WHAT IS BLOW BY?
 

on my civic when I remove the oil cap off the valve cover there is some blowby....what causes this no smoke though>?

Re: WHAT IS BLOW BY?
 

it`s normal to have a little bit form the oil cap.

blow by is caused by that tiny leakage from the rings during a compression stroke.

Re: WHAT IS BLOW BY?
 

my 97 accord stock has no blow by 130,000 miles but my turbo civic 140000 miles with motor swap at 100000 has a few squirts of oil from the oil cap when removed. The only smoke is from the muffler and i believe it is from being rich my af gauge is all the way in the rich zone, and the blackish gray vapor from the exhaust has condensation and makes your eyes burn...so is this type of blow back ok?Im running 5 psi,450cc dsms,uberdata

Re: WHAT IS BLOW BY?
 

oil coming out of the fill cap is normal, from all teh moving parts in teh head.

Re: WHAT IS BLOW BY?
 

should i still be able to feel air come out too?

Re: WHAT IS BLOW BY?
 

I can feel air coming out when I take my oil cap off... I thought that was normal?

If my rings are going anyways I'm going to crank up the boost and have fun with it while it lasts!

Re: WHAT IS BLOW BY?
 

blow by is when the pressure in the crank case blows up past the rings and causes oil to enter the combustion chamber (by passing through bad rings or cracked ring lands) and then the the smoke passes through the valves and come out the valve cover breather and exhaust. yes, if your car is running and you remove your oil cap, it is normal to have a little smoke (most heat and condensation) come out, as well as a little oil flinging around and air pulsing out, you have a cam or two in there moving at least 1200 or so rpm's at idle, don't expect everything around it (oil and air) to sit still as well ;)

Re: WHAT IS BLOW BY?
 

the cams move slower than the crank does :)

Re: WHAT IS BLOW BY?
 

Good explanation! ;) ;D


JP

Re: WHAT IS BLOW BY?
 

i thought a blow by was when you fart stinks really bad because it "blows by" your ---- on the way out?