Repair 7

The fourth generation of the 1500 series pickup truck appeared in 1988 and was manufactured until 2000 by Chevrolet. There were a total of eight different versions and cab variations of the 1500. They were powered by reliable V8 engines that required periodic service if parts like the intake manifold gasket would fail.

Instructions

Removal Procedure

1

Mark the relationship of the distributor housing and rotor for proper reassembly. Remove the distributor. Unplug the upper radiator hose at the thermostat housing. Remove the heater hose at the lower intake manifold. Remove the EGR valve and the coolant bypass hose.

2

Pull out the fuel supply and return lines from the rear part of the intake manifold. Unplug the wiring harness and brackets. Remove the throttle cable and bracket. Remove the cruise control cable.

3

Take out the transmission oil level indicator tube. Remove the EGR inlet tube, clamp and bolt. Remove the PCV valve and vacuum hoses. Unscrew the air conditioning compressor. Loosen the A/C compressor mounting bracket and slide forward, but do not remove it. Lay the A/C compressor out of the way. Do not kink the air conditioning lines.

4

Remove the power brake vacuum tube and the rocker arm cover. Remove the generator rear bracket bolt. Take out the intake manifold. Remove the old pieces of gasket from the gasket surfaces. Clean the excessive carbon buildup from inside the exhaust passages and the scale and deposits from the coolant passages. Inspect the manifold for cracks, broken flanges and gasket surface damage.

Installation Procedure

5

Position the new gaskets to the cylinder head with the port blocking plates facing the rear of the engine and "This Side Up" facing up. Install the lower intake manifold on the engine. Apply sealer to the lower intake manifold bolts. Put in the lower intake manifold bolts back in place. Tighten the bolts in three steps. In the first step apply 27 inch pounds of torque. In the second apply 106 inch pound of torque and in the last step tighten the bolts applying 11 foot pounds of torque.

6

Plug in the wiring harness connectors and brackets. Connect the upper radiator hose at the thermostat housing. Install the heater hose at the lower intake manifold. Connect the coolant bypass hose.

7

Install the EGR valve and the valve rocker arm cover. Connect the fuel supply and return lines at the rear of the intake manifold. Plug in the wiring harness and brackets. Install the cruise control cable (if equipped).

8

Install the throttle cable and bracket. Put back the transmission oil level indicator tube. Install the EGR inlet tube, clamp, and bolt. Connect the PCV valve and vacuum hoses. Install the power brake vacuum tube. Install the generator and the bracket bolt (if needed). Install the air conditioning compressor and bracket. Refer to Heating and Air Conditioning. Connect the distributor. Note the relationship of the distributor housing and rotor made at disassembly.

Car engines rely on proper mixtures of air and fuel to perform at peak levels. One component of the engine, the intake manifold, helps with this mixing process, but can have problems with leakage from the intake manifold gasket.

Function

An intake manifold gasket seals the two pieces of the intake manifold assembly together to keep the air and fuel mixture from leaking out. The intake manifold itself distributes this mixture to the engines cylinders for combustion.

Considerations

Intake manifold gasket problems arise as the engine ages. Current day stock gaskets are made from nylon-filled plastic carriers, which can warp from the constant change of air pressure and heat within the intake manifolds body over the course of a vehicles lifespan. If a gasket is failing, there may be visible leakage and an obvious decrease in engine performance.

Prevention and Solution

Many aftermarket intake manifold gaskets are manufactured with aluminized steel carrier bodies to shore up the integrity of the gasket. Keep in mind that the torquing of the manifold assembly around the gasket should be monitored to make sure that the gasket is tightened securely, but is not pinched.

A vehicles intake manifold distributes the mixture of fuel and air to the engine cylinders. If the intake manifold is cracked or the mating surfaces are warped, this will cause the fuel/air to leak and the manifold must be replaced. The following instructions are general for removing and installing the manifold. The exact procedure can vary with each model, however, especially regarding the exact wires and lines connected to the manifold. It is very important that you have a manual written specifically for your model vehicle.

Removal

Because you are working on the fuel system, you need to depressurize the system. Remove the fuel pump relay from the fuse box and then start the engine until it stalls. You are also working with electrical connectors, so disconnect the negative cable from the battery. The manifold is also connected to the cooling system, so you must either drain the coolant or clamp off the coolant hose to the manifold before disconnecting it. Once all these precautions are done, disconnect all electrical connectors and lines attached to the manifold. This can include hoses from the radiator and air duct, the fuel lines, fuel rail and the fuel pressure regulators vacuum hoses, along with the electrical connectors to the crankshaft and camshaft position sensors, A/C compressor, alternator and starter. Now remove the nuts and/or bolts securing the manifold--use a torque wrench and make 1/4-turns until you can remove the bolts by hand. Remove the intake manifold.

Installation

Remove all traces of the gasket/sealant material from the engine cylinder heads with a gasket scraper, and make sure there is none on the manifolds surfaces as well. Clean those surfaces with acetone or lacquer thinner. If any material falls into the cylinder head intake ports, remove it with a vacuum cleaner. Clean up the bolts (or the manifolds studs) and apply a thin coat of engine oil to the threads. Apply a new gasket or RTV sealant to the manifolds mating surface. Make sure the intake ports, coolant holes and bolt holes are all properly aligned as you install the manifold in place and tighten the nuts/bolts. Now reconnect all the hoses, lines and electrical connectors to the manifold. Once everything is connected, you can unclamp the coolant hoses and reconnect the battery cable and fuel pump relay. Re-pressurize the fuel system by repeatedly turning on the engine for two seconds and then leaving it off for five. Start up the engine and see if oil or coolant leaks at the manifolds joints.

The intake manifold gasket helps manage the flow of intake air, coolant and oil by sealing the cylinder head to the intake manifold. You can replace the gasket yourself to save a few hundred dollars.

Parts

The cost of the parts required to repair or replace your intake manifold gasket ranges from $25 to $100 in 2010, according to RepairPal, depending on the year and make of your car. This range applies if you have a 2005 Ford Taurus or a 2011 BMW 750Li.

Labor

The cost of labor to replace the gasket is expensive relative to the cost of the parts. As of 2010, expect to pay a mechanic between $325 and $425 to replace the gasket.

Total Cost

The total cost, therefore, to have a mechanic replace your intake manifold gasket ranges from $350 to $525.

Vortec engines have a swirl port in their combustion chambers, which allows the fuel and air to mix more readily. General Motors has manufactured the six-cylinder 4.3-liter Vortec engines since 1985, primarily for use in light Chevrolet trucks made before 1995. The intake manifold is the part of the engine, and delivers the fuel/air mixture to the cylinders. The procedure for removing the intake manifold is similar for all full-size Chevrolet trucks made from 1988 to 1995.

Instructions

1

Remove the cable from the negative battery terminal with a socket wrench. Drain the coolant in the radiator into a container, and seal the container for later use.

2

Disconnect the air cleaner and the distributor with a socket wrench. Detach the cables for the cruise control and accelerator from their respective brackets.

3

Remove the bracket for the air compressor, alternator and idler pulley from the intake manifold with a socket wrench. Detach the electrical wiring and vacuum lines from the intake manifold. Disconnect the exhaust gas recirculation valve, if your vehicle is so equipped. Remove the fuel line from the intake manifold.

4

Detach the heater pipe and upper radiator hose from the radiator. Disconnect the vacuum lines for the power brakes and exhaust gas recirculation valve, if your vehicle is so equipped. Disconnect the electrical wiring from the ignition coil.

5

Disconnect any remaining brackets and sensors from the right side of the intake manifold. Detach the electrical wiring harness on the right side of the intake manifold and push it out of your way. Remove the mounting bolts from the intake manifold with a socket wrench. Detach the intake manifold and its gaskets from the engine.