Air out the Cap

Post by **frapjap** » Fri Oct 01, 2004 5:33 pm

A friend of mine has an SR that when you take off the oil cap while running, you get a...much more than usual amount of air flowing out of it. You could blow up a balloon pretty quickly... Is this prominetly from bad seals, or is there something bigger at hand here?

Post by **Onizuka** » Fri Oct 01, 2004 7:22 pm

I tryed pouring oil additive into the KA24DE while it was running once, the oil seems to just float their for a few seconds until the air venting from head pushed it away and it got all over the place. Your crank case and head are not sealed. You dont want air pressure in the block, so it is vented (from both the block behind and beneath the 4th exaust runner and at the T on the valve cover). Now if you just leave the vent open, oil vapor will slowly coat the entire inside of your engine bay, which is why its a good idea to get a cheap oil catch can.

If your freind capped or sealed off any of the vent tubes this may be causing the rappid air movement.

Plus im pretty sure your not supposed to run the motor without a oil cap on it

Post by **Jesse SR20** » Sat Oct 02, 2004 6:48 am

An excessive amount of air out of the valve cover could be an indication of piston blow-by.

Piston rings not seating or being worn out, or piston ring lands being broken are all causes of this. Do a compression test, or a leakdown if you can.

Post by **Cyberkreig** » Sat Oct 02, 2004 6:52 am

I guess it could be a bad thing.. but i've never seen a motor running with a oil cap off that wasnt moving ALOT of air. Enought that if you tried to pour in even heavy oil it would just blow all over you.

Post by **frapjap** » Sat Oct 02, 2004 11:02 am

So we've basically come to the conclusion that the vent tubes could have been sealed (is this a normal procedure from a shop as well?) OR that the piston rings and/or land rings are damaged?

In which case, if the tubes are sealed, this isn't a huge issue. But if the rings are bad (which we will find out soon when we rebuild the motor, the procedure was definitely worth doing?

Post by **240Kuminachu** » Tue Oct 05, 2004 2:05 pm

They all do this, my motor is rebuilt and it does it. Every one take off your oil cap while your car is running, it will do it too. Its normal

Air out the Cap

Air out the Cap

Re: Air out the Cap (frapjap)

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