Take the oil cap off when its running, do you have air?
 

I have heard that you can see how much blowby your car has by taking off the oil cap and feeling the ammount of air that comes thru.

problem is that every Honda I have done this to has air coming thru. my 98 ex with 118k (uses 1/2 quart every 7000mi) , a friends 98 ex (turbo) w/ less than 10k on the motor, a 91 1.5 Hatch w/200k mi. All of them have air coming out (quite a bit). When compared to any push rod engine, they dont have any. Even my girlfriends Bonneville with 275k miles on it, not a puff of air. LT1 camaro thats been abused heavily, not a puff of air.

So I started thinking that maybe because its an Overhead cam you just get more air? Because every pushrod I have done that to has little to no air coming out. Every OHC motor I have done this to has a noticeable amount.

So whats the dilly yo? Is this any indication of ring condition at all? or just a myth? Where does it actually come from? Because my car runs fine, doesn't burn oil, passes emissions testing with flying colors.

Re: Take the oil cap off when its running, do you have air? (flood)
 

I pulled my oil cap off once while the car was running and got spattered with oil. Now I tend to shut the car off first. https://honda-tech.com/forums/images...es/emsmile.gif

98 d16y8 w/ 55k on the ticker!

Re: Take the oil cap off when its running, do you have air? (jlacoy82)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jlacoy82 &raquo;</TD></TR><TR><TD CLASS="quote">I pulled my oil cap off once while the car was running and got spattered with oil. Now I tend to shut the car off first. https://honda-tech.com/forums/images...es/emsmile.gif

98 d16y8 w/ 55k on the ticker!</TD></TR></TABLE>

but you wont feel the puff of air with the motor off! https://honda-tech.com/forums/images...s/emsmilep.gif

btw.. mine has air coming out of it also. i noticed it from the nipple on the valve cover. my compression numbers are okay and the car runs fine so who knows..

Re: Take the oil cap off when its running, do you have air? (_Edge.ONE)
 

That air pressure comes from the pistons moving up and down and pushing the crankcase air all around inside the engine. It is not an indication of blow-by, that's something that should be determined by a leak down test. You'll find some Volkswagens won't even run if you remove the oil cap because they rely on a certain internal pressure to run properly. Domestic cars will push air out the oil caps but because the engines are physically bigger inside, there's more room for the air to go, other than out the cap. Also a lot of domestic valve covers are baffled around the oil cap opening which would restrict the airs ability to go out that way when the cap is off.

Re: Take the oil cap off when its running, do you have air? (flood)
 

All Hondas do this

Re: Take the oil cap off when its running, do you have air? (00Red_SiR)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 00Red_SiR &raquo;</TD></TR><TR><TD CLASS="quote">That air pressure comes from the pistons moving up and down and pushing the crankcase air all around inside the engine. It is not an indication of blow-by, that's something that should be determined by a leak down test. </TD></TR></TABLE>

This makes sense to me. Thanks for the post.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by del_orson &raquo;</TD></TR><TR><TD CLASS="quote">
All Hondas do this</TD></TR></TABLE>

And I was starting to realize this, this just confirms it.


Thanks guys. I didn't think that it was a cheap and easy way to get out of a leakdown test but just wanted to ask around.

you don't wanna do this...you'll end up with oil stains all over your clothing like jlacoy82 said.

Re: (doughboy_88)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by doughboy_88 &raquo;</TD></TR><TR><TD CLASS="quote">you don't wanna do this...you'll end up with oil stains all over your clothing like jlacoy82 said.
</TD></TR></TABLE>

Um...already did it and contrary to popular belief there isn't much/any oil that came out. Its not like it gushes out, small droplets may be carried out by the air.

Anyways question already answered.

Re: (flood)
 

Re: (flood)
 

only happened once but i was putting out in with the car started (dumb a$$ move) so i had oil all over my new sum41 shirt.. o well i work at hot topic so i got a new one for nothing

Re: (weezo182)
 

Civic engines need blow-by for proper pressure in the intake manifold. The PCV takes the "blow-by" and put's it back into the intake manifold. With out blow-by there would be no Positive Cranckcase pressure. If your PCV is not working then you can notice that the engine idle's low, idle is all over the place and lacks power. Nothing to worry about.