s13 blacktop compression numbers and question.

[shinobis13hb]

s13 blacktop, 138km on cluster.

my car is currently at PIT garage for a s13 blacktop swap.
we did the compression test on one motor, numbers were about 140-145 in cyl1-3 NOW.. in cyl 4 the compression was about 120 or so give'r take a few higher.

Now they told me that the motor had been sitting for some time (front clip//motor had 7/7/10 on valve cover and motor starts ok) they told me because the motor has been sitting and the seals are dry that once the motor is in my car and all of the seals are lubed and warmed up my numbers will go higher.

i would like your guys imput.. my dad said that i should see better numbers. i do beleive them but i see videos on youtube of sr's getting 150+ but who knows if they have been sitting or if they have dropped oil in the head for better numbers.

[let5l1de]

120 is not good. Cylinders should not vary more than 10%. Now, many engine typically sit for some time and many scenarios may play games with a standard "compression tests" such as rust face of valve (condensation on an open valve), really dry rings/cylinder, debris in the chamber/cylinder. Have them perform a "cylinder leak down test". This will give you a better idea of where the improper seal within the cylinder or head may be located.

~mario
GR Performance

[shinobis13hb]

did they get a motor from you recently?
sr blacktop.
NOW they said they would compression check the motor after it is fired up and they drive it out for a test drive. if the compression numbers are still to low i will speak to the shop manager. they have not had 1 swap comeback as bad or anything. so ill take the word for it.
thanks for your help!
120 is not good. Cylinders should not vary more than 10%. Now, many engine typically sit for some time and many scenarios may play games with a standard "compression tests" such as rust face of valve (condensation on an open valve), really dry rings/cylinder, debris in the chamber/cylinder. Have them perform a "cylinder leak down test". This will give you a better idea of where the improper seal within the cylinder or head may be located.

~mario
GR Performance

[let5l1de]

They did not purchase the engine or engines from me. I have over 19 years experience in the automotive industry and over 15 years of hands on experience. I am simply offering help in your situation.

Have them do a leak down test which is not the same as a compression check. This will help identify and pinpoint the problem within the cylinder.

I understand there is always room for mechanical error with any used engine. People need to understand that engines do not just work or not work. There is so much gray in-between with used engines and most consumers are ignorant, misinformed or uneducated in identifying, diagnosing and understanding what buying a used engine really means.

Never take anyone's word unless they have earned your trust. lol...

~m

[let5l1de]

Just wondering what the outcome was with the leakdown test. BTW do you have a white hatch?

~m