Blown upper air intake manifold on gm 3800 series two engine

Check the trouble codes. there must be a code or a pending code if the CEL came on. Post them here, or you can google the codes for lots of information-descriptions, and possible causes and remedies. Autozone, O'Reilleys, probably others will do code scans for free.

How many miles on it? That engine was prone to upper and lower intake manifold gasket failure, although GM might have corrected the problem gaskets by '04.

Check the fuel pressure. It will tell you if the pump, fuel filter, and fuel pressure regulator are all good. Fuel pressure is critical on fuel injected engines.

Check your spark plugs for wear or the wrong gap.

Another possibility is a vacuum or air leak. Check all vacuum hoses and the intake manifold gasket. The GM 3.8L engine is prone to lower intake manifold gasket failures. Sometimes the upper intake gasket, too.

You should not have to bleed the fuel system. If everything is functioning properly it should bleed the air automatically just by cranking over for a few seconds. is it possible you left an electrical connector unplugged? It sounds like maybe the injector harness or one of the coil connectors is not plugged in. I would check all the connectors you can to make sure they are plugged in and fully seated.

The upper intake manifold, or plenum, is notorious for leaking coolant internally into the engine. Replacements are available from many aftermarket sources.

Advice of Haynes manual is worth it . But to answer your Intake ?? if it is intake manifold gasket there are 3 of them . The upper planium is the Aluminum part the Air intake hose attaches TOO - a common GM loss of pressure gasket causing rough idle / drivebility issues . Then # 2 gasket is lower intake mounting to antifreeze carrying Intake manifold same air pressure loss. ## 3 is Intake base mounting to cylinder heads and has coolant carried in it to keep air / fuel mix charge cold . Now U see you did not remove cylinder heads so the Timing belts or heads not have been disturbed = no need to set timing . Timing is set by computer via sensors and Belt Load / Tension under Rpm . If you have loose / worn out Timing belt then engine will rattle when applying power in gear with foot on brake - it may stall under test I described and not want to restart - That would be reason to Look at resetting Timing issues . Good luck .

3.8L Engine (most common) Upper Intake Manifold To Remove:

1. Drain the cooling system.
2. Remove or disconnect the following:
   • Negative battery cable.
   • Fuel injector sight shield.
   • Air cleaner intake duct.
   • Right spark plug wires from the ignition control module and reposition.
3. Relieve the fuel pressure.
4. Remove or disconnect the following:
   • Fuel rail assembly.
   • Brake booster hose from the vacuum source manifold in the upper intake manifold.
   • Exhaust Gas Recirculation Valve (EGR) wiring harness heat shield nut, bolt and the EGR heat shield.
   • Throttle body support bracket upper bolt.
5. Disconnect the electrical connectors from the following:
   • EVAP purge solenoid
   • Throttle Position (T/P) sensor
   • Idle Air Control (IAC) valve
   • Manifold Absolute Pressure (MAP) sensor
   • Mass Air Flow (MAF) sensor
   • EVAP purge solenoid vacuum line from the throttle body.
   • Accelerator and the cruise control cables with the bracket from the throttle body.
6. Remove or disconnect the following:
   • Upper intake manifold bolts and stud.
   • Clean the upper intake manifold bolt threads.
7. Remove or disconnect the following:
   • Upper intake manifold by lifting the back of the intake and sliding the manifold forward from the throttle body support bracket.
   • Upper-to-lower intake manifold carrier gasket from the upper intake manifold.
8. If the upper intake manifold is being replaced, remove the following:
   • Throttle body assembly.
   • Manifold Absolute Pressure (MAP) sensor.
   • Positive Crankcase Ventilation (PCV) valve.
   • Vacuum source manifold.

Upper intake manifold bolt torque sequence (3.8L engine)

To Install:

1. If the manifold was replaced, install or connect the following:
   • Vacuum source manifold.
   • Positive Crankcase Ventilation (PCV) valve.
   • Manifold Absolute Pressure (MAP) sensor.
   • Throttle body assembly.
   • Upper-to-lower intake manifold carrier gasket to the upper intake manifold.
2. Carefully place the upper intake manifold onto the lower intake manifold. Ensure that the alignment pins in the upper intake manifold align with the holes in the lower intake manifold. NOTE: Apply thread lock compound, to the bolt threads before assembly.
   
3. Install or connect the following:
   • Upper intake manifold. Tighten the upper intake manifold bolts in sequence to 89 in lbs (10 Nm)
   • Accelerator and the cruise control cables with the bracket to the throttle body.
   • EVAP purge solenoid vacuum line to the throttle body.
4. Connect the electrical connectors to the following:
   • Mass Air Flow (MAF) sensor
   • Manifold Absolute Pressure (MAP) sensor
   • Idle Air Control (IAC) valve
   • Throttle Position (T/P) sensor
   • EVAP purge solenoid
5. Install or connect the following:
   • Throttle body upper support bracket bolt. Tighten the bolt to 89 in lbs (10 Nm)
   • EGR valve wiring harness heat shield, nut and the bolt. Tighten the nut and the bolt to 89 in lbs (10 Nm)
   • Brake booster hose to the vacuum source manifold.
   • Fuel rail assembly.
   • Right spark plug wires.
   • Air cleaner intake duct.
   • Fuel injector sight shield.
6. Connect the negative battery cable.
7. Fill the cooling system.
8. Inspect for fluid or vacuum leaks.

Lower Intake Manifold (W/O Supercharger) To Remove:

1. Remove or disconnect the following:
   • Upper intake manifold.
   • Generator brace.
   • Drive belt tensioner with the mounting bracket and the heater water bypass inlet pipe.
   • Exhaust gas recirculation EGR outlet pipe bolt from the lower intake manifold.
   • Radiator inlet hose from the water outlet housing.
   • ECT sensor electrical connector.
   • Right upper engine mount strut bracket.
   • Generator brace bracket bolts.
   • Generator brace bracket.
   • Lower intake manifold bolts.
   • Lower intake manifold.
   • Lower intake manifold seals.
   • Lower intake manifold gaskets.
2. If replacing the lower intake manifold, Remove or disconnect:
   • Water outlet housing bolt and stud
   • Water outlet housing
   • Gasket and the thermostat.
   • ECT sensor.
3. Inspect the flatness of inlet flanges.
4. Clean the intake manifold mating surfaces.
5. Clean the intake manifold bolts and bolt holes of adhesive compound.

To Install:

1. If removed, install the ECT sensor.
   • Tighten the ECT sensor to 18 ft. lbs. (25 Nm)
2. If removed, install the thermostat, the gasket, and the water outlet housing.
3. If removed, install the water outlet housing bolt and the stud.
   • Tighten the bolt and stud to 20 ft. lbs. (27 Nm)
4. Install or connect the following:
   • Lower intake manifold gaskets. NOTE: Apply sealer GM P/N 12346286 (Canadian P/N 10953472) or equivalent to the ends of the intake manifold seals.
     
   • Lower intake manifold seals.
   • Lower intake manifold.
   • Lower intake manifold bolts.
   NOTE: Apply thread lock compound GM P/N 12345382 (Canadian P/N 10953489) or equivalent to the two hidden bolts and ensure they are installed.
   
5. Tighten the lower intake manifold bolts in sequence to 11 ft. lbs. (15 Nm)
   
   
6. Install or connect the following:
   • Generator brace bracket.
   • Generator brace bracket bolts. Tighten the bolts to 37 ft. lbs. (50 Nm)
   • Right upper engine mount strut bracket.
   • ECT sensor electrical connector.
   • Radiator inlet hose to the water outlet housing.
   • EGR outlet pipe to the lower intake manifold.
   • EGR outlet pipe bolt to the lower intake manifold. Tighten the bolt to 21 ft. lbs. (29 Nm)
   • Drive belt tensioner.
   • Generator brace.
   • Upper intake manifold.
7. Inspect for leaks.

Lower Intake Manifold (W/ Supercharger) To Remove:

1. Disconnect the negative battery cable.
2. Drain the cooling system.
3. Remove the supercharger.
4. Remove the thermostat housing.
5. Remove the EGR pipe at the intake manifold.
6. Disconnect the electrical connection at the temperature sensor.
7. Remove the intake manifold and gaskets.

NOTE: The coolant bypass tube will release from the intake manifold when the manifold is removed.
To Install:

1. Clean the gasket sealing surfaces.
2. Install the intake manifold gaskets.
3. Align the coolant bypass tube with the opening in the intake manifold and install the manifold. Tighten the bolts to 11 lb ft (15 Nm).
4. Install the electrical connector to the temperature sensor.
5. Install the EGR pipe to the intake manifold.
6. Install the thermostat housing.
7. Install the supercharger.
8. Fill the cooling system.
9. Connect the negative battery cable.

You have a blown head gasket. The engine will have to be dissembled and the head gaskets replaced. At that time you can find out how much damage was done and what parts need replacing. You may end up needing a complete overhaul. A used engine is an option if you can find a good low mileage one.

Never have seen blown headgaskets on a 3800 engine. Buick dealer parts guy over 20 years. You need a new upper intake manifold as it has leaked coolant into the combustion chamber. Also new plugs as you will have to remove them to get the coolant out. Common problem .

DO NOT DRIVE THE CAR until this problem is fixed! You could destroy the engine.

Many GM V6 engines of 1995-1999 had defective Upper Intake Manifold (UIM) gaskets (this is especially true for 3800 V6 engines). The antifreeze/coolant (especially orange DEX-Cool) will deteriorate the gasket material over time. If there are abnormal exhaust noises accompanying the leak, and/or the oil appears cloudy (check this immediately), you may have a blown head gasket or Lower Intake Manifold (LIM) gasket. Start with the UIM gasket.

The repair is detailed in the Haynes manual for that car ($17 at NAPA and Carquest), and (DIY) will take 5-8 hours plus a new gasket and RTV sealant (parts should be under $40 for all). A shop will charge $250-350 for this job.