So Fix it

The Sonoma compact pickup truck was introduced by General Motors to the North American market in 1982. Sonoma pickups were known for their durable and reliable engines, but they still needed to be serviced from time to time. One of the problems the Sonoma engine could face was a blown head gasket.

Instructions

1

Disconnect the negative battery cable. Drain the engine coolant. Remove the engine cooling fan assembly. Remove the power steering pump mounting bracket. Remove the power steering pump mounting bracket stud from the cylinder head.

2

Remove the lower intake manifold. Remove the exhaust manifold. Remove the spark plug wire harness and the spark plug wire support. Remove the ground wire bolt and the ground wire from the rear of the cylinder head. Make sure you secure the ground wire out of the way.

3

Remove the bolt holding the fuel pipe bracket to the rear of the cylinder head. Now you have access to the cylinder head gasket. Remove the cylinder head and gasket. Clean the engine block and the cylinder head sealing surfaces. Clean the cylinder head bolts and the engine block bolt holes.

4

Install the new cylinder head gasket. To re-install all parts follow the same procedure in reverse.

Leaking exhaust at the engine on the 6.0-Liter GMC engine means the exhaust manifold gasket is faulty and there no longer is a good seal between the exhaust manifold and the cylinder head. To fix this leak, it is necessary to remove the exhaust manifold and replace the gasket. The exhaust manifold is secured to the cylinder head with six bolts.

Instructions

Removal

1

Lift the vehicle hood. Ensure the exhaust leak is coming from the mating surface between the cylinder head and the exhaust manifold, not the EGR valve or where the manifold meets the down pipe. Mark each spark plug wire with the paint marker to identify which wire belongs on what spark plug.

2

Turn each spark plug boot about a half turn and pull it straight off the spark plug. Do not remove any plug wires from their respective coils.

3

Remove each exhaust manifold mounting bolt with the proper size socket and ratchet. Gently pull the manifold away from the cylinder head a bit and remove the faulty gasket from the cylinder head.

Installation

4

Hold the new exhaust gasket to the exhaust manifold. Press the manifold and gasket to the cylinder head. Hand-tighten each exhaust manifold bolt.

5

Tighten the exhaust manifold bolts to 10 foot-pounds of torque with the proper size socket and torque wrench. First torque the inside bolts, then the two outside bolts. Once all of the bolts are torqued to 10 foot-pounds, repeat the same process to 15 foot-pounds of torque with the socket and torque wrench.

6

Install each spark plug wire by pushing it onto the proper spark plug. Pay attention to the marks previously made so the firing order is not disturbed. Shut the vehicle hood. Check the exhaust manifold bolt torque after the engine is warmed and cooled twice to ensure they maintain 15 foot-pounds of torque.

Developed and produced by General Motors, the 4.3L Vortec was a 4.3-liter V-6 engine used in Chevrolet vehicles. This engine was introduced in 1990 as a replacement for the 2.8-liter V-6. It is based on the bigger 5.7L V-8 GM engine, but has two fewer cylinders. GM engineers have determined precise timing specifications for the 4.3L Vortec.

Timing Definition

Ignition timing is the measurement in degrees of the crankshaft rotation at the instant when the spark plug fires the air fuel mixture while the piston is on its compression stroke.

Adjusting Timing

To set ignition timing on this engine, put the electronic spark timing (EST) in bypass mode by disconnecting the timing connector. This is a tan wire with a black stripe. This timing connector breaks out of the engine wiring harness conduit and is located adjacent to the distributor.

Timing Specification

The ideal time at which the mixture should be fully burned on the 1991 GMC with the 4.3L V-6 is set at 0 degrees of the crankshaft rotation both for the manual and automatic transmissions models.

Removing the rear window from your GMC pickup is necessary to replace it with a new one or to upgrade to an aftermarket window. Sliding rear windows, tinted windows or a new window from GM are all great options if your truck needs new rear glass. Most auto glass shops can sell you a new window or an aftermarket replacement. Some salvage yards sell replacement glass as well, but keep in mind that used glass may not hold up as well. Small stress points could cause it to break during installation.

Instructions

1

Open the doors of the truck so you can work on both sides. Then slide the bench seat as far forward as it will go. Lean the seat back forward and climb in behind the seat.

2

Slide a small, thin screwdriver between the body and the rubber gasket surrounding the window. Pull down on the gasket without prying on the glass or it will chip. All you are trying to do is get the gasket below the metal around the window.

3

Pull the gasket down several inches away from the first spot, using an additional screwdriver. Hold the gasket down and work along the edge of the window while pushing out on the glass lightly.

4

Push the glass and gasket out until the top section is outside of the body. Then pull the window up and out of the rubber gasket. Remove the gasket from the window opening by pulling it away from the body all the way around.

General Motors Company has issued three recalls for its GMC Envoy models due to airbag problems that could put vehicle occupants in danger in the event of an accident. Envoy owners experiencing airbag problems should contact National Highway Traffic Safety Administration (NHTSA) or the manufacturer to determine if they are entitled to free repairs due to these recalls.

2002 Recall

In 2002, General Motors recalled certain 2002 - 2003 GMC Envoys because, due to a manufacturing defect, the drivers side airbag inflator might fracture during a crash. Particles of the inflator could fly out and injure the driver or passengers.

2003 Recall

In 2003, GMC recalled more 2003 Envoys to repair a similar airbag inflator defect that could put drivers and passengers at risk for injury if the device explodes during a crash. The defect could also cause the airbag not to fully inflate, which could cause the airbag not to protect the driver if the inflator does not fracture.

2006 Recall

In 2006, the manufacturer recalled certain 2005 - 2006 GMC Envoy vehicles originally built with cloth seats that were later reupholstered with aftermarket leather seat cover kits. Tests showed the aftermarket seats could cause the passenger sensing system to fail, which could erroneously disable the front airbag on that side of the vehicle.