Ran a compression test on my 98 LS1, tell me what you tnk.
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Ran a compression test on my 98 LS1, tell me what you tnk.
Alright, here are the numbers, Im thinking I have a burnt valve or bent push rod or something maybe bent valve, it pops and backfires, alot of valvetrane noise on the passenger side. Not sure what compression should be but here it is.
#1 210
#3 220
#5 200
#7 210
#2 210
#4 180
#6 180
#8 (didnt do it, too hard, tried for an hour) guessing its around 200)
Let me know what anyone thinks of this. Help is appreciated.
#1 210
#3 220
#5 200
#7 210
#2 210
#4 180
#6 180
#8 (didnt do it, too hard, tried for an hour) guessing its around 200)
Let me know what anyone thinks of this. Help is appreciated.
#2
The minimum compression in any one cylinder should not be less than 70 percent of the highest cylinder. No cylinder should read less than 690 kPa (100 psi). For example, if the highest pressure in any one cylinder is 1035 kPa (150 psi), the lowest allowable pressure for any other cylinder would be 725 kPa (105 psi). (1035 x 70% = 725) (150 x 70% = 105).
Normal -- Compression builds up quickly and evenly to the specified compression for each cylinder.
Piston Rings Leaking -- Compression is low on the first stroke. Compression then builds up with the following strokes but does not reach normal. Compression improves considerably when you add oil.
Valves Leaking -- Compression is low on the first stroke. Compression usually does not build up on the following strokes. Compression does not improve much when you add oil.
If two adjacent cylinders have lower than normal compression and injecting oil into the cylinders does not increase the compression, the cause may be a head gasket leaking between the cylinders
and "guessing" at number 8 is not going to help you, try going from under the car.
Normal -- Compression builds up quickly and evenly to the specified compression for each cylinder.
Piston Rings Leaking -- Compression is low on the first stroke. Compression then builds up with the following strokes but does not reach normal. Compression improves considerably when you add oil.
Valves Leaking -- Compression is low on the first stroke. Compression usually does not build up on the following strokes. Compression does not improve much when you add oil.
If two adjacent cylinders have lower than normal compression and injecting oil into the cylinders does not increase the compression, the cause may be a head gasket leaking between the cylinders
and "guessing" at number 8 is not going to help you, try going from under the car.
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The minimum compression in any one cylinder should not be less than 70 percent of the highest cylinder. No cylinder should read less than 690 kPa (100 psi). For example, if the highest pressure in any one cylinder is 1035 kPa (150 psi), the lowest allowable pressure for any other cylinder would be 725 kPa (105 psi). (1035 x 70% = 725) (150 x 70% = 105).
Normal -- Compression builds up quickly and evenly to the specified compression for each cylinder.
Piston Rings Leaking -- Compression is low on the first stroke. Compression then builds up with the following strokes but does not reach normal. Compression improves considerably when you add oil.
Valves Leaking -- Compression is low on the first stroke. Compression usually does not build up on the following strokes. Compression does not improve much when you add oil.
If two adjacent cylinders have lower than normal compression and injecting oil into the cylinders does not increase the compression, the cause may be a head gasket leaking between the cylinders
and "guessing" at number 8 is not going to help you, try going from under the car.
Normal -- Compression builds up quickly and evenly to the specified compression for each cylinder.
Piston Rings Leaking -- Compression is low on the first stroke. Compression then builds up with the following strokes but does not reach normal. Compression improves considerably when you add oil.
Valves Leaking -- Compression is low on the first stroke. Compression usually does not build up on the following strokes. Compression does not improve much when you add oil.
If two adjacent cylinders have lower than normal compression and injecting oil into the cylinders does not increase the compression, the cause may be a head gasket leaking between the cylinders
and "guessing" at number 8 is not going to help you, try going from under the car.
Last edited by Mike96z; 06-28-2008 at 11:51 AM.
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Ok first of all dont guess on #8, you have no idea.
I had all of them at 180 and one at 60... and the car ran fine
Second they are ok, 180 is more common than 220 from what I've seen of people posting them.
180 to 220 is a bit of a variance, but again 180 seems to be the norm. Maybe you got that variance from technique?
You did pull the fuel pump fuse right?
I had all of them at 180 and one at 60... and the car ran fine
Second they are ok, 180 is more common than 220 from what I've seen of people posting them.
180 to 220 is a bit of a variance, but again 180 seems to be the norm. Maybe you got that variance from technique?
You did pull the fuel pump fuse right?
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Ok first of all dont guess on #8, you have no idea.
I had all of them at 180 and one at 60... and the car ran fine
Second they are ok, 180 is more common than 220 from what I've seen of people posting them.
180 to 220 is a bit of a variance, but again 180 seems to be the norm. Maybe you got that variance from technique?
You did pull the fuel pump fuse right?
I had all of them at 180 and one at 60... and the car ran fine
Second they are ok, 180 is more common than 220 from what I've seen of people posting them.
180 to 220 is a bit of a variance, but again 180 seems to be the norm. Maybe you got that variance from technique?
You did pull the fuel pump fuse right?
pulled the fuel fuse for injectors in all, there is no way that compression tester is going into number 8, when I pull the headers and im about to pull the heads, ill slip it in there, im pretty sure its gonna give a normal reading. Maybe theres more room in an LSx car but in a swapped car, well atleast mine, there is no room, I have the hooker super comp LT's and makes it nearly impossible to get that hose on there with the headers installed. Im going to pull the heads no matter what, wanna go to a better casting. Thanks for letting me know that 180+ is norm, thats one thing I needed to know. The plug in #8 looked good too. Technique was, pull the plug, insert the hose, had someone watching the guage and seeing how it came up on the guage, then I turned it over until it met max pressure.
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pull all the plugs
unplug the coils
push the gas WOT, crank it, do 4 compression revs (WOT cranking= no IPW, no need to do anything with the fuel pump)
do it on a cold motor, or a warm motor fast. RnR the plugs on a car with airtubes and AC your going to take to long if its still warm.
unplug the coils
push the gas WOT, crank it, do 4 compression revs (WOT cranking= no IPW, no need to do anything with the fuel pump)
do it on a cold motor, or a warm motor fast. RnR the plugs on a car with airtubes and AC your going to take to long if its still warm.
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pull all the plugs
unplug the coils
push the gas WOT, crank it, do 4 compression revs (WOT cranking= no IPW, no need to do anything with the fuel pump)
do it on a cold motor, or a warm motor fast. RnR the plugs on a car with airtubes and AC your going to take to long if its still warm.
unplug the coils
push the gas WOT, crank it, do 4 compression revs (WOT cranking= no IPW, no need to do anything with the fuel pump)
do it on a cold motor, or a warm motor fast. RnR the plugs on a car with airtubes and AC your going to take to long if its still warm.
#12
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without the plugs you can hear the singal compresion stroke easly. 4 is just a good number. if you have weird numbers or doing a leak down, adding oil ect. you can do more, just dont over heat the starter.
un-pluging the coils:, I forgot to say just the 1 large white conectors to the hanress along the fuel rails, works great.
un-pluging the coils:, I forgot to say just the 1 large white conectors to the hanress along the fuel rails, works great.
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Now delete your account and leave thanks. People like you are worthless. This forum is about learning and helping nothing to do with insulting. Want to do that hit youtube.
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Classic....Did you realize the post is from 2009?? The guy hasn't even browsed or posted the site since 2009