Compresion test

Post by **Powder** » Wed Apr 09, 2003 5:50 pm

Ok i think i have decided to keep the ka anyone know where i can get a compresion test done in fl? I have about 5-6k to spend on my motor what could i do with it?

Post by **Trigger** » Wed Apr 09, 2003 5:50 pm

if you can drive to pensacola i can take a compression test for ya. Its not hard to do. But most any dealer will do the test for you.

Tim

YouTube · Post by **EZcheese15** » Wed Apr 09, 2003 5:50 pm

You can buy a compression tester for like $20-$30 at nearly any autoparts store. The only other thing you'll need is a spark plug socket, extension, and socket wrench.

Post by **red240ne** » Wed Apr 09, 2003 5:50 pm

Yea, it's not hard at all. Take out one spark plug at a time, and screw the tester in there. Remember to relieve fuel pressure before the test. Crank the car over for about 3-4 seconds(have throttle wide open while doing this) or whenever the tester is maxed out, and you have your reading. Do each cylinder about 3 times.

Post by **encasemyheart** » Wed Apr 09, 2003 5:50 pm

I'm having a special at my house in Houston (if you want to drive) $1500 for a compression test, but you get an engine rebuild for free if you supply me the parts.

Post by **95_240sx** » Wed Apr 09, 2003 5:50 pm

Come to Oregon and Ill take you up on it

Rick

Post by **AceInhole** » Wed Apr 09, 2003 5:50 pm

red240ne wrote:Yea, it's not hard at all. Take out one spark plug at a time, and screw the tester in there. Remember to relieve fuel pressure before the test. Crank the car over for about 3-4 seconds(have throttle wide open while doing this) or whenever the tester is maxed out, and you have your reading. Do each cylinder about 3 times.

FSM states to have all plugs removed, and injectors unplugged.

YouTube · Post by **EZcheese15** » Wed Apr 09, 2003 5:50 pm

AceInhole wrote:FSM states to have all plugs removed, and injectors unplugged.

Instead of unplugging the injectors, you can just pull the fuel pump fuse. It's easier

Does the same thing.

Post by **Powder** » Wed Apr 09, 2003 5:50 pm

ok lets say my compresion test turned out good what could i do to my engine for around 5k?

Post by **AceInhole** » Wed Apr 09, 2003 5:50 pm

EZcheese15 wrote:Instead of unplugging the injectors, you can just pull the fuel pump fuse. It's easier Does the same thing.

true.... but your injectors might still allow fuel to enter the engine as there would still be a pressure difference between the rail and the intake (since your intake manifold and runners are under some vacuum when cranking). plus pulling the injector plugs is easier, to me at least.

Quote » ok lets say my compresion test turned out good what could i do to my engine for around 5k?[/quote]A lot. for 5k your compression might not matter much if you could find someone to rebuild your engine for a few grand. Of course, you could just spend the money on a pre-made kit and run up to 10psi safely.

Post by **S13Ka24e** » Wed Apr 09, 2003 5:50 pm

Powder wrote:ok lets say my compresion test turned out good what could i do to my engine for around 5k?

I would go for nsport stage 2 just for the customer support, if you have a problem you can just call them up and they will help you. Of couse you could get more for less money, but if you don't know much about turboing a car i would suggest a kit for the customer support will help.

Post by **tapdeznutz** » Wed Apr 09, 2003 5:50 pm

u guys are going about it all wrong with the compression test. just unplug the ignition coil. no spark no start. no matter fuel or not. but it would be a good idea to also pull the fuel pump fuse also.

jay

Post by **oi138** » Wed Apr 09, 2003 5:50 pm

tapdeznutz wrote:u guys are going about it all wrong with the compression test. just unplug the ignition coil. no spark no start. no matter fuel or not. but it would be a good idea to also pull the fuel pump fuse also.

jay

Well when you take out all of the spark plugs you don't have to unplug the coil because no spark will be getting to the engine anyway.And yes fuel does matter. If you're pumping fuel through the engine it will get inside the compression tester and screw up the test results.best thing to do is. pull the fuel pump fuse. run the car until it dies. then take out the plugs and disconnect injecors. that way you are sure you have no fuel coming in.

Post by **AceInhole** » Wed Apr 09, 2003 5:50 pm

oi138 wrote:Well when you take out all of the spark plugs you don't have to unplug the coil because no spark will be getting to the engine anyway.And yes fuel does matter. If you're pumping fuel through the engine it will get inside the compression tester and screw up the test results.best thing to do is. pull the fuel pump fuse. run the car until it dies. then take out the plugs and disconnect injecors. that way you are sure you have no fuel coming in.

well, if you disconnect the injectors, no fuel will come in anyways. no need to depressurize the fuel rail.

and if you don't take out the other spark plugs, you WILL end up with lower comp numbers, as the compression stroke will make it harder for the starter to crank, and gain the necessary "speed" (300rpms is what the test is supposed to be done at IIRC). I'm wondering if some people with low comp numbers have such numbers because of an error like that.

YouTube · Post by **EZcheese15** » Wed Apr 09, 2003 5:50 pm

AceInhole wrote:well, if you disconnect the injectors, no fuel will come in anyways. no need to depressurize the fuel rail.

and if you don't take out the other spark plugs, you WILL end up with lower comp numbers, as the compression stroke will make it harder for the starter to crank, and gain the necessary "speed" (300rpms is what the test is supposed to be done at IIRC). I'm wondering if some people with low comp numbers have such numbers because of an error like that.

True, but pulling the fuel pump fuse is easier on 99% of the cars out there. For instance, it takes me about 30 seconds to pull my fuel pump fuse and depressurize the fuel rail. It would take me probably 2 hours to disconnect the injectors (I have a sentra, but still). Just a universal word of advice

Post by **AceInhole** » Wed Apr 09, 2003 5:50 pm

EZcheese15 wrote:True, but pulling the fuel pump fuse is easier on 99% of the cars out there. For instance, it takes me about 30 seconds to pull my fuel pump fuse and depressurize the fuel rail. It would take me probably 2 hours to disconnect the injectors (I have a sentra, but still). Just a universal word of advice

heheh.... well, since the injectors are so easy to reach on a 240, you can just unplug the injectors in a few seconds and not worry about having to idle your car till it stalls, then cranking, then cranking again. :p

Post by **silviaNE** » Wed Apr 09, 2003 5:50 pm

before this gets ugly. Take all spark plugs out. That means make sure that the plugs are disconected from the plug wires to. (just in case you dont know that. no offense.) either disconect injectors, or my fravorite remove fuel pump fuse and crank any fuel left through the system. Then thread gauge adapter into first plug hole. have a friend crank the engine for 10 to 15 seconds with thier foot on the accelorator. (you must have engine at WOT to get a proper reading.) you can do this twice per cylinder if you like. Make sure to record your readings per cylinder and to remove pressure from gauge each time. do this for all 4 cylinders. When you have all your readings calculate them to make sure they are within 15% of each other. I would recomend that they be within 10% but 15% is ok just not great. Lets please give through and accurate responses to questions and not answer if we are not 100% sure. You can buy your own compression tester for 20 to 30 dollars and it will come with adapters to use on most cars, motorcycles and other misc engines. I know there have been a lot a responses to this post, but one is enough. I hope i have been able to help you, and i do not mean to offend anyone else

thanks

Post by **encasemyheart** » Wed Apr 09, 2003 5:50 pm

silviaNE wrote:before this gets ugly. Take all spark plugs out. That means make sure that the plugs are disconected from the plug wires to. (just in case you dont know that. no offense.)

And how do you propose taking out the spark plugs with the wires attached? either disconect injectors, or my fravorite remove fuel pump fuse and crank any fuel left through the system.

Also it gets the job odne faster if you remove the gas cap when depressurizing.Then thread gauge adapter into first plug hole. have a friend crank the engine for 10 to 15 seconds with thier foot on the accelorator. (you must have engine at WOT to get a proper reading.) you can do this twice per cylinder if you like.

Good advice, make sure and do it more than once, and if you get different readings do it again until you get similar readings. If there is oil in the cylinder or something it will show better results than are actually present.Make sure to record your readings per cylinder and to remove pressure from gauge each time. do this for all 4 cylinders. When you have all your readings calculate them to make sure they are within 15% of each other. I would recomend that they be within 10% but 15% is ok just not great. Lets please give through and accurate responses to questions and not answer if we are not 100% sure.

This is true, but like you I recommend 10%, but it's not like you can change anything with it. If you have any low readings pour about a capful of oil (a cap from the oil bottle) into the offending cylinder(s?) and retest them. If the results go back to spec after oil is added it sounds like your rings are going the way of the dinosaurs.You can buy your own compression tester for 20 to 30 dollars and it will come with adapters to use on most cars, motorcycles and other misc engines. I know there have been a lot a responses to this post, but one is enough. I hope i have been able to help you, and i do not mean to offend anyone else

There are a few different kinds of comp. testers. I have seen a couple where the tester just has a plastic grommet on the end and you just push it into the spark plug hole and hope you made a good seal. This kind is NOT IDEAL. Get the kind that we are talking about which screws into the actual hole and has adaptors. Good luck!!

Post by **silviaNE** » Wed Apr 09, 2003 5:50 pm

stupid questions get stupid answers.

enogh said

Post by **AceInhole** » Wed Apr 09, 2003 5:50 pm

You both failed to mention to warm the engine up, too. :p

Why is everyone so afraid to unplug the injectors? Ah well... so I dare to go against the FSM every once in a while.

YouTube · Post by **EZcheese15** » Wed Apr 09, 2003 5:50 pm

AceInhole wrote:You both failed to mention to warm the engine up, too.

Why is everyone so afraid to unplug the injectors?

Because the only car on the planet with injectors that are easy to get at is the 240SX. And these are all generic answers

I'm not afraid of unplugging the injectors, its just that I'm so used to doing the fuel pump fuse (on other cars), it becomes habit when I get to a 240SX. Either way works.

Post by **silviaNE** » Wed Apr 09, 2003 5:50 pm

why does is this post continuing? It has gone of track some time ago.

Post by **C-Kwik** » Wed Apr 09, 2003 5:50 pm

It started only a few days ago. If you want it to die, stop posting...

Post by **Thee 240sx Owner** » Wed Apr 09, 2003 5:50 pm

I'm posting now... any problems???

Post by **silviaNE** » Wed Apr 09, 2003 5:50 pm

i do like a good laugh. i almost forgot about this thread, might as well push it to the top for kicks.

Compresion test

Compresion test

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