95 240 SX Compression???
95 240 SX Compression???
Any one know the compression specs for a 95 240SX?? Anyone know the best way to perform the compression test? If you just know the specs or how to perform the test, either will be appreciated. Thanks.
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drunkmonkalan
- Posts: 88
- Joined: Thu Sep 25, 2003 8:10 pm
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Structure240sx
- Posts: 5615
- Joined: Sun Oct 06, 2002 5:04 pm
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Nismo_Freak
- Posts: 10314
- Joined: Wed Jul 24, 2002 10:42 pm
- Car: 89 Nissan 240SX
What's the psi for the KA24E?
I having some smoke problem during WOT at times. I suspect my piston rings and did a compression test. Unfortunately, my results are probably inconclusive.
Piston 1: 167Piston 2: 171Piston 3: 169Piston 4: 168
They seemed to be within specs of each other. Then again, my motor may have valve seal problems.
I having some smoke problem during WOT at times. I suspect my piston rings and did a compression test. Unfortunately, my results are probably inconclusive.
Piston 1: 167Piston 2: 171Piston 3: 169Piston 4: 168
They seemed to be within specs of each other. Then again, my motor may have valve seal problems.
142 is pretty low. To get that low, I'm expecting a CR of 8.5:1.
My car has a second motor in it, and I'm the 3rd or 4th owner of the car. It's very hard to track down the history. The first motor (previous owner gave it to me for free - approx 140K mileage top) spun a rod bearing and blew a head gasket, and I took the motor apart and sold parts off it (not the broken ones).
The second motor was in the car when I bought the 240. He couldn't or wouldn't give me the mileage info on the second motor. From the looks on the transmission fluid after replacing w/ new fluids (most people don't change it), I have to guess the low 80K to a whopping 125K mileage. Besides, I don't trust the mileage on the tach . . . along the way, I think someone rolled the odo backwards a bit. The trip meter is busted.
Problems: 1) the motor is eating a qt of oil per 4-6 weeks.2) when I get off the gas hard, the exhaust blows a slight gray smoke. Now, I'm worrying about a possible slight head gasket problem, besides valve seal at WOT.
My methodology for the compression test:1) took off the plug wires to prevent accidental firing2) mash the throttle 100%3) crank 4-6 times until it doesn't peak anymore.
My car has a second motor in it, and I'm the 3rd or 4th owner of the car. It's very hard to track down the history. The first motor (previous owner gave it to me for free - approx 140K mileage top) spun a rod bearing and blew a head gasket, and I took the motor apart and sold parts off it (not the broken ones).
The second motor was in the car when I bought the 240. He couldn't or wouldn't give me the mileage info on the second motor. From the looks on the transmission fluid after replacing w/ new fluids (most people don't change it), I have to guess the low 80K to a whopping 125K mileage. Besides, I don't trust the mileage on the tach . . . along the way, I think someone rolled the odo backwards a bit. The trip meter is busted.
Problems: 1) the motor is eating a qt of oil per 4-6 weeks.2) when I get off the gas hard, the exhaust blows a slight gray smoke. Now, I'm worrying about a possible slight head gasket problem, besides valve seal at WOT.
My methodology for the compression test:1) took off the plug wires to prevent accidental firing2) mash the throttle 100%3) crank 4-6 times until it doesn't peak anymore.
It eats some oil and if i romp on it before its good and warm it'll smoke some. Lifter noise too! It runs strong though.=============================I have the same problem too, except the lifter problem. The injectors firing off is louder than the lifters, unless I hear it in the cabin.
The plugs condition should tell you if you are consuming oil. Oily plugs. ====================That's the first thing I checked before the compression test. A couple months ago, I have put new plugs, and the results look normal w/ carbon, not oily or stalactites of carbon buildup or residue.
Leaks, I may have a few leaks, but I can't really see around too may vacuum and emission lines. It's not dripping all over the block or onto the driveway. In the past, I had an Olds Ciera that had both bad cyl head and valve cover gaskets. It leaked all over the place, but it didn't consume this much oil or smoked at all.
No real emission laws in FL.
Wow, a rebuild will burn a hole in my wallet. Then again, I do have an extra cyl head, just need some time and effort to clean it up a bit . . . if the valves seals are bad on the running motor.
The plugs condition should tell you if you are consuming oil. Oily plugs. ====================That's the first thing I checked before the compression test. A couple months ago, I have put new plugs, and the results look normal w/ carbon, not oily or stalactites of carbon buildup or residue.
Leaks, I may have a few leaks, but I can't really see around too may vacuum and emission lines. It's not dripping all over the block or onto the driveway. In the past, I had an Olds Ciera that had both bad cyl head and valve cover gaskets. It leaked all over the place, but it didn't consume this much oil or smoked at all.
No real emission laws in FL.
Wow, a rebuild will burn a hole in my wallet. Then again, I do have an extra cyl head, just need some time and effort to clean it up a bit . . . if the valves seals are bad on the running motor.
hey quick question about compression testing that I never really understood:
if the compression in our engines is 9.5:1, that means that the max pressure inside the cyl is 9.5 times atmospheric pressure (or roughly 9.? bar), right?
but that doesnt really make sense because atmospheric pressure is about 14.5psi, so 9.5 times that should be closer to 138psi. Where is the extra compression coming from if we're testing our engines at ~180psi? I would imagine that the real pressure (as tested) would actually be LOWER than the calculated figure just based on valves opening and various physical problems (minimal leaking through rings, headgasket, etc.... Im just saying that the cyl isnt perfectly airtight...). Whats goin on here then?
if the compression in our engines is 9.5:1, that means that the max pressure inside the cyl is 9.5 times atmospheric pressure (or roughly 9.? bar), right?
but that doesnt really make sense because atmospheric pressure is about 14.5psi, so 9.5 times that should be closer to 138psi. Where is the extra compression coming from if we're testing our engines at ~180psi? I would imagine that the real pressure (as tested) would actually be LOWER than the calculated figure just based on valves opening and various physical problems (minimal leaking through rings, headgasket, etc.... Im just saying that the cyl isnt perfectly airtight...). Whats goin on here then?