Torque Spec for '99 Chevy C1500 5.7L engine lower intake manifold

Call any major autoparts store for the correct answer. There are updated torque specs for the gm 3.4 vs in order to deal with a common issue of leaking intake manifold gaskets. They should have the correct updated spec for you vehicle based on the specific Vin number

Fig. Intake manifold bolt torque sequence 2.7L engine

Upper intake manifold with a new gasket on the lower intake manifold and torque the bolts, in sequence, to: 105 inch lbs. (12 Nm)

Hope helps (remember to rate this answer). Good job.

(step 1 ) the torque specs for the heads are---1998 through 2001 are 37 foot lbs. ( step 2) rotate an additional 90-degrees (1/4 turn). intake manifold bolts ( lower ) step 1-- 62 in-lbs, step 2--115 in-lbs. intake manifold bolts/studs ( upper ) 18 ft-lbs. this is for the 3.1 v-6, have a good day!

3.4L Engine To Remove:

1. Remove the lower intake manifold.
2. Remove the exhaust crossover pipe.
3. If removing the right cylinder head, remove the catalytic converter from exhaust manifold.
4. If removing the left cylinder head, remove the engine oil dipstick and tube.
5. Remove the rocker arms and pushrods.
6. Remove and discard the cylinder head bolts.
7. Remove the cylinder head.
8. Clean the mating surfaces on the following items:
   • Cylinder head
   • Cylinder block
   • Intake manifold
9. Clean the cylinder block bolt threads.

NOTE: During disassembly, keep the valve train components together for proper location during assembly.
To Install:
NOTE: Coat the cylinder head bolt threads using thread sealer.

1. If removed, install the following components:
   • Exhaust manifold
   • Accessory studs
   • Spark plugs
2. Place the cylinder head gasket in position over the dowel pins. Ensure that the THIS SIDE UP note is showing.
3. Install the cylinder head. Cylinder head torque sequence ’99-‘00
   
   Cylinder head torque sequence ’01-05
   
   
4. Install the new cylinder head bolts.
   • Tighten the cylinder head bolts a first pass to 44 ft lb (60 Nm).
5. Tighten the cylinder head bolts in sequence an additional 95 degrees.
6. Install the intake gasket.
7. Install the pushrods and rocker arms.
8. Raise and support the vehicle.
9. Install the catalytic converter and dipstick tube and indicator if removed.
10. Lower the vehicle.
11. Install the exhaust crossover pipe.
12. Install the intake manifolds.
13. Connect negative battery cable.
14. Fill the cooling system.

These engines are legendary for intake manifold gaskets leaking, and this is exactly what's happening with this one. Yes, you will have to remove the intake manifold, and to do so, you will need the torque diagram to remove it, and also to torque the new one. It's best that you buy a Haynes manual so you know the exact procedure; it's a $15 insurance that you will be glad to have. If you aren't having problems with the head gaskets, I'd leave them alone personally, but if you want to undertake these, now would be the time to do so, as there's not a lot more to take apart. Main suggestion though, is to be absolutely sure you keep the push rods in the exact order and orientation, as they each have a unique wear pattern with the lifter. Changing them can cause them to lose their seal, depriving the valve of oil, and ruining your head.

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).

2.2L Engine & 2.4L Engines
These engines are not equipped with rocker arms. The camshafts directly actuate the valves.

3.1L Engine & 3.4L Engines
When install or connect the check the following:
- Pushrods and the rocker arms. Torque the bolts to 24 ft. lbs. (32 Nm). - Rocker arm cover using a new gasket. Torque the rocker cover bolts to 89 inch lbs. (10 Nm).
- Heater bypass pipe. Torque the screw at the water pump to 106 inch lbs. (12 Nm), the bolt at the cylinder head corner to 18 ft. lbs. (25 Nm) and the nut to 18 ft. lbs. (25 Nm).


About the INTAKE MANIFOLD...
- Intake manifold nuts and bolts and tighten to 89 inch lbs. (10 Nm)
- Pushrods and rocker arms. Torque the bolts to 89 inch lbs. (10 Nm) plus an additional 30 degree turn. - Lower intake manifold. Apply sealant to the threads of the bolts and torque the bolts to 115 inch lbs. (13 Nm).





Exploded view of the upper and lower intake-3.1L & 3.4L engines




Fig. Lower intake manifold tightening sequence-3.1L & 3.4L engines

Hope help.

3.8L Engine

NOTE The 3.8L (VIN K) non-supercharged engine uses a two-piece intake manifold consisting of an upper air plenum which mounts the throttle body and a lower intake manifold assembly which houses the fuel injectors. The 3.8L (VIN 1) supercharged engine uses a similar lower intake manifold. The supercharger serves as the upper manifold.
Lower Manifold

NOTE Two bolts which fasten the lower intake manifold to the cylinder head are accessible only after the upper intake manifold is removed. These bolts are located in the right front and left rear corners of the lower intake manifold. Remove the upper intake manifold to service the lower intake.
The 3.8L (VIN 1) supercharged engine uses a manifold similar to the 3.8L (VIN K), but the supercharger serves as the upper manifold.

1. Disconnect the negative battery cable.
2. On 3.8L (VIN 1) engines, remove the supercharger assembly. Please see the procedure in this section.
3. Remove the upper intake manifold using the procedure above.
4. Remove the EGR outlet pipe from the intake manifold.
5. Detach the engine coolant temperature sensor wiring harness from the sensor.
6. Remove the lower intake manifold bolts and carefully lift off the manifold.

To install:


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

1. Clean all parts well with degreaser, especially the gasket seal surfaces on the upper and lower manifold pieces and between the lower manifold and the cylinder heads..
2. Install new gaskets to the cylinder heads and new seals to the engine block. Carefully lower the manifold into place. Apply thread-locking compound to the bolt threads. Make sure to install the two hidden bolts in the lower intake manifold. Hand start all bolts, then torque evenly to 11 ft. lbs. (15 Nm). Follow the toque sequence, starting in the center, then working outwards in a circle.
3. Install the remaining components in the reverse order of the removal process.

Upper Intake Manifold (Plenum)

1. Disconnect the negative battery cable.
2. On 3.8L (VIN 1) engines, remove the supercharger assembly. Please see the procedure in this section.
3. Tag for identification, then remove the right side spark plug wires.
4. Disconnect the ignition wires from the fuel rail.
5. Remove the fuel rail. Please see Section 5.
6. Remove the cable bracket from the intake manifold.
7. Remove the throttle body.

NOTE Two bolts which fasten the lower intake manifold to the cylinder head are accessible are accessible only after the upper intake manifold is removed. These bolts are located in the right front and left rear corners of the lower intake manifold.

1. Remove the upper intake manifold bolts and carefully lift the upper intake manifold from the engine.

Fig. Upper intake manifold and bolt torque sequence-3.8L (VIN K) engine
To install:

1. Clean all parts well with degreaser, especially the gasket seal surfaces on the upper and lower manifold pieces.
2. Install new gaskets to the cylinder heads and new seals to the engine block. Carefully lower the manifold into place. Make sure to install the two hidden bolts in the lower intake manifold. Hand start all bolts, then torque evenly to 89 inch lbs. (10 Nm). Follow the torque sequence, starting in the center, then working outwards in a circle.
3. Install the remaining components in the reverse order of the removal process.

The corners of the intake manifold have coolant pasages. The lower intake manifold gasket will need to be replaced. There is an updated manifold gasket, manifold bolts, and torque specification. Call the chevrolet dealership and see if they will extend the warrant on this repair. It is a very common problem with this engine. Thanks Steve