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Why is there vacuum at the oil filler on my 1999 3800 V6?

It takes in air and releases continuing fuel and air through the exhaust. Let me clarify.

Simple Ways to tell if your GM 3 8 Series II Intake Gaskets are Leaking

To drive the car, your car engine needs appropriate air that means oxygen and fuel combination on its cylinder. It makes explosions on the cylinders. To supply this oxygen is the task of the intake manifold. It distributes the same amount of air to each cylinder.

Generally, a leaky intake manifold gasket will make various symptoms that can alert you at the initial time.

Buick LeSabre P0300: Engine Misfire Detected

So, you need to know the intake manifold gasket leak symptoms clearly. This is made of metal, rubber or plastic and sometimes with the combination of these elements. It fills the small gap between the engine and intake manifold. If this gasket is failed then excessive air enters into the cylinders. It causes engine overheating and drivability problems. One of the recognizable symptoms of bad intake manifold gasket is coolant leaks. Intake manifold gasket works as a seal for the coolant of your car engine.

Generally, when this seals were damaged, then the coolant will flow out over the seal. Leaks allow the coolant and motor oil to mix together.

gm 3800 vacuum leak

External leaks are very easy to find. But if there is an internal leak which causes the coolant to flow into the combustion chamber is quite tough to spot them. But you need to ensure, is it coolant leak or not? After confirming the coolant leak, you need to find the location of leaking.Common Problems with the Engine: An intermittent chuggle or hesitation that can be felt during light acceleration or while cruising at highway speeds with no Check Engine light or no fault codes set may be caused by intermittent operation of the automatic transmission torque converter clutch TCC.

Buick 3800 Engine Problem Diagnostics

The fix for this problem is to replace the TPS sensor. The OEM intake manifold gasket tends to deteriorate after 60, or so miles in the area that seals the cylinder head coolant passage to the manifold.

The fix is to replace the intake manifold gaskets. Intermittent Hesitation While Accelerating or While Cruising Intermittent Misfire While Driving An intermittent misfire that occurs while driving may be caused by a weak coil or worn spark plugs. The distributorless ignition system on the V6 is a waste spark system with three ignition coils.

Each pair of cylinders shares a common ignition coil. This reduces the total number of coils needed. When each coil discharges its high voltage output, it fires two spark plugs simultaneously: one when cylinder is on its compression stroke, and the other when the cylinder is on its exhaust stroke. Only the plug that fires during its compression stroke produces power. Even so, both spark plugs experience roughly twice the electrode wear that spark plugs in other types of ignition systems undergo because the fire every engine revolution rather than every other engine revolution.

Remove and inspect the spark plugs. Replace the spark plugs if any are found to be fouled or worn. The spark plugs should be gapped to. If the spark plugs appear to be okay, inspect the ignition wires. High mileage wires those with overmiles on them can develop increased resistance that may cause the engine to misfire.

Replace any wires that are cracked, fit loosely or are damaged. The Check Engine light should be on, and there should be one or more misfire codes for the cylinders that are misfiring.

The last digit on a misfire code indicates the cylinder number. A code P, for example, would tell you cylinder 2 is misfiring. Chances are the misfire is due to a weak ignition coil. The three ignition coils on the engine fire cylinders 6 and 3, 2 and 5, and 1 and 4.

If you find misfire codes for any of these paired cylinders, you can be sure the problem is a bad ignition coil and not something else such as lean misfire caused by a bad fuel injector, vacuum leak or EGR leak, or compression misfire due to leaky or sticky valves. Ignition coils can be replaced separately on the ignition module. But if one coil is bad, it may be a good idea to replace all three on a high mileage engine to prevent similar problems down the road. The crank sensor contains two hall effect sensors that sends two signals to the engine computer.Home Articles Idling High How to Fix High Idle Step by step automotive repair guide on how to troubleshoot and fix an engine that is idling high fast or low slow.

Note: The engine idle speed is controlled by the computer and is NOT adjustable. The troubleshooting procedure for high and low idle conditions are similar, which are included in the following:. Step 1 - If the check engine or service engine light soon has illuminated retrieving the diagnostic trouble codes could lead you in the right direction of what the problem is, or is related too.

Check Engine Light Step 2 - The idle air control motor valve is responsible for controlling the engine idle speed, if this part fails or becomes weak the engine idle speed could become erratic, additionally, this condition may or may not trigger the MIL check engine, service engine soon light.

Because of the nature of this valve large air volume processed it should be serviced when a tune up is performed to remove "coking" which will hinder the valve's performance. To perform a rough check of the idle air control, remove the valve while reconnecting the wiring harness. Idle Air Control Valve Off Engine Step 3 - Engine vacuum is a sealed system and must hold a specific amount to maintain proper idle conditions, inspect the engine vacuum hoses and intake gaskets.

Engine Intake Vacuum Leak Step 4 - The air intake boot or tube is used to deliver air to the intake system of the engine. If this tube becomes loose or broken it can leak un-metered air into the engine effectively causing an unbalance via the mass air flow MAF sensor in the computer system which can produce fast or slow idle. Removing Air Intake Boot Step 5 - A throttle bore is used to regulate the volume of air flow the engine consumes. Controlled either by computer or by manual foot pedal this device must be clean and free from coking build up light tar substance.

Throttle Bore Service Step 6 - The crankcase ventilation system or PCV valve of an engine is used to scavenge vapors from inside the engine while running, if this system malfunctions erratic idle conditions may result. Crankcase Ventilation Step 7 - Engine timing, both ignition and camshaft orientation can effect the engine idle speed.

gm 3800 vacuum leak

When this condition exists the computer is rendered unbalanced and will not react correctly. These items must be checked and corrected before normal engine operation will resume. Step 8 - The mass air flow sensor uses a hot wire that changes in resistance as engine intake air is passed by it.

The computer uses this information to make adjustments to the operating system. When this wire becomes contaminated which naturally occurs during usage, the sensor must be removed and cleaned.

Intermittent sensor failure or shorting can cause the computer to act strange with unusual side effects, these problems are particularly tough to diagnose. The computer program is designed to trigger a MIL check engine - service engine soon only when a long term failure has occurred. In these cases there are many approaches that can used, the most professional method involves using a computer scanner that will monitor and record the data stream which then can be monitored for unusual patterns in various sensors or connections.

An alternative method of troubleshooting involves a one at a time, replace all critical sensors approach which can reveal the failed sensor i. Home Articles Idling High. How to Fix High Idle. Step by step automotive repair guide on how to troubleshoot and fix an engine that is idling high fast or low slow. The troubleshooting procedure for high and low idle conditions are similar, which are included in the following: Difficulty Scale: 4 of 10 Step 1 - If the check engine or service engine light soon has illuminated retrieving the diagnostic trouble codes could lead you in the right direction of what the problem is, or is related too.

Check Engine Light. Engine Intake Vacuum Leak. Removing Air Intake Boot. Throttle Bore Service. Crankcase Ventilation. Mass Air Flow Service. Ask a Car Question.

It's Free!Air leaking ,into, your car—not out of it—can be a problem. A year ago, with the suggestion of this community, I cleaned my throttle body has. This project would not have been possible without the tireless efforts of many people.

Notice the datastream is showing ECM internal voltage at 4. If there's a leak present, engine vacuum will draw the fluid in; once in the engine, the fluid will act as a supplemental fuel, causing a momentary rise in engine rpm. This has only started within the last few days. That can get dirty or stick and cause idle issues. The Buick Worth mentioning for the sake of differentiation is the 60 Degree GMintroduced in I have checked for vacuum leaks three different ways.

Just hook up a vacuum pump to the EGR valve while the engine is off and apply anywhere from 7 to 20 inches of vacuum and see if the EGR valve holds steady. The OEM intake manifold gasket tends to deteriorate after 60, or so miles in the area that seals the cylinder head coolant passage to the manifold. Honeywell Friction Materials carries a full line of drums and rotors that are engineered to OE specifications and manufactured worldwide in ISO or TS certified.

The buick v6 is a fairly reliable engine but coolant leaks on the series ii engines with the plastic intake manifold have been a problem. PCV valve failed caused the engine to suck air and made engine shack. See full list on obd-codes. Physically check all vacuum hoses for dry rot, tears, and holes. Transmission problems have been identified for every model produced by Buick, though some years have fared better than others.

Coolant can leak from the reservoir or from the hoses, in Centurys with the 3. A vacuum leak would be from the gaskets between the manifold and the head. The video above shows you where the coolant reservoir, hoses and connections on your Century Custom are located and the steps needed to fix minor leaks. Just scrape clean and install new gaskets.

You pay for the quality. Learn more about used Buick LeSabre vehicles. We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

April 25th, - Buick century thermostat location further buick century brake line diagram in addition pontiac series 2 vacuum diagram furthermore t 97 buick riviera leaks coolant along with repairguidecontent along with Oct 18, Chevrolet Impala. Oil leak, replaced engine rear main seal and clutch due to effect of oil on it : mi: Oil cooler seals leaking, replaced seals.

Diagnosis of oil leaks on a GM V6 These handsome aluminum Delco V-6 Intake gaskets put an end to vacuum and fluid leaks the mid 's series 2 and 3 engines were known for. Once again, if you don't do this the new one might leak. Inspect and clean the throttle body.

Speed-density systems are extremely sensitive to vacuum leaks. Oil was changed.The Buick V6 is a fairly reliable engine, but coolant leaks on the Series II engines with the plastic intake manifold have been a problem. The OEM intake manifold gasket tends to deteriorate after 60, or so miles in the area that seals the cylinder head coolant passage to the manifold. The fix is to replace the intake manifold gaskets. An intermittent chuggle or hesitation that can be felt during light acceleration or while cruising at highway speeds with no Check Engine light or no fault codes set may be caused by intermittent operation of the automatic transmission torque converter clutch TCC.

The problem is not the torque converter clutch or clutch solenoid, but a faulty input to the powertrain control module computer from the engine's throttle position TPS sensor. The fix for this problem is to replace the TPS sensor. There are a variety of possible causes for a no start, but one of the most common with the engine is a bad crankshaft position CKP sensor or a bad ignition control module ICM. The crank sensor contains two hall effect sensors that sends two signals to the engine computer.

A problem with the sensor or the wiring connection between the sensor and computer can prevent the computer from receiving a cranking signal. Without this signal, it can't start the engine. The crank sensor has four circuits: a volt reference circuit, a low voltage reference circuit, and two signal output circuits. NOTE: If the crank sensor is bad and needs to be replaced, a special relearn procedure must be performed after the new sensor has been installed using a GM scan tool or an aftermarket scan tool with similar software.

This step is necessary so the engine computer can correctly recognize the sensor's signals. Diagnosing the crank sensor requires looking up the engine wiring diagram for your vehicle, then testing the voltages for the various crank sensor and ignition module circuits to find the fault.

With the key on, you should find about 4 to 8 volts between each of the crank sensors two output circuits and the low voltage reference circuit. If the crank sensor tests bad, it needs to be replaced. The sensor is located on the front of the engine under a cover behind the crankshaft pulley.

If the crank sensor tests good, the problem is likely the ignition control module, a fault in the ignition wiring harness, or possibly a fault in the engine computer. An intermittent misfire that occurs while driving may be caused by a weak coil or worn spark plugs.

The distributorless ignition system on the V6 is a waste spark system with three ignition coils. Each pair of cylinders shares a common ignition coil. Cylinders that are opposite one another in the engine's firing order are paired so their spark plugs share the same coil.

This reduces the total number of coils needed. When each coil discharges its high voltage output, it fires two spark plugs simultaneously: one when cylinder is on its compression stroke, and the other when the cylinder is on its exhaust stroke.

They call it a "waste spark" system because the plug that fires on the exhaust stroke does nothing. Only the plug that fires during its compression stroke produces power. Even so, both spark plugs experience roughly twice the electrode wear that spark plugs in other types of ignition systems undergo because the fire every engine revolution rather than every other engine revolution.

Remove and inspect the spark plugs. Replace the spark plugs if any are found to be fouled or worn.

gm 3800 vacuum leak

The spark plugs should be gapped to. If the spark plugs appear to be okay, inspect the ignition wires. High mileage wires those with overmiles on them can develop increased resistance that may cause the engine to misfire. Replace any wires that are cracked, fit loosely or are damaged. If the plugs and wires are okay or you've replaced themand the engine still experiences misfires, use a scan tool to check for misfire codes.

The Check Engine light should be on, and there should be one or more misfire codes for the cylinders that are misfiring. The last digit on a misfire code indicates the cylinder number.My Lacrosse 3. I have to add a splash probably under a half cup just once every couple of weeks to keep the recovery tank on full. A year ago, with the suggestion of this community, I cleaned my throttle body has coolant running through it.

A month or two ago, I tore back into the throttle body, to replace the gasket in hopes that it was the culprit. It was in bad shape and melted. I replaced it with a new Fel-Pro gasket and put it back together. I also changed the coolant, replaced the reservoir, and replaced the radiator cap. These are apparently a common problem. Throttle body mounting gasket again - torque specs are 89 in-lbs.

I bought a torque wrench that had in-lbs but it was really just a foot-lbs one that had markings for in-lbs. So I just snugged the bolts up. You might at least see signs of crusty dried coolant, which would point you to the leak. Might be something as simple as a crusty water pump, hose, radiator, etc. Perhaps the leak is more obvious with the engine running. The plastic intakes on these things are notorious for melting where the EGR passage goes through the upper intake.

I own 3 GM cars with that 3. These engines are fairly bullet-proof. My vote is for the coolant elbows 2. Take a look with a flashlight. You might want to try stuffing a little piece of paper towel just below the forward elbow where it leaves the head. See if gets damp with coolant. Neither replacement is a major operation. It can be done with care and hand tools in the driveway. It is definitely tight in there. If I recall a fluid leak from there can drip down and land on the edge of the head gasket itself.

I have a cooling system pressure tester Stant. It goes on the radiator neck. That device allows one to pressurize the cooling system, cold and have a look. How about any drips on the plastic shield below the drive-belt serpentine belt that could indicate a water pump leak.Engine runs fine A pulley bearing noise at the front of the engine goes away when oil filler cap is removed Upper intake manifold was just replaced.

John answered 7 years ago. PCV valve should keep the crankcase pressure pretty neutral. Are you certain its a vacuum, sometimes the crank feels like it has vacuum but its actually pressure. If that was the case then removing the oil cap would cause the vehicle to run super rough.

Anthony answered 7 years ago. I would think that if the PCV valve is stuck open, you would get a constant vacuum in the crank case. It's definitely vacuum at the oil filler. The PVC appears to be fine. The engine runs well overall so I"m holding out a hope that the heads are intact at least though the lower intake is surely a serious and expensive bit of work.

Thanks John. The PCV valve tube shouldn't be under vacuum unless the air filter is severely clogged. Positive crankcase ventilation not negative.

The PCV tube goes to the air cleaner tube or the top of the throttle body where there is only venturi vacuum and that only affects liquids and it only affects liquids when there is a massive flow of air.

If the air filter was clogged enough to cause the PCV to have a vacuum then it would run horribly. Any way it goes I don't see how removing an oil filler cap causes a bearing noise to go away.

I know fords make an obnoxious whistling when the PCV filter gets clogged. Gotta clean it out with Carb cleaner. Ineedapepsi answered 7 years ago. I have had this problem as well on my Grand Prix.