140,000 mile LS1 engine leak down results
If it's not sealing (bent valve, hole in piston, etc.), you will not build compression, = 0
03-04-2010, 12:58 PM
#45
maybe it is different depending on which tool you use. the one i had used 2 guages. you plug in a air compressor and adjust the regulator until the guage on the right reads zero (zero air escaping) once you plug it into the cylinder, it will show you how much air is being let loose.
if a valve was open it would jump over to 100% leaking right away. once both valves shut (turn the crank) it will start moving back towards 0% blowby (impossible)
have i confused anyone yet? lol. im not the best at explaining stuff.
03-04-2010, 01:05 PM
#46
TECH Junkie
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lol, I was just saying dlt had a compression check done, with values of 0-75 psi. I think you missread it as a leakdown of 75 %. im done here ha.
Do you have any vids of the truck on spray?
Do you have any vids of the truck on spray?
03-05-2010, 07:15 AM
#48
0% leak down would mean that your cylinder is completely sealed and will not let any air escape to your heads or crankcase. your rings will always let some air escape to the crankcase if your valves are shut, therefore 0% is impossible...
maybe it is different depending on which tool you use. the one i had used 2 guages. you plug in a air compressor and adjust the regulator until the guage on the right reads zero (zero air escaping) once you plug it into the cylinder, it will show you how much air is being let loose.
if a valve was open it would jump over to 100% leaking right away. once both valves shut (turn the crank) it will start moving back towards 0% blowby (impossible)
have i confused anyone yet? lol. im not the best at explaining stuff.
maybe it is different depending on which tool you use. the one i had used 2 guages. you plug in a air compressor and adjust the regulator until the guage on the right reads zero (zero air escaping) once you plug it into the cylinder, it will show you how much air is being let loose.
if a valve was open it would jump over to 100% leaking right away. once both valves shut (turn the crank) it will start moving back towards 0% blowby (impossible)
have i confused anyone yet? lol. im not the best at explaining stuff.
03-05-2010, 07:41 AM
#49
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just my opinion here and it may not apply to your truck.
With a spark plug like that i would say you have a little detonation. When you make a pass with detonation, it rattles the rings inside the bore. And will suck some oil into the chamber, and breed more detonation. IE burnt plugs, etc etc . It will also lose ring seal against the cylinder wall. If the cam timing is overlapping at the time you are detonating , it is possible to pressure the crankcase and then on the intake stroke, pull oil from the crankcase. And the cam timing events can cause you to suck oil up into the manifold.
In order to burn a plug, and use that much oil i would say you have a good sized problem. Fix the tune up, it will probably run faster and cure some of your problem.
You could also have a blown head gasket. It could be blown from the cylinder to the crankcase and not to water. In that case, you wouldnt really see it on a leakdown if it were a small breach. The only time it would actually leak past is when you are making lots and lots of cylinder pressure. (nitrous or high rpm)......
Things to think about. First things first, i would definately get a little timing out of that thing before you do any more damage. Just my .2 cents
With a spark plug like that i would say you have a little detonation. When you make a pass with detonation, it rattles the rings inside the bore. And will suck some oil into the chamber, and breed more detonation. IE burnt plugs, etc etc . It will also lose ring seal against the cylinder wall. If the cam timing is overlapping at the time you are detonating , it is possible to pressure the crankcase and then on the intake stroke, pull oil from the crankcase. And the cam timing events can cause you to suck oil up into the manifold.
In order to burn a plug, and use that much oil i would say you have a good sized problem. Fix the tune up, it will probably run faster and cure some of your problem.
You could also have a blown head gasket. It could be blown from the cylinder to the crankcase and not to water. In that case, you wouldnt really see it on a leakdown if it were a small breach. The only time it would actually leak past is when you are making lots and lots of cylinder pressure. (nitrous or high rpm)......
Things to think about. First things first, i would definately get a little timing out of that thing before you do any more damage. Just my .2 cents
03-05-2010, 08:35 AM
#50
ill definatley get the tune checked. most likely i will just put race fuel to it on the nitrous and leave the tune alone. all of the other plugs looked perfect.
as for the oil consumption, this has been going on for years...since before i ever installed the nitrous. ive had the heads off twice and put different gaskets in it every time and still drank some oil. last time i had the fast 90 split open it was soaked with oil. im pretty sure its the throttle body sucking it all up and the motor is just spitting it out.
as for the oil consumption, this has been going on for years...since before i ever installed the nitrous. ive had the heads off twice and put different gaskets in it every time and still drank some oil. last time i had the fast 90 split open it was soaked with oil. im pretty sure its the throttle body sucking it all up and the motor is just spitting it out.
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