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 240sx compression of 90ish psi across

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kouki_chee
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PostSubject: 240sx compression of 90ish psi across   Mon Jul 18, 2011 11:48 am

well i did a compression test on my 91 ka24de and it has a steady compression of 90ish all the way across... i put some oil down the spark plug hole and retested it but still the same.... the funny thing is that it runs good and pulls alright so i dont think its anything like a headgasket... i really think its a timing issue because as i stated somewhere else on here my chain was loose... any one know if theres a good write up with pictures on how to replace a timing chain??? anyone would like to help?? maybe if i cant be there to help i can pay cash
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93sapphirecoupe
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PostSubject: Re: 240sx compression of 90ish psi across   Mon Jul 18, 2011 12:09 pm

did you do it cold or hot?
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theboy
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PostSubject: Re: 240sx compression of 90ish psi across   Mon Jul 18, 2011 12:14 pm

timing wouldnt cause your compression to be half of what it should be. Your issue is probably rings, ring lands, or head gasket.

Zilvia has write ups on how to do it but you gotta search. If you need help doing it, you can always pm me here and ill walk you through it. Just be ready to lift the motor cause you have to drop the oil pan to remove the front cover. your basically going to be taking your motor down to a short block and rebuilding. So make sure you get every gasket possible.

Side note: when you "thought" your timing chain was "loose" did it sound like a bunch of marbles being shaken in a coffee can?
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kouki_chee
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PostSubject: Re: 240sx compression of 90ish psi across   Mon Jul 18, 2011 2:10 pm

i did the compression while it was hot... i had to drive the car to get the compression tester... i was thinking it was rings or head gasket but it when i put oil down to see if it would seal for a bit and raise the compression, it didnt.... i dont know if it is a head gasket but i thought if it was i would have oil in my coolant and the compression wouldnt be so flat cross... maybe like 123, 80,89, 100 for example not 90, 90, 91,90... correct me if im wrong... idk if i have to redo alot and its going to cost me more then $400 to do it, i might just look for a lower mile ka24de with good compression and chain... lol
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kouki_chee
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PostSubject: Re: 240sx compression of 90ish psi across   Mon Jul 18, 2011 2:19 pm

i was thinking it was a timing issue because it doesnt really knock more like when u drive it and have it in after 3krpm, u can hear a clicking... more like the valves arent shut all the way
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theboy
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PostSubject: Re: 240sx compression of 90ish psi across   Mon Jul 18, 2011 3:01 pm

in theory, and depending on how bad the head gasket/head/block surface is, the compression test could show a wide range of values. And you are correct that you could find coolant in the oil. But usually on a ka, if the compression numbers are even and low across the board, its the piston rings. If it were the head gasket, youd see white smoke/steam coming out the exhaust. If the timing chain guides are bad youll hear the chain rattle at idle and it literally sounds like a handful of marbles in an old metal coffee can. Those usually go bad before the chain stretches. This is also what usually causes the chain to stretch.

As for you timing theory, it could be off. But if it is, youll notice a lack of power, crappy response, and a bad idle.

If you want a low mile dohc ive got one for sale. Head studs and fresh gaskets.
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240sxguy
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PostSubject: Re: 240sx compression of 90ish psi across   Mon Jul 18, 2011 3:11 pm

Were you holding the throttle open when doing the test? It's inaccurate if you don't.
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Secret Squirrel
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PostSubject: Re: 240sx compression of 90ish psi across   Mon Jul 18, 2011 4:12 pm

^^^ THIS
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kouki_chee
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PostSubject: Re: 240sx compression of 90ish psi across   Mon Jul 18, 2011 5:34 pm

my chain guides are removed but my tensioners might be bad....what do you mean headstuds and fresh gaskets???? pm me please... maybe we could work something out but your kinda far from me... lol

yes i had the peddle all the way down to the floor
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theboy
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PostSubject: Re: 240sx compression of 90ish psi across   Tue Jul 19, 2011 6:58 am

i mean it has ARP head studs instead of stock bolts because i was going to turbo it but ended up getting a built short block and used that instead. While i was putting the studs in, i also replaced all the gaskets with new ones and just cleaned stuff up and to make sure it was good to go on start up. Its all stock, just been freshened up.
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kouki_chee
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PostSubject: Re: 240sx compression of 90ish psi across   Tue Jul 19, 2011 8:33 pm

pm me price and info...
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kouki_chee
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PostSubject: Re: 240sx compression of 90ish psi across   Thu Jul 21, 2011 4:34 pm

ok i have a question on my cluster too... my mph gauge didnt work so i swapped it out to a sohc mph gauge... it works now but at idle the needle is at 10mph... when i drive it around 30-40 mph it says im going 50ish??? also the needle doesnt go down fast as it should if it even goes down
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theboy
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PostSubject: Re: 240sx compression of 90ish psi across   Fri Jul 22, 2011 7:05 am

it probably wasnt your cluster that was bad, it sounds like your speed sensor on the trans is bad.
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