Boost leak test

[sharky559]

Okay so I did a boost test on my 2g. Im getting a leak at the dip stick hole and at the bov. The part that has me confused is that, there was pressure building inside the cylinder head. No air was coming out of the PCV but air was coming out of the breather,If you cover the hole with your finger it would build pressure. need help please

 

[sharky559]

It doesnt pop out. I could hear a lil air come out. it looks like air is passing through the rings, since i did gap the ring to run nos.

 

[shockracer]

A little blow by is ok, the BOV leaking is normal as well.

If the blow by bothers you that much do a leak down test.

 

[LiquidX]

Zip-tieing the dip stick is only covering up a problem.
http://www.dsmtuners.com/forums/articles-engine-fuel/366890-4g63t-pcv-system.html

When you do the boost leak test, ensure that your intake valves are closed.
http://www.dsmtuners.com/forums/art...-boost-leak-test-how-boostpro-net-tester.html

If you pressurize at the turbo inlet, then yes, you will get air into the block as it will enter through the turbo seals which could be the reason your dipstick pops out during testing. As for the BOV either it's adjusted improperly or you have a leaking diaphragm.

Think about it for a second, if you pressurize the intake system, the IC pipe will be at say 20psi which is pushing up on the BOV plunger. When the air enters the intake manifold, it will go through the vacuum line that attached to the top part of the BOV, that is effectively adding the same 20psi of pressure to the top part of the plunger pushing it down. The pressure is equal on both halves and will keep the BOV closed assuming the BOV is functioning and adjusted properly.

If the diaphragm is leaking then the top half of the pressure is leaking out making the lower half a higher psi than the top which will push open the plunger. Same way it works when you let off the throttle, pressure in the bottom half, vacuum in the top half.

A BOV should not leak at idle, just FYI.

 

[sharky559]

I think I found the problem, the PCV valve took a crap. I blow(both ends) in it and it comes out the other side. I'm going to buy a new one and see what happends. also i did some reading on the 4G3T PCV system last night and it looks like i should be gettinga catch can.

 

[LiquidX]

Make sure you get an OEM unit and for extra insurance, U.S. Plastic Corp. you'll want the 3/8" Kynar valve.

 

[MrKelly]

If its a oem plastic bov they leak when they are new. My tial leaked until I changed the spring. You should def get a catch can, keeps intake track clean and oil free, get one with a breather though. If you make sure your intake valves are closed and your dipstick still pops up when you test it, its the pcv. Take it off and pressure test it by it's self, I'm sure somebody posted the pressure it's supposed to hold on here somewhere.

 

[ILL122]

If its a oem plastic bov they leak when they are new. My tial leaked until I changed the spring. You should def get a catch can, keeps intake track clean and oil free, get one with a breather though. If you make sure your intake valves are closed and your dipstick still pops up when you test it, its the pcv. Take it off and pressure test it by it's self, I'm sure somebody posted the pressure it's supposed to hold on here somewhere.

Im sure he was talking about an OEM pcv valve.

 

[MrKelly]

I don't even run them, just 2 -8 an braided lines to a vented catch can

 

[bryanwheat]

I don't even run them, just 2 -8 an braided lines to a vented catch can

You need vacuum on the crank case to keep it vented well. If not than you will have excess moisture and fuel vapors in the crank case which can dilute the oil.

 

[MrKelly]

Yea, I've heard of that but never personally had an issue, I don't drive it everyday and I change the oil every couple months, usually clean when I change since there's low milage. Seems like the bigger set up non daily driver cars don't run them but people that cycle the engine on and off multiple times a day need them. Not disagreeing but how does a valve that relieves pressure create vacuum? Always thought it was the other way around, when the pressure backs up it causes moisture to condensate within the case? Once you hook a catch can up to the valve it doesn't have any negative pull from the intake manifold or the intake track anymore. I thought the theory behind the PVC was to keep a certain amount of pressure in the case, almost like a pressure regulator.

 

[bryanwheat]

It is a 1 way valve. It allows vacuum to be pulled thru to the intake manifold when the throttle body is closed. This pulls all the vapors into the combustion chamber and out the exhaust. When you go into boost the valve closes so that there is no pressure in the case.

 

[MrKelly]

Could see some sense in that but what about when you run a catch can?

 

[bryanwheat]

When you run a catch can, you still need vacuum present in the crank case. Most do it with a check valve. I prefer to just leave the pcv in place than run the 1 tune from the valve cover to the intake to the catch can, than a line from the catch can to the intake pipe. The catch can is just there to catch the oil in the line from the intake to the valve cover to keep oil out of the turbo, intake pipe and intercooler piping.