDT, converting it to an LDS. I have a rebuilt LDS injector pump, ordered the LDS intake rockers. The LDS pistons and sleeves came the other day. I pull a piston out of one sleeve today, measured everything, I did notice that the sleeves haven't been honed. What grit hone and hone type is recommended. I did not find this in the TM.
ShawnIfert
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The sleeves I have received had a very light hone but that is not unusual. The liners were done by a machine, not by hand that makes a big difference. If the rings are moly it would be very smooth.
Most OEMs and ring manufacturers specify a surface finish of 15 to 25 RA for moly faced rings, which can be achieved by finish honing with #280 grit stones. Cast iron and chrome rings can tolerate a somewhat rougher surface finish (20 to 35 RA), so coarser #220 grit stones can be used to produce this type of finish.
Keep in mind that a 7 RA is a mirror finish.
- 3,248
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I know that rocker arm differences for the intake valves have been mentioned before. TM9-2815-210-34-2-1 tabulates the LD/LDS/LDT engines (table 1.3) and just above the table speaks to the rocker arms. It states that the intake rocker arms for the LDS-465-2 are different in that they have an oil hole and can be used as a replacement on all other LDS engines. It also states that the assembled rocker arms etc. are interchangeable between all listed engines except the LDS-465-2.
It seems to me, from this, that a LDS-465-1A or 1C has the exact same rocker arms as an LDT. I will shoot a side-by-side pic once I get my other engine opened up.
gimpyrobb
dumpsterlandingfromorbit!
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Its been measured, there is more throw(longer rocker arm) on an LDS rocker.
- 330
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- greenville sc
I will measure the ratio of the LDS intake rocker arm when I received them. I have measured the ratio of the LDT, it's
1:1.65
1:1.65
gimpyrobb
dumpsterlandingfromorbit!
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Its been posted, I think in the LDT/LDS difference thread.
- 330
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Back to the new LDS piston sleeves, I did a closer inspection.
In the sunlight, you can see very fine hone marks.
In the sunlight, you can see very fine hone marks.
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- 330
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I measured the OD and ID of the new LDS sleeves, besides the wear on my original sleeves, everything is the same. Measured the pistons, besides one less compression ring, it's the same. What is different on the new LDS piston is the volume of the piston chamber. I do not have a CC Barret anymore, but I used a 50cc syringe. I used water, and no top plate, so the results are estimates. The LDT piston has approximately a 50cc chamber in it, the LDS piston has approximately a 60cc chamber in it. This will lower the compression ratio by around 3/4 to 1 point.
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I believe the hone I used was 220 Grit. It was the most universal grit size to use depending on what your rings are made out of.
74M35A2
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Wildflower wanted me to post this video he shot yesterday with his calculator on its side. 58 pages of blow-by! Now going the path of installing another used LDT engine.
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ShawnIfert
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That is because when you introduce more fluid/air that changes the compression ratio!! The combustion bowl is designed to handle a greater fuel/air volume. The consumption of fuel goes from 10 mph to like 5 mph. You would hydro lock the engine without the extra capacity.
ShawnIfert
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sorry that would lower the ratio to like 20:1
o1951
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Did yu try loading it up with a proper break in oil, like we suggested? Ya got little to loose now. Give it a shot before yu pull it and put in that big Cummins of your dreams.
rustystud
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I was wondering what you where talking about
. There where two compression ratios used in the multifuel engines. The 22:1 and the 20:1 . Evidently these pistons are for the 20:1 ratio engine.
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- greenville sc
The LDS intake rocker arms came today.
I remeasured the LDT rocker, then with the same setup, I measured the LDS. Their is a big difference.
LDT 1:1.5
LDS 1:1.9
some of my measuring instruments are missing, so I used precision feeler gauges.
I sure I'm off a little, but their is still a big difference in the valve lift from the LDS rocker and the LDT rocker.
If anyone has the measuring instruments, feel free to post your results.
I remeasured the LDT rocker, then with the same setup, I measured the LDS. Their is a big difference.
LDT 1:1.5
LDS 1:1.9
some of my measuring instruments are missing, so I used precision feeler gauges.
I sure I'm off a little, but their is still a big difference in the valve lift from the LDS rocker and the LDT rocker.
If anyone has the measuring instruments, feel free to post your results.
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So, in practical terms, what does the difference mean? The longer LDS arm will push the valve stem farther (open the valve more), with the push rod travel being the same? The cross section of the air passages does not change - what is the significance, other than perhaps a little less obstruction? A little better/quicker fill?
- 330
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The rocker arm ratio opens the intake valve farther, along much more airflow. This also opens and closes the valve quicker. It has the same effect as putting a bigger cam in the engine.
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That video does not look like blow-by it looks like water vapor.
Are you chasing the wrong problem?
Are you chasing the wrong problem?