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Turtle n Peeps wrote:
That's all well and good except the 8.1 (the OP's engine) does not have a PCV valve. :S
Turtle,
Yeah. It often appears that may be so. Yet the older
standard 454 PCV system is described in my Helms 1974 GM truck manual. Why would GM remove it? One of the benefits of PCV systems is that they help prevent gasket leaks by equalizing pressure between atmospheric and internal engine crankcase pressure. A faulty standard PVC results in not only excess oil consumption, but the pressure build-up encourages oil leaks as well. So how has this valuable device seemingly been eliminated?
Sport45 wrote:
How does the 8.1 deal with crankcase vapors? I can't imagine it has an old-school vent on the oil fill cap.
My old Fords must not have had that fancy "best design" PCV system. Or maybe they were run way past their intended service life. I can remember pouring oil out of the air filter housing when the PCV valve stuck shut and the crankcase ventilation stopped. Back then the breather hose from the oil fill cap just ran to a small fiber air filter pinned to the side of the breather.
I wondered too, what do we propose is done with blowby pressure created in the crankcase in this year 2001 3/4 ton truck? Are non EPA regulated trucks still dumping exhaust, oil vapor and unburned fuel into the atmosphere and on the ground? Curious minds want to know. ;)
I finally found a hint online in
this pdf. This states in part:
"The Vortec 8.1L is the debut of a new, highly-refined big block V8. Introduced
in Chevrolet Silverado and GMC Sierra heavy-duty pickups and Medium Duty trucks, the Vortec 8.1L is the
legendary GM big block for a new millennium, with 33 percent increase in expected useful life, and horsepower &
torque that surpass the competition. The following aspects are new or have been changed: a revised engine
block; new pistons with 5-millimeter top land; improved firing order; internally balanced crankshaft;
replicated-port cylinder heads; low-noise & high-durability valve train; cast stainless steel exhaust manifolds;
internal positive crankcase ventilation (PCV); modified sequential port fuel injection; electronic throttle control;
coil-near-plug ignition; more durable water pump; improved cooling system with coolant loss protection;
serpentine belt drive; oil-life monitor; oil-level sensors; raised rocker-cover rails; thermoplastic sight shield; cast
aluminum oil pan; improved seals; and all metric fasteners. Before the Vortec 8.1L, Electronic Throttle Control
(ETC) was largely reserved for premium passenger car engines. Because there is no mechanical link between the
accelerator pedal and the throttle, a potentiometer at the pedal measures pedal angle and sends a signal to the
Powertrain Control Module (PCM), which then directs an electric motor to open the throttle appropriately."So I don't know where the PCV is on the OP's engine. But if it malfunctions as do all the external ones eventually do,
or is absent altogether, the engine as it wears, should logically develop leaks and a thirst for oil consumption as I described.
Wes
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