Just bought a k24a2 from a jdm dealer promoting 50k miles or less and wanted to do a compression test. Dry test numbers were 123 120 115 120. and wet test with cap full of oil in each cylinder head 138 140 135 125. I have no clue how long this thing has been sitting or really much about these engines trying to figure out if these numbers are good or bad.
K24a2 compression numbers HELP!
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Sounds good I’ll try that, I’m going back today after work and see how it goes
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Return it if possible, I'm sure it comes with some type of return policy. Flamie is mostly right, the only thing I would add is that the compression numbers should be within a certain range of each other. 20% I believe. Example. 145, 150, 145, 150. etc. As a general rule a compression of 135 PSI or better is excellent. Similarly, a compression of 85 PSI or lower is extremely bad. The most desirable situation is that all cylinders, give the same or close to the same reading.
There’s a 30 day warranty and they have 2 more if this one doesn’t work out, thank you I appreciate it I’ll be testing again today
I would think it'd be higher than 130's. My integra with almost 200k miles was around that.
Just make sure you're tightening down the tester as much as possible to avoid any potential compression loss. It shouldn't be that noticeable, but 130's is concerning in my opinion. They're all within 10% so at least it's consistent.
A little more reading shows that 135 is the minimum pressure (according to the service manual)
Just make sure you're tightening down the tester as much as possible to avoid any potential compression loss. It shouldn't be that noticeable, but 130's is concerning in my opinion. They're all within 10% so at least it's consistent.
A little more reading shows that 135 is the minimum pressure (according to the service manual)
Agreed. I think the manual is stating the bare minimum, not the optimal
yeah I am not sure what most people's TSX's blow, but I did mine like a half a year ago with about 105k miles on it and it was 220ish all holes. I am sure it still is gonna be like over 200 now still. feels just as fast and sounds just as hot. if you maintain your oil and check stuff like timing chain stretch and valve lash normally and be on top of things it should last forever. I change my oil every 3k ish miles. I use redline 5w30 and a bosch filter and never had an issue. My car does burn oil, but it has 113k miles I think that is kinda normal, especially cause I race it and it's constantly at 8k rpm lmao
Yeah, this is right. cause if one is down alot more than others it's not engine wear issue it's bent valves or some sort of serious issue, if it's all in the same number range within like 10 or 5 numbers it should be pretty solid, obviously tho if it's not all worn out in general. Like that engine sounds kinda done. but it's not a valve or serious problem, just worn rings probably.
So I called the place I got the motor from and basically the guy said when the motors are installed on the cars and actually run the compression numbers will be better/ higher then when I’m compression testing the motor after who knows how long it’s been sitting for from being shipped from Japan. He said I can get a different motor but it will probably be the same situation but what’s good is that the numbers are close even if they’re low. Should I try a different one ? Keep the one I have ? This motor is for my s13 and probably won’t be going in for a year and will be boosted, any suggestions on what I should do ?
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Me personally, I would return and get another one. I'm not buying what he's saying. The one you have could have been driven harder low on oil compared to another one you pick out.
Yeah.. I don't know what it has to do with being in the car. Like the only thing I can think of is sometimes motors have lower compression when not oiled cause they have no seal from the oil. I have this happen when I buils my RC nitro motors. But that is the real compression. Also if your spinning over the motor and it has oil in it then the pump should be going and it should oil up. If your doing it dry, try adding oil and see what it does
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think the manual is stating the bare minimum, not the optimal
As mentioned 7 months ago.
He's probably right. Compression tests are supposed to be done with the engine hot, after being run. The parts expand to their normal operating dimensions, and clearances tighten up when hot (by design).
Repeat the compression check 2-3 times to try to get an average and dial in your technique for consistently.
Also the cylinder wall-to-ring seal is enhanced by oil on the walls. Not sure how much oil would get delivered spinning the motor with the starter... oil is delivered to the walls by splashing or squirters (not sure how this engine does it). Either way, you need some rpm to splash the oil hard enough or build pressure so the squirters can reach... I'm guessing this engine has squirters, also guessing the starter can't run the oil pump fast enough to deliver the needed pressure. So having run the engine recently is probably important for both clearances and wall lubrication. The walls would be bone dry on an engine that's been sitting (or came out of a crate).
Wet test really only needs to be done in the case of large differences between cylinders, to determine if the problem is valves or rings, it provides extra oil on top of the rings which will help seal a bad set of rings. If you had low across the board dry numbers, you could do a wet test to get a feel for piston/ring/liner wear... just to see how big of a difference.
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