HELP plz! S14 SR Compression test..good? bad? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Driftacular · 11-08-2009, 06:04 PM

Hey!
so in short im looking to buy this S14 SR tmrw mayb
so its already in a S14, runs fine, boosts fine, no misfires, no problems..
Has 35,000km on it from a halfcut.
BUT....
the turbo seal is going soon, and its getting oil passed through... the owner has been topping it up every once in a while making sure its not going down..(turbo is not a problem for me though)

So i decided to do a compression test today on it
and the results:
131-131-130-127

Good ? Bad? wats ur take?

Ive read its supposed to be up by the 150 mark...

going to try a leakdown test tmrw too...

kushlivin · 11-08-2009, 06:07 PM

thats pretty low in my opinion

sil80 monster · 11-08-2009, 06:19 PM

Quote:

Originally Posted by kushlivin

thats pretty low in my opinion

^^ i second that

Sileighty_85 · 11-08-2009, 06:26 PM

did you pull ALL the plugs and crank it at WOT until it stops rising?

I have a buddy thats like that still drives fine.

Ive heard ppl say that its not that bad as long as the number are close together.......

Propaganda · 11-08-2009, 06:56 PM

Minimum is 128. Difference between cylinders is 14.

I say it's okay.. up to you

ericb382 · 11-08-2009, 07:10 PM

I compression tested my motor with my cheap checker compression gauge. Numbers were lower than I liked so I retested with a coworker's snap-on compression tester. Gained 10psi accross the board on the same day using the same method, back to back....

That being said, the nubers you posted are a little lower than I would like to see, but by no means is it a sign of an obviously weak motor.

Did you also wait for the motor to warm up first and make sure no fuel was injecting.

blackhole · 11-08-2009, 07:15 PM

Bad oil rings, anything at or below needs to be rebuilt, redo compression pour a little oil down each cylinder to see if your readings change, if your readings go up your valve seals are bad if your readings stay the same bad oil rings.

Good luck! I would not take the chance on low compression all points to major work in the future, save your self the headake

Sileighty_85 · 11-08-2009, 07:35 PM

Quote:

Originally Posted by blackhole

Bad oil rings, anything at or below needs to be rebuilt, redo compression pour a little oil down each cylinder to see if your readings change, if your readings go up your valve seals are bad if your readings stay the same bad oil rings.

You got it backwards/ kinda wrong

Adding oil and it raising = Worn/Damaged Piston Rings
Adding oil and staying the same = Worn/sticking valves (improper Seating)

Driftacular · 11-08-2009, 07:49 PM

well the comp tester wasnt a snap-on.. was 60$ though? i dono if thats bad.. or good.. wasnt my comp tester...

she does have 35K on her.. seems pretty low to have such a problem..
any other ways to tell for this problem?

ericb382 · 11-08-2009, 09:14 PM

Leakdown, and/or like mentioned try a cap full of oil. If it's worn rings the oil will help them seal. If you see a difference greater than 5psi that's your culprit.

11-08-2009, 06:04 PM	#1
Driftacular Join Date: Mar 2009 Location: Toronto Posts: 21 Trader Rating: (0) Feedback Score: 0 reviews	HELP plz! S14 SR Compression test..good? bad? Hey! so in short im looking to buy this S14 SR tmrw mayb so its already in a S14, runs fine, boosts fine, no misfires, no problems.. Has 35,000km on it from a halfcut. BUT.... the turbo seal is going soon, and its getting oil passed through... the owner has been topping it up every once in a while making sure its not going down..(turbo is not a problem for me though) So i decided to do a compression test today on it and the results: 131-131-130-127 Good ? Bad? wats ur take? Ive read its supposed to be up by the 150 mark... going to try a leakdown test tmrw too...

11-08-2009, 06:26 PM	#4
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	did you pull ALL the plugs and crank it at WOT until it stops rising? I have a buddy thats like that still drives fine. Ive heard ppl say that its not that bad as long as the number are close together....... __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

11-08-2009, 06:56 PM	#5
Propaganda Zilvia Junkie Join Date: May 2005 Location: Charleston, SC Age: 38 Posts: 451 Trader Rating: (10) Feedback Score: 10 reviews	Minimum is 128. Difference between cylinders is 14. I say it's okay.. up to you

11-08-2009, 07:10 PM	#6
ericb382 Zilvia Member Join Date: Oct 2005 Location: Mesa, Az Posts: 293 Trader Rating: (4) Feedback Score: 4 reviews	I compression tested my motor with my cheap checker compression gauge. Numbers were lower than I liked so I retested with a coworker's snap-on compression tester. Gained 10psi accross the board on the same day using the same method, back to back.... That being said, the nubers you posted are a little lower than I would like to see, but by no means is it a sign of an obviously weak motor. Did you also wait for the motor to warm up first and make sure no fuel was injecting.

11-08-2009, 07:15 PM	#7
blackhole Join Date: Oct 2008 Location: Casselberry FL Age: 50 Posts: 41 Trader Rating: (0) Feedback Score: 0 reviews	Bad oil rings, anything at or below needs to be rebuilt, redo compression pour a little oil down each cylinder to see if your readings change, if your readings go up your valve seals are bad if your readings stay the same bad oil rings. Good luck! I would not take the chance on low compression all points to major work in the future, save your self the headake

11-08-2009, 07:49 PM	#9
Driftacular Join Date: Mar 2009 Location: Toronto Posts: 21 Trader Rating: (0) Feedback Score: 0 reviews	well the comp tester wasnt a snap-on.. was 60$ though? i dono if thats bad.. or good.. wasnt my comp tester... she does have 35K on her.. seems pretty low to have such a problem.. any other ways to tell for this problem?

11-08-2009, 09:14 PM	#10
ericb382 Zilvia Member Join Date: Oct 2005 Location: Mesa, Az Posts: 293 Trader Rating: (4) Feedback Score: 4 reviews	Leakdown, and/or like mentioned try a cap full of oil. If it's worn rings the oil will help them seal. If you see a difference greater than 5psi that's your culprit.