I have a 2001 bonneville that is leaking coolant externally from the intake. I have heard there are two intakes an upper and lower. Witch one would be the problem and is this fairly common in this year of car?

If it has the 3800 engine, usually the issue with this engine is at some time, the upper intake manifold (plenum) developed an internal coolant leak, from the plastic housing just under the throttle body, from the EGR tube that flows in to upper plenum. This causes the coolant to seep into the lower intake manifold ports and into the engine cylinder, on top of the piston, and when the engine turns over, sometimes this coolant causes this concern. If at any time you started your engine, and it stopped turning (cranking) over for a split second and then cranked over to start, this could cause the connecting rod to bend slightly causing the internal engine knock. Was your coolant/antifreeze ever low?? Is your engine oil have a milky color?

Time for Intake Gaskets and possibly head gaskets, very common problem with these, the intake gaskets go bad and the coolant actually burns in the cylinder and of course the cylinder pumps air into the coolant system because of intake gaskets being bad. :-(

If there are no coolant leaks then check your engine oil to be sure it is not over full or foamy because if there is coolant getting into the oil it will cause irreversible damage to the engine. If the engine has ever over heated the head gasket/s could also be leaking and will need replaced.

Probably upper intake manifold leaking. These have no head gasket problems.

I see a lot of lower intake gasket leaks on these but usually you get an external leak or you'll find coolant mixed with the oil, not a misfire. Upper plenum is dry on the 3.1 and just bolts onto the top of the lower intake. We usually apply pressure to the cooling system overnight with the spark plug removed from the misfiring cylinder. If there is coolant in the cylinder come morning then you only have to figure out where it is coming from. If the plenum is removed during the test you might be able to see where the coolant is or isn't coming from with a borescope by looking down the intake runner.

Bonneville, LeSabre, Park Avenue 2000-2005 Intake Manifold - Removal & Installation

3.8L Engine
VIN 1 Engine

1. Before servicing the vehicle, refer to the Precautions section.
2. Relieve the fuel system pressure.
3. Drain the cooling system.
4. Remove or disconnect the following:
   Negative battery cable Supercharger Thermostat housing Exhaust Gas Recirculation (EGR) tube at the intake manifold Engine Control Temperature (ECT) sensor Intake manifold

To install:

1. Install or connect the following:
   Intake manifold with new gaskets. Torque the bolts, working from the center out, to 11 ft. lbs. (15 Nm). ECT sensor connector EGR tube to the intake manifold Thermostat housing Supercharger Negative battery cable
2. Refill and bleed the cooling system.
3. Run the engine and check for leaks and proper engine operation.

VIN K Engine

1. Before servicing the vehicle, refer to the Precautions section.
2. Disconnect the negative battery cable.
3. Drain the cooling system.
4. Relieve the fuel system pressure.
5. Remove or disconnect the following:
   Fuel injector sight shield Air inlet duct Spark plug wires from the right side Manifold Absolute Pressure (MAP) sensor Vacuum lines from the intake manifold Fuel lines Fuel injector electrical connectors Fuel regulator vacuum line Fuel rail from the intake manifold Exhaust Gas Recirculation (EGR) heat shield Throttle cable bracket from the cylinder head mounting bracket and the throttle body cables Throttle body support bracket Upper intake plenum and gasket Thermostat housing Electrical connector from the Engine Coolant Temperature (ECT) sensor Drive belt tensioner assembly EGR valve outlet pipe Lower intake manifold
   
   
   Fig. Exploded view of the intake manifold and related components-3.8L (VIN K) engine
   

To install:



Fig. Upper intake manifold torque sequence-3.8L (VIN K) engine



Fig. Lower intake manifold torque sequence-3.8L (VIN K) engine

1. Install or connect the following:
   Intake manifold using new manifold gaskets. Torque the bolts in sequence to 11 ft. lbs. (15 Nm); then, re-torque to 11 ft. lbs. (15 Nm). EGR valve outlet pipe Drive belt tensioner assembly. Torque the tensioner bolts to 37 ft. lbs. (50 Nm). Electrical connector to the ECT sensor Thermostat housing Upper intake plenum. Torque the intake plenum bolts to 88 inch. lbs. (10 Nm). Throttle body support bracket Throttle cable bracket to the cylinder head mounting bracket and the cables to the throttle body lever EGR heat shield Fuel rail. Torque the fuel rail bolts to 88 inch. lbs. (10 Nm). Fuel lines Fuel regulator vacuum line Fuel injector electrical connectors Vacuum lines to the intake manifold MAP sensor Spark plug wires Fuel injector sight shield and air inlet duct Negative battery cable
2. Refill and bleed the cooling system.
3. Run the engine and check for leaks and proper engine operation.

Hope this help (remember rated this).

The upper intake has a egr port right next to a coolant port, the egr is exhaust gas that is recyled into the intake for emission control. On a long trip the exhaust burns a hole between the two ports causing your problem. Pretty common on the 3.8. My suggestion is to stop driving it until you have it repaired, reason being is the coolant can travel down the intake and fill up the cylinders. If that happens, worst case you can damage a rod, but you will be stranded.

The one thing I would check first is the cooling fan a quick check is with engine running turn a/c on and see if radiator cooling fans are running, if they are then we know the the fan's are good, if they don't come on check voltage at cooling fan if you have voltage bad cooling fan, turn car and a/c off, start car again with a/c off and fan's should come on at about 220deg. if they don't come on disconnect coolant temp sensor fan should come on, more then likely bad coolant sensor, now if fan don't come on you'll need check check your radiator or have a radiator flush.

As for the coolant loss issue, you may have an upper intake problem. These are made out of plastic & they will deteriorate close to an egr passage next to a coolant passage. Eventually the deterioration causes coolant to get sucked into the lower intake. WARNING, do not continue to drive it like this because it can **** enough coolant into the lower intake to "hydrolock" the eng & cause major internal damage. If you catch this problem early enough, all that is needed is a new upper intake.

U need o repair the pcv vacuum source it is the cause of the oil consumption, which is excessive crankcase pressure.