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Old 08-26-2003, 06:11 PM   #1 (permalink)
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Default what can cause pressure under the valve cover?

first off, is there any oil pressure under our valve covers? and 2nd, what are some causes of this? i am not sure what is leaking oil in my car, but when i was out a few minutes ago running the car hard the blow by hose that connects both valve covers together blew off on the back side and oil is over everywhere? man this sucks. right before school starts too.
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Old 08-26-2003, 06:53 PM   #2 (permalink)
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do a search for pcv valve. Than when it shows something for an upgrade, read that. I have one extra if ya wanna buy it. It relieves the pressure from the crank case that causes oil to get in your intake and blow your dipstick out and whatnot
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Old 08-26-2003, 07:33 PM   #3 (permalink)
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well my damn car has never had a single problem in it's life and now it's leaking oil and leaking oil fast, coming from somewhere that is able to get it all over the timing belt and accessory belts and it's dripping somewhere near the oil filter location. wonder if the front main seal is bad would it be able to shoot all the oil on the belts?
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Old 08-26-2003, 08:45 PM   #4 (permalink)
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bad compression rings can cause excess pressure also... are you using oil normally?

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Old 08-26-2003, 09:12 PM   #5 (permalink)
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it's not really burning oil at all, i see a little in the intercooler pipes from the rear turbo, and in 2nd gear when i get on it full boost up at higher rpm's i think the rear turbo seal is bad and spurtin out some shit, although i run mobile 1 synthetic 15w50 the smoke is a medium brown, darker color. who knows. you really think it is the compression rings??

it's mostly a bad oil leak somewhere than anything
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Old 08-26-2003, 09:27 PM   #6 (permalink)
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Mine was leaking around there and it was the cam seals I think they are called.
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Old 08-26-2003, 09:32 PM   #7 (permalink)
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man, well i replaced the valve cover gasket, have a new oil filler cap, and it's not leaking from there now, and when i went out and test drove it the blow by hose blew off, so i put clamps on it and it's not that, but when it blew off, pheeww talk about blowing out some major oil. i just sooo hope it's not the front main seal. rebuilding talon motors is like kids play compared to what this car looks like. damn.
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Old 08-26-2003, 09:36 PM   #8 (permalink)
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I dont think it, just suggesting the possibility

The PCV needs to vent any pressure that enters the valve covers. On a good engine, this pressure should mostly consist of air that has been heated up and therefore expands.. so that the air pressure doesnt in turn raise oil pressure..

However, if pressure in the combustion chambers passes through the rings (as happens when they are worn).. then that air/fuel mix effectively enters the bottom end of the engine where all the oil is, and raises pressure throughout the engine... this places more demand on the PCV to vent the pressure...

Using oil is one way to diagnose worn rings... though its possible to have good oil rings and therefore little oil usage, but have very bad compression rings. One such car I worked on last week.. it was only a 4 cylinder engine, non turbo.. using virtually no oil.. but the amount of air coming out of the breather was amazing... under accelleration it was like a vaccum on reverse just blowing litres of air per second...

So just keep in mind that your PCV may be working fine..

Disconnect the PCV from the intake and plug up the hole it leaves in your intake system with some tape or something. Vent the PCV to atmosphere and bring the engine to operating temps... then give her some revs and see if there is a significant amount of air coming out of the breather. Ideally, there should be very little.

If there is a lot then its quite possible that excess pressure is being caused by bad compression rings

If there is little or no air, then do some tests to ensure the PCV is actually working properly. Im not sure of the design of the PCV on the 6G engine.. Toyota ones (denso, probably the same as whats on the 6G), which I am familiar with.. are just a very simple one way valve .. its just a device with a round steel ball in it. If air tries to suck through it, the ball moves and stops flow.. if air blows through it, it blows the ball to the side and allows flow...

What this means is you can simply take it off, try blowing through it each way (mmm.. oil taste good..) to see if it works. It would be good if someone could confirm the design of the valve though..!

-Tristan
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Old 08-27-2003, 02:16 PM   #9 (permalink)
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Quote:
Originally posted by Guy
Mine was leaking around there and it was the cam seals I think they are called.
True.
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Old 08-27-2003, 02:45 PM   #10 (permalink)
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Quote:
Originally posted by flupstar
I dont think it, just suggesting the possibility

The PCV needs to vent any pressure that enters the valve covers. On a good engine, this pressure should mostly consist of air that has been heated up and therefore expands.. so that the air pressure doesnt in turn raise oil pressure..

However, if pressure in the combustion chambers passes through the rings (as happens when they are worn).. then that air/fuel mix effectively enters the bottom end of the engine where all the oil is, and raises pressure throughout the engine... this places more demand on the PCV to vent the pressure...

Using oil is one way to diagnose worn rings... though its possible to have good oil rings and therefore little oil usage, but have very bad compression rings. One such car I worked on last week.. it was only a 4 cylinder engine, non turbo.. using virtually no oil.. but the amount of air coming out of the breather was amazing... under accelleration it was like a vaccum on reverse just blowing litres of air per second...

So just keep in mind that your PCV may be working fine..

Disconnect the PCV from the intake and plug up the hole it leaves in your intake system with some tape or something. Vent the PCV to atmosphere and bring the engine to operating temps... then give her some revs and see if there is a significant amount of air coming out of the breather. Ideally, there should be very little.

If there is a lot then its quite possible that excess pressure is being caused by bad compression rings

If there is little or no air, then do some tests to ensure the PCV is actually working properly. Im not sure of the design of the PCV on the 6G engine.. Toyota ones (denso, probably the same as whats on the 6G), which I am familiar with.. are just a very simple one way valve .. its just a device with a round steel ball in it. If air tries to suck through it, the ball moves and stops flow.. if air blows through it, it blows the ball to the side and allows flow...

What this means is you can simply take it off, try blowing through it each way (mmm.. oil taste good..) to see if it works. It would be good if someone could confirm the design of the valve though..!

-Tristan
Oh but don't forget when under boost you'll build some pressure in the bottom end. This is why we see leaking from the oil filler cap and/or the dipstick blowing out. A faulty PCV can contribute to this but you can see it even with a new one. The best that I've seen to fix this are Krank-Vents. They work miracles.
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