WhaTs A CoMpReSSioN TesT?
22-May-2003, 08:27 AM
#1
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WhaTs A CoMpReSSioN TesT?
Just wondering EXACTLY what a compression test is...Is the motor actually started? Or is this done while its off? Jugglez was telling me to look for a reading of 200psi 
22-May-2003, 08:32 AM
#2
Motor not started... plugs taken out of all cyls, compression gauge put into the spark plug hole, and the engine is cranked (using the starter or it can be done with a wrench manually) until the pressure stabilizes.... 200psi is an awesome motor, like brand new almost. If you get less than that, run a wet comp test, to see if it's the rings or the valve seals.
22-May-2003, 08:45 AM
#3
170 is still a healthy motor if all cylinders test about the same. Much lower readings indicate bad seals, rings, head gasket, cracked block, cracked head... a multitude of problems. B16A2 is a USDM engine... the JDM version should only have B16A stamped on, I'm pretty sure, but I'm not a JDM *****. 
94EG6HB and ryuujin, you guys wanna answer this one 
94EG6HB and ryuujin, you guys wanna answer this one
22-May-2003, 03:40 PM
#6
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cool...thats what i thought too...i only asked cause i emailed Osaka Motors asking if the JDM B16 has "B16A" on the block and they said thats not neccessarily true...its ok though...I dont think they will be one of my sources to get a motor...maybe theyre selling B16A2s and saying theyre JDM....or maybe not...anyways,
Can I do the compression test myself? What tools do I need?
Im guessing a wrench to turn the crank and some kind of special compression gauge?
Can I do the compression test myself? What tools do I need?
Im guessing a wrench to turn the crank and some kind of special compression gauge?
22-May-2003, 05:48 PM
#7
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if the motor is still in the car and running you just need the compression gauge. take out your spark plug wires. remove the spark plugs and screw the gauge in to the spark plug chamber. start the car and wait for 5 cranks and go take a look. repeat for all cylinders
different gauges will give different results. what you're looking for is consistency across all 4 cylinders.
200 psi across is good for a JDM second gen B16A.
different gauges will give different results. what you're looking for is consistency across all 4 cylinders.
200 psi across is good for a JDM second gen B16A.
22-May-2003, 05:49 PM
#8
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Location: Mississauga
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compression test? .... properly done like this;
- all plugs taken out
- throttle body held WIDE open (full throttle) to get the max amount of air into the clyinders
- disconnect all distributor connectors (1 or 2 connectors) this will disable the ignition and fuel injectors; you don't want injectors to fire fuel into the clyinders giving you false readings)*
- thread the tester into the cylinders and crank the engine until the reading stabilizes (about 4-6 cranks)
now, don't worry too much about the numbers. The main thing you care about is that the readings are consistent (within 20% of one another) If they're even then you'll know the motor's in decent condition. If one's low you know there's a problem; either rings or valve seals and do a wet test on the weak cylinder to determine the problem, and if possible a leak down test.
you don't want to see anything under 140psi as a minimum (generally) and depending on the compression of the engine it can vary from 160psi~200psi (remmeber *consistency* is the key)
ex. my motor;
#1cyl 220psi; #2 cyl 225psi; #3cyl 230psi; #4 225psi
- all plugs taken out
- throttle body held WIDE open (full throttle) to get the max amount of air into the clyinders
- disconnect all distributor connectors (1 or 2 connectors) this will disable the ignition and fuel injectors; you don't want injectors to fire fuel into the clyinders giving you false readings)*
- thread the tester into the cylinders and crank the engine until the reading stabilizes (about 4-6 cranks)
now, don't worry too much about the numbers. The main thing you care about is that the readings are consistent (within 20% of one another) If they're even then you'll know the motor's in decent condition. If one's low you know there's a problem; either rings or valve seals and do a wet test on the weak cylinder to determine the problem, and if possible a leak down test.
you don't want to see anything under 140psi as a minimum (generally) and depending on the compression of the engine it can vary from 160psi~200psi (remmeber *consistency* is the key)
ex. my motor;
#1cyl 220psi; #2 cyl 225psi; #3cyl 230psi; #4 225psi
22-May-2003, 05:53 PM
#9
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Originally posted by Solid Alibye
- throttle body held WIDE open (full throttle) to get the max amount of air into the clyinders
- disconnect all distributor connectors (1 or 2 connectors) this will disable the inition and fuel injectors; you don't want injectors to fire fuel into the clyinders giving you false readings)*
- throttle body held WIDE open (full throttle) to get the max amount of air into the clyinders
- disconnect all distributor connectors (1 or 2 connectors) this will disable the inition and fuel injectors; you don't want injectors to fire fuel into the clyinders giving you false readings)*
22-May-2003, 06:08 PM
#10
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thx alibye...how come your reading is so high? new engine?
- thread the tester into the cylinders and crank the engine until the reading stabilizes (about 4-6 cranks)
where can i get the tester?
crank the engine? if the motor is not in the car...do i just turn the crank a few times?
(Im asking all this cause Ill want to test the motor I buy)
- thread the tester into the cylinders and crank the engine until the reading stabilizes (about 4-6 cranks)
where can i get the tester?
crank the engine? if the motor is not in the car...do i just turn the crank a few times?
(Im asking all this cause Ill want to test the motor I buy)
22-May-2003, 06:11 PM
#11
I got my comp tester at Walmart for like $19 or something It doesn't matter, as long as you use the same tester on all the motors... so it's consistant. Duy... 
nice sig
Solid Alibye, thanks for typing all that up, Duy and I get lazy once in a while... BTW, nice strong motor you have.
It doesn't matter, as long as you use the same tester on all the motors... so it's consistant. Duy... nice sig Solid Alibye, thanks for typing all that up, Duy and I get lazy once in a while... BTW, nice strong motor you have.
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