Diagnosing rebuilt engine - burning oil, lean, and low power up inclines
#31
05-03-2018, 09:07 AM
I'm not sure is our engines use a napier style compression ring?
They are also designed to scrape oil off the cylinder walls on the way down.
If they get put in upside down they do the opposite.
They are also every easy to chip during installation.
Piston Ring Tech - The Latest Developments In Cylinder Sealing - Hot Rod Network
They are also designed to scrape oil off the cylinder walls on the way down.
If they get put in upside down they do the opposite.
They are also every easy to chip during installation.
Piston Ring Tech - The Latest Developments In Cylinder Sealing - Hot Rod Network
#32
05-03-2018, 10:21 AM
Agreed... separate issues, but possibly related. I'm most optimistic about the exhaust being partially blocked. I think that could account for all of my issues, including running a tad hot (201-206 idle).
#33
05-03-2018, 10:39 AM
Recovery Vehicle
I'm not sure is our engines use a napier style compression ring?
They are also designed to scrape oil off the cylinder walls on the way down.
If they get put in upside down they do the opposite.
They are also every easy to chip during installation.
Piston Ring Tech - The Latest Developments In Cylinder Sealing - Hot Rod Network
They are also designed to scrape oil off the cylinder walls on the way down.
If they get put in upside down they do the opposite.
They are also every easy to chip during installation.
Piston Ring Tech - The Latest Developments In Cylinder Sealing - Hot Rod Network
So, they are directional.
Just as a datapoint, on my fresh rebuild I burned 1 quart of oil on my 1100 mile road trip this past weekend. I was expecting to burn 3. Was going to be happy with anything under 4.
#34
05-03-2018, 10:40 AM
#35
05-03-2018, 11:05 AM
Tell me about it! I know that I broke at least 2 of those compression rings during my installation. 1 was from spreading that ring tool too wide and the other was because I had to remove 1 ring and flip it upside down because I had installed it in the wrong direction.
So, they are directional.
Just as a datapoint, on my fresh rebuild I burned 1 quart of oil on my 1100 mile road trip this past weekend. I was expecting to burn 3. Was going to be happy with anything under 4.
So, they are directional.
Just as a datapoint, on my fresh rebuild I burned 1 quart of oil on my 1100 mile road trip this past weekend. I was expecting to burn 3. Was going to be happy with anything under 4.
Yes, they look original. A vacuum test and a back pressure test should reveal this, yes? However I've read that the blockage can be very partial, and those tests won't reveal an issue.
#36
05-03-2018, 11:13 AM
Recovery Vehicle
So I was expecting a higher oil burn rate, thinking that I was pushing tolerances on the second rebuild (and re-using the "old" B pistons).
Anyway, it all turned out ok. I did mic everything and it was all within book limits, so the factory does know what it is talking about!
#37
05-03-2018, 11:25 AM
From what I've read, burning 1 quart per 1,000 miles is completely normal and in spec.
Yes, they look original. A vacuum test and a back pressure test should reveal this, yes? However I've read that the blockage can be very partial, and those tests won't reveal an issue.
Yes, they look original. A vacuum test and a back pressure test should reveal this, yes? However I've read that the blockage can be very partial, and those tests won't reveal an issue.
The material inside the converter looks like a honeycomb or a grid.
Each individual section slowly gets stopped up by carbon. It doesn't nessacerily clog up evenly either, you can literally have half clear, and half completely blocked(I have gutted quite a few over the years, but never a LR).
It will cause engine temps to rise and power to go down.
An oil burner will cause this over time too, so you may very well have a domino effect problem.
Last edited by Sixpack577; 05-03-2018 at 11:27 AM.
#38
05-03-2018, 03:47 PM
Some more data for y'all
Pulled the brake booster to check vacuum
Vacuum pressure is a steady 13.5 hg at idle. (bad)
Quick rev drops to 0, shoots to 25, back to 13.5 (good)
Steady 2500 rpm, vacuum is 23, does not drop (good)
So it sounds like I either have a vacuum leak, incorrect valve timing or ignition timing. For the last two, I don't think those are configurable?? I aligned the timing chain as per manual, and that was it. Maybe the Kent H180 cam is mucking things up? But Turner swears by them. Idle is smooth, and don't notice any issues.
Pulled the brake booster to check vacuum
Vacuum pressure is a steady 13.5 hg at idle. (bad)
Quick rev drops to 0, shoots to 25, back to 13.5 (good)
Steady 2500 rpm, vacuum is 23, does not drop (good)
So it sounds like I either have a vacuum leak, incorrect valve timing or ignition timing. For the last two, I don't think those are configurable?? I aligned the timing chain as per manual, and that was it. Maybe the Kent H180 cam is mucking things up? But Turner swears by them. Idle is smooth, and don't notice any issues.
Last edited by Jeff Blake; 05-03-2018 at 03:52 PM.
#39
05-03-2018, 04:32 PM
#40
05-03-2018, 04:32 PM
Recovery Vehicle
Low vacuum pressure at idle suggests clogged exhaust.
"Low vacuum also can be an immediate clue to a plugged exhaust. To check further, run the engine at about 2500 rpm for about 15 seconds. If vacuum drops during this period and does not increase when you close the throttle, you're almost certainly looking at a restricted exhaust."
Also, have you considered an engine-off cranking vacuum test?
"Low vacuum also can be an immediate clue to a plugged exhaust. To check further, run the engine at about 2500 rpm for about 15 seconds. If vacuum drops during this period and does not increase when you close the throttle, you're almost certainly looking at a restricted exhaust."
Also, have you considered an engine-off cranking vacuum test?
You can get a quick basic appraisal of engine condition by connecting a vacuum gauge to the manifold and a tachometer to the ignition to check vacuum and rpm at cranking speed. Warm up the engine first, then shut it down and connect your test equipment. Close the throttle and disable the ignition, or use a remote starter so the engine won't start. Crank the engine for 10 to 15 seconds and observe the vacuum and tach readings.
Note that different engines produce different cranking vacuum readings. Some carmakers publish specifications; others don't. Again, experience will be your best guide. What you're looking for, most importantly, is steady vacuum and cranking speed.
If the cranking speed is steady (about 200 rpm) and vacuum also is steady (around 5 inches), the engine most likely is in good mechanical condition. If rpm and vacuum are uneven, the cylinders aren't pumping equally. The engine probably has leakage past the valves, rings or head gasket. If the vacuum reading is pretty steady but cranking speed is not, you're probably looking at a damaged flywheel ring gear or starter. If the cranking speed is normal or high but vacuum is low and slightly uneven, the engine probably has low compression or retarded valve timing. A jumped timing chain or belt is a common cause here.
The cranking vacuum test also can provide a quick test for PCV restrictions. Perform the test and note the average vacuum reading. Then pinch the hose to the PCV valve closed with your pliers and repeat the test. If the PCV system is clear, vacuum should increase. If it doesn't, check the PCV system closer for restrictions.
more: https://www.motor.com/magazine-summa...-vacuum-gauge/
Note that different engines produce different cranking vacuum readings. Some carmakers publish specifications; others don't. Again, experience will be your best guide. What you're looking for, most importantly, is steady vacuum and cranking speed.
If the cranking speed is steady (about 200 rpm) and vacuum also is steady (around 5 inches), the engine most likely is in good mechanical condition. If rpm and vacuum are uneven, the cylinders aren't pumping equally. The engine probably has leakage past the valves, rings or head gasket. If the vacuum reading is pretty steady but cranking speed is not, you're probably looking at a damaged flywheel ring gear or starter. If the cranking speed is normal or high but vacuum is low and slightly uneven, the engine probably has low compression or retarded valve timing. A jumped timing chain or belt is a common cause here.
The cranking vacuum test also can provide a quick test for PCV restrictions. Perform the test and note the average vacuum reading. Then pinch the hose to the PCV valve closed with your pliers and repeat the test. If the PCV system is clear, vacuum should increase. If it doesn't, check the PCV system closer for restrictions.
more: https://www.motor.com/magazine-summa...-vacuum-gauge/
Last edited by No Doubt; 05-03-2018 at 04:38 PM.
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