Oil and air blowing from valve cover?? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Muzzy · 08-25-2003, 05:18 PM

ok...when i take my oil cap off with the car running...should it be blowing a lot of air out an adition to oil? (my idle is bout 1k)
wut causes this or could cause this??

it doesnt blow that hard from the breather though

zero.counter · 08-25-2003, 05:22 PM

Its possible that oil might be leaking past the valves and running a compression test might tell if you have a leak. Also, when those parts move under the valve cover, some movement must be generated and gas release is a bi-product, but not too much.

Bill Roberts · 08-25-2003, 06:41 PM

Don't run your car with the oil cap off!!

Most of the pressure you feel is OIL PRESSURE as the oil pump is pumping oil to the top end to lubercate your camshaft, rockers etc..

Their also is crankcase ventalation properties not being fed properly by exposing that "hole". You will notice exhaust noise as well because the oil that is being pumped to the top end ...the system is now "vented" and you are actually hearing some of the sound traveling through the oil pumping system from the bottom end!

Ever looked at the oil pressure gauge when you open the cap on a running engine with overhead cams? With this in mind...the oil that is coming out of the hole is being pumped to the top and slung around by the top end moving parts..you gave it a place to go. Oil goes out the hole where the cap was. This is not an in-block cam engine.

The oil pressure system is a closed loop. You opened that loop with the cap off. Not a good thing to do on an overhead cam engine. You did not hurt anything for a short time but the cap has a seal on it (dipstick too) for that very reason to keep the oil pumping system closed and SEALED!

Crankcase ventalation (pressure) is carefully bled off by the PCV valve (kinda like a BOV for block pressure) PCV=Positive crankcase ventalation.

Muzzy · 08-25-2003, 06:45 PM

well according to my dad it didnt blow that hard before (after i went racin) which i think is irrelevent cuz i go that fast on the highway 70-85 (texas thas y) so i dont see how that would cause it

Bill Roberts · 08-25-2003, 06:46 PM

Why run your car at all with the oil cap off?

Read my post carefully and comprehend the physics.

Muzzy · 08-25-2003, 06:55 PM

aaahhhhaa ic..ok..i jus replaced my PCV valve too...but y would it blow harder now...if it really is and not my dads imagination

Bill Roberts · 08-25-2003, 07:05 PM

Good, you see the correlation. At the oil pressures our cars run at (up to 80LBS)..that is alot of pressure by the oil pump.

You vent the oil pressure by opening the system in an UNintended way. You also get oil...all over.

70-85 is not running our cars fast or hard at all...running 85 to 90 in 3rd gear for a long period of time with a manual 5speed..is running it hard. Actually, Our cars can run at 110MPH in 5th gear all day long with no problems. I think once it was mentioned a bone stock 240SX was ran at 115 for 24 hrs..only stopping for fuel..for test purposes. No problem...of course, the brakes are the weak link on our cars. They cannot take repeated stops from 90 MPH over and over without fading out totally and burning to a crisp...warping the rotors.

Brake upgrades are essential if you travel above 85MPH and want braking power. Of course, do it on da track..

Don't run it with the oil cap off.....

Muzzy · 08-25-2003, 07:10 PM

lol ok...once again... thanks bill...see we need u
and u cant live with out zilva.net and we all need u

zero.counter · 08-26-2003, 04:25 PM

Quote:

Originally posted by Muzzy
lol ok...once again... thanks bill...see we need u
and u cant live with out zilva.net and we all need u

....

Read my post again, the last sentence.

I said that but short and sweet. Oh well, no love for this n1@@a.

Muzzy · 08-26-2003, 09:42 PM

sissy i saw that!!

u didnt say anything about oil comin out...u jus said gases

Bill Roberts · 08-26-2003, 09:53 PM

I take a case quarter and a date with Zero for fun.

zero.counter · 08-26-2003, 10:06 PM

Muzzy · 08-26-2003, 10:20 PM

¿wut?

zero.counter · 08-26-2003, 10:35 PM

Quote:

Originally posted by Muzzy
¿wut?

*DSC* · 08-26-2003, 10:52 PM

Quote:

Originally posted by Bill Roberts
...of course, the brakes are the weak link on our cars. They cannot take repeated stops from 90 MPH over and over without fading out totally and burning to a crisp...warping the rotors.

Brake upgrades are essential if you travel above 85MPH and want braking power. Of course, do it on da track..

Yeah...I'm gona have to go ahead and umm disagree with you on that one... </office space>

I've done 10-60-10 (not quite 60, closer to 58...kept it in 2nd gear) tests on my car as fast as it could go and with new (broken in and 1 day old) $10 pads and old brown fluid it took 5 or 6 stops to start losing pedal pressure. Pads were smoking and fluid boiled. At that point I could still stop but it wasn't at a safe rate.
With good street/track pads and fresh fluid, the 240 brakes are fine. They may not be the most powerful, especially with wider/stickier tires but they won't crap out on you like your saying. Add, SS lines and your even better. 2" or larger brake ducts and I bet you won't be able to make them fade if you tried.

Bill you seem full of great info, but I must question your experience after this one...

BTW: I've done a good ammount off 100+mph to under 50mph stops on track with street/track pads, new fluid and ss lines (no ducts) and they hold up just fine...

Bill Roberts · 08-27-2003, 04:17 PM

I should have worded it...You can't rally race for 30 mins to an hour with stock brakes...or try to stop from over 100MPH more than a couple of times. This said..and I rally race..means the stock brakes are inadaquate for this application.

The way it is with my car, it does not take much to ruin a new set of rotors and pads. The rears hold up pretty good, the fronts cannot hang.

08-25-2003, 05:18 PM	#1
Muzzy Zilvia FREAK! Join Date: Jan 2003 Location: TX Posts: 1,555 Trader Rating: (0) Feedback Score: 0 reviews	Oil and air blowing from valve cover?? ok...when i take my oil cap off with the car running...should it be blowing a lot of air out an adition to oil? (my idle is bout 1k) wut causes this or could cause this?? it doesnt blow that hard from the breather though __________________ lemme have a dollar

08-25-2003, 06:41 PM	#3
Bill Roberts Zilvia FREAK! Join Date: May 2003 Location: S FL. Posts: 1,538 Trader Rating: (0) Feedback Score: 0 reviews	Don't run your car with the oil cap off!! Most of the pressure you feel is OIL PRESSURE as the oil pump is pumping oil to the top end to lubercate your camshaft, rockers etc.. Their also is crankcase ventalation properties not being fed properly by exposing that "hole". You will notice exhaust noise as well because the oil that is being pumped to the top end ...the system is now "vented" and you are actually hearing some of the sound traveling through the oil pumping system from the bottom end! Ever looked at the oil pressure gauge when you open the cap on a running engine with overhead cams? With this in mind...the oil that is coming out of the hole is being pumped to the top and slung around by the top end moving parts..you gave it a place to go. Oil goes out the hole where the cap was. This is not an in-block cam engine. The oil pressure system is a closed loop. You opened that loop with the cap off. Not a good thing to do on an overhead cam engine. You did not hurt anything for a short time but the cap has a seal on it (dipstick too) for that very reason to keep the oil pumping system closed and SEALED! Crankcase ventalation (pressure) is carefully bled off by the PCV valve (kinda like a BOV for block pressure) PCV=Positive crankcase ventalation. Last edited by Bill Roberts; 08-25-2003 at 06:45 PM..

08-25-2003, 06:45 PM	#4
Muzzy Zilvia FREAK! Join Date: Jan 2003 Location: TX Posts: 1,555 Trader Rating: (0) Feedback Score: 0 reviews	well according to my dad it didnt blow that hard before (after i went racin) which i think is irrelevent cuz i go that fast on the highway 70-85 (texas thas y) so i dont see how that would cause it __________________ lemme have a dollar

08-25-2003, 06:55 PM	#6
Muzzy Zilvia FREAK! Join Date: Jan 2003 Location: TX Posts: 1,555 Trader Rating: (0) Feedback Score: 0 reviews	aaahhhhaa ic..ok..i jus replaced my PCV valve too...but y would it blow harder now...if it really is and not my dads imagination __________________ lemme have a dollar

08-25-2003, 07:10 PM	#8
Muzzy Zilvia FREAK! Join Date: Jan 2003 Location: TX Posts: 1,555 Trader Rating: (0) Feedback Score: 0 reviews	lol ok...once again... thanks bill...see we need u and u cant live with out zilva.net and we all need u __________________ lemme have a dollar

08-25-2003, 05:22 PM	#2
zero.counter Nissanaholic! Join Date: Jun 2003 Location: At work Posts: 2,003 Trader Rating: (0) Feedback Score: 0 reviews	Its possible that oil might be leaking past the valves and running a compression test might tell if you have a leak. Also, when those parts move under the valve cover, some movement must be generated and gas release is a bi-product, but not too much.

08-25-2003, 06:46 PM	#5
Bill Roberts Zilvia FREAK! Join Date: May 2003 Location: S FL. Posts: 1,538 Trader Rating: (0) Feedback Score: 0 reviews	Why run your car at all with the oil cap off? Read my post carefully and comprehend the physics.

08-25-2003, 07:05 PM	#7
Bill Roberts Zilvia FREAK! Join Date: May 2003 Location: S FL. Posts: 1,538 Trader Rating: (0) Feedback Score: 0 reviews	Good, you see the correlation. At the oil pressures our cars run at (up to 80LBS)..that is alot of pressure by the oil pump. You vent the oil pressure by opening the system in an UNintended way. You also get oil...all over. 70-85 is not running our cars fast or hard at all...running 85 to 90 in 3rd gear for a long period of time with a manual 5speed..is running it hard. Actually, Our cars can run at 110MPH in 5th gear all day long with no problems. I think once it was mentioned a bone stock 240SX was ran at 115 for 24 hrs..only stopping for fuel..for test purposes. No problem...of course, the brakes are the weak link on our cars. They cannot take repeated stops from 90 MPH over and over without fading out totally and burning to a crisp...warping the rotors. Brake upgrades are essential if you travel above 85MPH and want braking power. Of course, do it on da track.. Don't run it with the oil cap off.....

08-26-2003, 09:42 PM	#10
Muzzy Zilvia FREAK! Join Date: Jan 2003 Location: TX Posts: 1,555 Trader Rating: (0) Feedback Score: 0 reviews	sissy i saw that!! u didnt say anything about oil comin out...u jus said gases __________________ lemme have a dollar

08-26-2003, 09:53 PM	#11
Bill Roberts Zilvia FREAK! Join Date: May 2003 Location: S FL. Posts: 1,538 Trader Rating: (0) Feedback Score: 0 reviews	I take a case quarter and a date with Zero for fun.

08-26-2003, 10:06 PM	#12
zero.counter Nissanaholic! Join Date: Jun 2003 Location: At work Posts: 2,003 Trader Rating: (0) Feedback Score: 0 reviews	....

08-26-2003, 10:20 PM	#13
Muzzy Zilvia FREAK! Join Date: Jan 2003 Location: TX Posts: 1,555 Trader Rating: (0) Feedback Score: 0 reviews	¿wut? __________________ lemme have a dollar

08-27-2003, 04:17 PM	#16
Bill Roberts Zilvia FREAK! Join Date: May 2003 Location: S FL. Posts: 1,538 Trader Rating: (0) Feedback Score: 0 reviews	I should have worded it...You can't rally race for 30 mins to an hour with stock brakes...or try to stop from over 100MPH more than a couple of times. This said..and I rally race..means the stock brakes are inadaquate for this application. The way it is with my car, it does not take much to ruin a new set of rotors and pads. The rears hold up pretty good, the fronts cannot hang. Last edited by Bill Roberts; 08-27-2003 at 04:30 PM..