LT1 went to the shop and .....
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LT1 went to the shop and .....
So my buddy here at work has a 93 T/A with an LT1. Had some broken exhaust mani bolts that needed to be tapped out and he felt he would leave it to the "pro's".. well he just got it back and it was running horribly bad like it was missing horribly. i could hear a super large vac leak and noticed this guy had actually cut his hard EGR pipe and bandaged it with heater hose that appears to immediately burned through. So i fixed that with some steel braded hydro line good for 700 degrees on the rubber side and 1300 on the braid side (inside) resolved. But while i was in there i noticed he had a new hose coming from the TB to the p/s valve cover and a PCV valve in there. stumped me simply because when i owned an LT1 i could have swore the pcv was on the D/S side of the intake mani and the positive flow actually went to a simple vent in the P/S valve cover. he is having an issue with oil coming out of the dipstick. so i took that pcv off the P/S and gutted it and stuck it back in. Did i do the right thing?
#2
Too much flow without the internal valving. That PCV controls flow by vacuum and at low rpm/high vacuum it reduces flow since there should be less blowby and saves idle vacuum. Once RPM increase the vacuum signal is reduced and the PCV is open internally to handle the greater blowby past the rings. It is also a check valve in the opposite direction for whatever reason.
With the PCV gutted it will be like a major vacuum leak as if the hose was connected by itself. But if he was having oil come out the dipstick means that hose is not connected to the intake vacuum or a hole in the valve cover. This is pressurizing the crankcase and will blow out all the engine oil seals.
Get the correct PCV connected to a vlv cover hole that is open and the other end to the intake.
cardo
With the PCV gutted it will be like a major vacuum leak as if the hose was connected by itself. But if he was having oil come out the dipstick means that hose is not connected to the intake vacuum or a hole in the valve cover. This is pressurizing the crankcase and will blow out all the engine oil seals.
Get the correct PCV connected to a vlv cover hole that is open and the other end to the intake.
cardo
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Too much flow without the internal valving. That PCV controls flow by vacuum and at low rpm/high vacuum it reduces flow since there should be less blowby and saves idle vacuum. Once RPM increase the vacuum signal is reduced and the PCV is open internally to handle the greater blowby past the rings. It is also a check valve in the opposite direction for whatever reason.
With the PCV gutted it will be like a major vacuum leak as if the hose was connected by itself. But if he was having oil come out the dipstick means that hose is not connected to the intake vacuum or a hole in the valve cover. This is pressurizing the crankcase and will blow out all the engine oil seals.
Get the correct PCV connected to a vlv cover hole that is open and the other end to the intake.
cardo
With the PCV gutted it will be like a major vacuum leak as if the hose was connected by itself. But if he was having oil come out the dipstick means that hose is not connected to the intake vacuum or a hole in the valve cover. This is pressurizing the crankcase and will blow out all the engine oil seals.
Get the correct PCV connected to a vlv cover hole that is open and the other end to the intake.
cardo
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ok got my answer, there is no "valve" on the passenger valve cover, it is WOT vac only so it was supposed to just have a open elbow in there but the "mechanic" that worked on his car must have broken it off so he just stuck a pcv valve in there to replace it which made sense all the way up to its not supposed to have internals. if anyone else has any more input on the subject i would love to learn.
Last edited by LIQUIDZ28; 12-26-2013 at 04:51 PM.
#6
That drawing shows the PCV connects from the intake to another port on the intake below on the same drivers side. So that tells me the intake has a passage to the lifter valley where it receives the blowby gasses.
That hose on the valve cover that is blowing at u is where the blowby crankcase gasses are trying to get out. As long as u have the PCV installed in the correct direction no reason why u cant use that for a PCV port - but the other end has to go to the intake vacuum port.
cardo
That hose on the valve cover that is blowing at u is where the blowby crankcase gasses are trying to get out. As long as u have the PCV installed in the correct direction no reason why u cant use that for a PCV port - but the other end has to go to the intake vacuum port.
cardo
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I would be hard pressed to have anyone even check my oil. IMHO if you own a sports car, you need to know her like the back of your hand. This one just stumped me as there was 2 pcv valves. Just got off the phone with the guy i sold my 97 z28 to had him check the p/s valve cover and sure as sh*t there is no pcv there, just an open elbow. I really would have rather gotten the answer from here as i diddnt want to bug the guy but wanted to have it handled before he drives home in an hour.
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The 93's only have one PCV Valve, which is on the drivers side of the manifold in a big rubber grommet, and a 180* tube that connects to a port right next to the PCV itself.
The passenger valve cover to throttle body is a fresh air hose. There should be NOTHING in that line.
The passenger valve cover to throttle body is a fresh air hose. There should be NOTHING in that line.
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The 93's only have one PCV Valve, which is on the drivers side of the manifold in a big rubber grommet, and a 180* tube that connects to a port right next to the PCV itself.
The passenger valve cover to throttle body is a fresh air hose. There should be NOTHING in that line.
The passenger valve cover to throttle body is a fresh air hose. There should be NOTHING in that line.
#11
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So my buddy here at work has a 93 T/A with an LT1. Had some broken exhaust mani bolts that needed to be tapped out and he felt he would leave it to the "pro's".. well he just got it back and it was running horribly bad like it was missing horribly. i could hear a super large vac leak and noticed this guy had actually cut his hard EGR pipe and bandaged it with heater hose that appears to immediately burned through. So i fixed that with some steel braded hydro line good for 700 degrees on the rubber side and 1300 on the braid side (inside) resolved. But while i was in there i noticed he had a new hose coming from the TB to the p/s valve cover and a PCV valve in there. stumped me simply because when i owned an LT1 i could have swore the pcv was on the D/S side of the intake mani and the positive flow actually went to a simple vent in the P/S valve cover. he is having an issue with oil coming out of the dipstick. so i took that pcv off the P/S and gutted it and stuck it back in. Did i do the right thing?
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Check the routing of the spark plug wires. The hose from the passenger VC is a breather tube, which is to remain neutral. When the car is under vacuum, it draws it's filtered/metered air through that hose, and when it's not in vacuum, blow-by is supposed to channel through that hose into the intake. Gutting the valve was the right thing to do, but if you want to be thorough, locate a grommet and fitting for the correct breather tube.
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If anything it's filtered air being introduced inside the engine. The PCV valve may have stopped up the normal blow by causing excessive crankcase pressure which could mean a dipstick shooting up. Just a guess.
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