Excessive Oil consumption, 1995 Bonneville Vin K 3.8
Replaced lower intake gaskets, while doing so I observed puddles of oil on top of lower intake manifold. While installing 2 bolts under plenum I added Permatex #2, new upper intake gaskets and new plenum. Vehicle Still uses a quart after 250 miles. PCV is suspect, since the engine is a 99 but I have re installed all the 95 components. PCV is in a compartment of the plastic plenum, but no external vacuum line is connected... wondering if there should be,, how does PCV vent without external Vacuum line?
Re: Excessive Oil consumption, 1995 Bonneville Vin K 3.8
The PCV valve gets it's vacuum from the plenum itself. Some 3.8L have different types of connections on the top of the valve (electrical or mechanical), but none have a vacuum line on them.
If you replaced the lower intake gaskets, it is very likely they crushed around the intake bolts. This will cause oil to leak into the intake and pool in the recesses of the lower intake. You are also likely to be leaking anti-freeze.
This is a very common problem with OEM gaskets. After market gaskets made by Fel-Pro have metal rings in them specially to stop this problem. They are available at NAPA and other stores.
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Dear Sir, Here is the oil leaking Problem Identifying Technique
Engine oil leaks from the valve cover gasket are common.
The intake manifold plenum gasket may leak and cause increased oil consumption/burning and a spark knock during acceleration; the gasket should be replaced.
External oil leaks from valve cover gaskets, intake gaskets (front or rear), and the rear crankshaft (rear main) seal area are common. The rear main seal is an unlikely source. Normally, the bearing cap mating surfaces (as well as the sealing surface between the oil pan and bearing cap) are the source for the leaks.
If the oil filter casing shows signs of distortion from excessive oil pressure, theoil pump should be replaced.
Often misdiagnosed as a leaking oil filter gasket, the oil filter adapter can seep from between the adapter and engine block.
Carbon buildup on the top of the piston is common. As the buildup increases with mileage and over time, symptoms may vary from light ticking, to ticking/hammering, to hammering/knocking noises. Fuel injector cleaner often solves the problem.
Believe it or not, it is normal for these engines to use about a quart every 2000 even when they are essentially new. Note that I said, "use", not "burn". The combination of higher compression and operating temperatures causes oil to pass through the engine. You might notice your tail pipes have a good coating on the inside. I managed to slow the process by converting to Mobil 1 0W40. I get much better performance and I only use a quart every 3500-4000.
if no puddles or no keaks you can see, then its probably your head gaskets, or the intake gaskets leaking. look all around intake to see if you see any leaks. if you do its your intake gaskets. how does the coolant look! on my car when the intake gasket was leaking, it made the coolant look milky and a chocolate type mixture. so check it out first, the intake gasket. Coolant may flow through the gasket to the inside of the engine and mix with the oil. Pull the oil dipstick out and look at it. Oil mixed with coolant will have a thick consistency. Examine the oil filter cap for any rusty-looking residue. good-luck.
The PCV valve does not control the oil situation, it just keeps the pans and valve covers from blowing off during a backfire. Excessive Oil in the breather is a result of excessive crankcase pressures, usually due to a worn engine, specifically rings.
SOME oil is normal, especially if you are loaded heavily and hard on the throttle.
There is a tester that measures crankcase pressures, but usually some other manifestation shows, like excessive oil consumption.
the PCV system draws crankcase fumes into the intake at idle and lower throttle situations. air going into the crankcase is filtered by the small PCV filter, where the oil shows up....
At highter throttle and lower intake manifold pressures, the system reverses, the PCV valve closes, and the fumes exit the crankcase VIA the breather filter. All of this is normal.
It costs tons less to periodically clean or replace the PCV filter.
It's not suprising that the engine stalled after getting hot considering you had run the engine out of oil as indicated by oil pressure light coming on and needing two quarts to refill it. Now that the oil is replaced, you could keep driving, but it would be wise to investigate why it had got so low on oil in the first place. Refer explanation below. You should check the oil level weekly to ensure it is at the correct level and top up if necessary. For that year vehicle, oil and filter changes should be around the 3,000 mile / 5,000 Km mark. It sounds like the engine could be using excessive oil by either leaking out or being burnt in the cylinders.. If there is a major leak then there will be oil puddles under the engine after sitting for a while. Excessive oil burning in the cylinders is indicated by grey oil smoke from the exhaust when driving. If engine has oil and grime all over the best way to find the leaks is to get the engine pressure cleaned and then observe where the oil leaks are. The most usual places for older vehicles are the sump and valve cover gaskets followed by crankshaft seals. Oil leaks can also come from a loose oil filter or a faulty warning light pressure switch. If exhaust smoke is excessive then it would indicate worn piston rings and / or valve guides and seals.
According to GM 1 quart per 1,500 miles is an acceptable oil consumption tolerance. 1 quart in 3k isn't bad.
I've had several gm 3.1 and 3.4 liters that have had there oil consumption issues remedied after the lower intake gaskets where replaced due to coolant leaking.
There are a couple of common problems that can cause oil consumption. Valve seals, bad rings, and PCV valves.
Valves seals would require a valve job which would requirethe removal of the heads. Rings would require a motor rebuild. Both of these are expensive options and oil is still pretty cheap.
Replacing the PCV valve might help. On the 3.8 it will be under the MAP sensor on the passenger side of the intake plenum.
As for as the intake gaskets, its a possibility but I don't have any hard evidence this could be the problem on a 3.8. Eventually the gaskets will start to leak oil. If you decide to replace them at that point I guess you will find out. I wouldn't do it on a hunch, its not a cheap repair.
Anything over 1 quart in 1000 miles might be considered excessive. It probably is not gaskets unless there is a leak. If there is a leak there might be a puddle of oil on the ground where you park it. If there is a puddle or drips of oil look at valve cover gaskets, oil pan gaskets, crankshaft seals , etc.
It could be burning and you don't notice. Remove air filter box assembly from top of intake manifold. Hold throttle wide open (engine off) and look through throttle body (flashlight may be required) and see if oil is puddled up inside manifold. If so then the intake manifold will need to be removed so the lower pan gasket can be replaced.