SR20 Blowby

[Frostitute]

I'm not sure if the correct term to use is "Blowby" but it's what I've been told it is. Just checking to see if its normal because I've had people tell me its bad and I would need a head rebuild and others tell me its normal so I just need some opinions.

Basically whilst the car is running, taking off the oil cap and putting your hand over it, There is alot of air coming out, and I mean alot. I've compared it with other SR20's and they all blow a tiny bit of air but not as much as mine is. Now I don't know if this is normal for SR20's or not but checked a few RB's and 4L Falcon motors and none of them do it.

So I was wondering first of all, are SR20's meant to do that? If not what could be the problem or what problems can arise from it.

[MikeS14]

Every time a cylinder fires, a lot of cylinder pressure is created, and some slips past the sealing rings of the piston, and gets into the crankcase. This is called 'blow by'. It naturally increases with age as the cylinder rings wear.
Im guessing it has done a fair amount of kms?
If your concerned you could do a compression test which is a more accurate way to check the cylinder condition than feeling the air coming out.

[ovaxitd]

lifting an oil cap off any running sr20 is stupid... doesnt achive a thing... get it compression tested is only way to know your blow by.... if you have an aftermarket catch can thats filling up then that is another tell tail sign.... you will always get a little blow by in any engine..

[2jzlux]

also think of the cams spinning at the top of the motor.
feeling for blowby is more of an oldschool way of thinking

[Frostitute]

That's what I got told by the people at work to "feel" for it. Guess you learn something new everyday. Anyway thanks for the advice people probably going to get it compression tested and yeh the motor has done 223xxx kms. Which is alot but meh :-/ its n/a so I don't care too much lol. An N/A motor isn't even that expensive and if I ever had to get a new motor I would go DET anyway.

[ttomred4000]

cyinder leakdown test would also tell you if its breathing.

[Drift_R32]

used to have massive blowby on a Vl turbo motor...used to blow out the dip stick on boost, ran a catch up and a springs over the dip stick to vent air, all fixed haha

[Lump]

lifting an oil cap off any running sr20 is stupid... doesnt achive a thing... ..
wrong, if the blowby is bad enough doing it can help confirm it straight away, especially if its puffing blue smoke & it works on any motor.

[Lump]

I'm not sure if the correct term to use is "Blowby" but it's what I've been told it is. Just checking to see if its normal because I've had people tell me its bad and I would need a head rebuild
not a head rebuild, more like new rings & check the cylinder bores for wear.
can be caused by faulty pcv system as well

[Quokka]

last comp i just realised that my engine is blow-by'in hardcore ways haha.. i dont have a catch can so intercooler is gettin filled with oil.. :s

how im going to fix it? add a catch can until the thing dies haha then replace engine

[Lump]

yeh, thats about all you can do

[ovaxitd]

a catch can that drails directly back to the sump is a goer for you if your happy to have blow by otherwise catch can needs to be emptied freq

[Quokka]

emptied back into engine where it belongs ;) haha

[Frostitute]

emptied back into engine where it belongs ;) haha

you made me conjure up this weird thought in my mind of me yelling at a catch can and saying...GET BACK IN THE MOTOR!!!