compression test on motorset - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

angel mkiv · 01-05-2010, 02:54 AM

hey theres this guy selling his s13 sr20det motorset and it sits without a radiator setup or a intercooler and i wanted to do a compression test on the motor but dont know how to do it when the motor is out..any help on how to do it?and it does have the tranny mated to it..thanks

Hashiriya415 · 01-05-2010, 03:29 AM

No difference between in the car or outside, just crank the starter and have the throttle open. I assume you know about disconnecting ignition and fuel with CAS

jester757 · 01-06-2010, 07:39 PM

Cold compression tests can be faked by adding oil or whatever to make a seal and up the compression. Make sure you trust the guy or watch out. Warm compression tests are the way to go. When i was importing clips, I ran all the motors to ensure an accurate test. Look down in the cylinder with a bright flash light - if you see shinny oil on the pistons run away. A good warm number if I remember well was about 150-160. I think the factory manual says 165 is what the compression was when the motor was "new." The procedure can be found in any of the FSM that you can download for free.

Propaganda · 01-06-2010, 08:29 PM

156 Standard
128 Minimum
14 difference between cylinders

If you can, do a leak down test instead

angel mkiv · 01-06-2010, 09:17 PM

alright thanks for the tips and well ima just first do the compression test and if it passes with good numbers then il take it to the next step and take it to my firends house since he has a air compressure and do the leakage test..and after it passes both il hand over the cash...but whats the max percentage of leakage it for it to be fine..or it has to stay at 0% unless its a fixable leak???thanks

01-05-2010, 02:54 AM	#1
angel mkiv Zilvia Addict Join Date: Sep 2009 Location: Seattle, wa Posts: 727 Trader Rating: (4) Feedback Score: 4 reviews	compression test on motorset hey theres this guy selling his s13 sr20det motorset and it sits without a radiator setup or a intercooler and i wanted to do a compression test on the motor but dont know how to do it when the motor is out..any help on how to do it?and it does have the tranny mated to it..thanks

01-05-2010, 03:29 AM	#2
Hashiriya415 Zilvia FREAK! Join Date: Jun 2007 Location: San Francisco Age: 36 Posts: 1,007 Trader Rating: (22) Feedback Score: 22 reviews	No difference between in the car or outside, just crank the starter and have the throttle open. I assume you know about disconnecting ignition and fuel with CAS

01-06-2010, 07:39 PM	#3
jester757 Join Date: May 2009 Location: Atlanta, GA Posts: 40 Trader Rating: (2) Feedback Score: 2 reviews	Cold compression tests can be faked by adding oil or whatever to make a seal and up the compression. Make sure you trust the guy or watch out. Warm compression tests are the way to go. When i was importing clips, I ran all the motors to ensure an accurate test. Look down in the cylinder with a bright flash light - if you see shinny oil on the pistons run away. A good warm number if I remember well was about 150-160. I think the factory manual says 165 is what the compression was when the motor was "new." The procedure can be found in any of the FSM that you can download for free.

01-06-2010, 08:29 PM	#4
Propaganda Zilvia Junkie Join Date: May 2005 Location: Charleston, SC Age: 37 Posts: 451 Trader Rating: (10) Feedback Score: 10 reviews	156 Standard 128 Minimum 14 difference between cylinders If you can, do a leak down test instead

01-06-2010, 09:17 PM	#5
angel mkiv Zilvia Addict Join Date: Sep 2009 Location: Seattle, wa Posts: 727 Trader Rating: (4) Feedback Score: 4 reviews	alright thanks for the tips and well ima just first do the compression test and if it passes with good numbers then il take it to the next step and take it to my firends house since he has a air compressure and do the leakage test..and after it passes both il hand over the cash...but whats the max percentage of leakage it for it to be fine..or it has to stay at 0% unless its a fixable leak???thanks