try this question here..
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
Pasta, some info from another forum:
"...As it was explained to me, the oil is from compression/back pressure (ie-High RPM or letting off or down shifting at high speed). It pushes oil into the vent tube which, in turn is drawn by vacuum into the TB. On my 96, it deformed the rubber gasket seal under the top plate."
"Should be no oil there if PCV system is working correctly.
Unless a LT1 is different from a L98 ,that is a SUPPLY port for the PCV system;
Air goes in pass side cover, out PCV valve in drv side cover ( or in the case of a LT1, drv side of intake , ) to intake.
There is no vac on that port, but vac on the lower one for charcoal canister purge."
"vetteoz is correct, the plastic line to the throttle body is the fresh air supply line to the crankcase on an LT1, airflow is from the throttle body to the valve cover. The PCV valve is on the other side of the intake manifold under the fuel rail cover, consult your FSM section C13, book two for verification.
Oil in the top of the throttle body indicates problems with the PCV system or excessive blow-by."
Source: http://www.corvetteactioncenter.com/...ttle-body.html
"...As it was explained to me, the oil is from compression/back pressure (ie-High RPM or letting off or down shifting at high speed). It pushes oil into the vent tube which, in turn is drawn by vacuum into the TB. On my 96, it deformed the rubber gasket seal under the top plate."
"Should be no oil there if PCV system is working correctly.
Unless a LT1 is different from a L98 ,that is a SUPPLY port for the PCV system;
Air goes in pass side cover, out PCV valve in drv side cover ( or in the case of a LT1, drv side of intake , ) to intake.
There is no vac on that port, but vac on the lower one for charcoal canister purge."
"vetteoz is correct, the plastic line to the throttle body is the fresh air supply line to the crankcase on an LT1, airflow is from the throttle body to the valve cover. The PCV valve is on the other side of the intake manifold under the fuel rail cover, consult your FSM section C13, book two for verification.
Oil in the top of the throttle body indicates problems with the PCV system or excessive blow-by."
Source: http://www.corvetteactioncenter.com/...ttle-body.html
Last edited by don hall; Apr 4, 2014 at 12:40 PM.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
"Should be no oil there if PCV system is working correctly.
Air goes in pass side cover, out PCV valve in drv side cover ( or in the case of a LT1, drv side of intake , ) to intake.
Oil in the top of the throttle body indicates problems with the PCV system or excessive blow-by."
Air goes in pass side cover, out PCV valve in drv side cover ( or in the case of a LT1, drv side of intake , ) to intake.
Oil in the top of the throttle body indicates problems with the PCV system or excessive blow-by."
