In 1987, the 4.3L TBI engine began using roller valve lifters instead of the standard flat bottom lifters. The roller lifter is still hydraulic requiring no valve adjustment. The roller lifter incorporates a roller that rides along the cam lobe reducing friction and component wear. A roller lifter restrictor and retainer is needed to keep the lifter from turning in the bore while the engine is running. All 2.5L TBI engines incorporate the roller lifter configuration.
REMOVAL & INSTALLATION
Valve lifters and pushrods MUST be kept in order so they can be reinstalled in their original positions.2.5L Engine
See Figures 1 and 2
This engine uses hydraulic lifters that are equipped with rollers to reduce engine friction.
- Refer to the Rocker Arm, Removal and Installation procedures in this section, then loosen the rocker arms bolts, move the rocker arms aside and remove the pushrods.
- Refer to the Pushrod Cover, Removal and Installation procedures in this section and remove the pushrod cover.
- Remove the hydraulic lifter retainer studs, the retainer(s) and the guides. Lift the hydraulic lifter from the engine block.
Inspect the hydraulic lifter for:
Wear or scuffing.
If the hydraulic lifter is found to be defective, replace it. If installing a new lifter, be sure to remove all of the protective sealant from inside the body, then lubricate it and the roller with engine oil.To install:
- Install the lifters and retainers. If you are installing the old lifters, MAKE SURE they are being returned to their original positions.
- Tighten the lifter retainer-to-engine studs to 96 inch lbs. (11 Nm).
- Install the pushrods and reposition the rocker arms. Adjust the valve lash as detailed earlier in this section or in General Information & Maintenance of this information.
- Install the pushrod cover as outlined earlier in this section.
- Install the rocker arm cover as outlined earlier in this section.
See Figures 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and 13
Some of the early 4.3L engines covered by this guide (1985-86 models), use a hydraulic lifter without a cam roller. All 1987 and later 4.3L engines use roller lifters. The removal procedures are basically the same except the roller lifters have retainers and guides (which are necessary to keep them from turning while the engine is running) that have to be removed to free the lifters.
- Refer to the Intake Manifold, Removal and Installation procedures in this section and remove the intake manifold.
- Refer to the Rocker Arm Cover, Removal and Installation procedures in this section and remove the rocker arm cover(s) from the engine.
- Refer to the Rocker Arm, Removal and Installation procedures in this section, then loosen the rocker arm nuts, move the rocker arms aside and remove the pushrods.
Either work on only one lifter at a time, or label/arrange the pushrods to be assured that you can install them back to their original locations.
- For 1987-93 models, remove the bolts from the lifter retainer, then remove the retainer from the lifter valley in order to access the lifter restrictors. Usually there will be 6 restrictors (one per cylinder or one per pair of lifters). Remove the restrictor for the lifter(s) you are servicing.
- For 1994-96 models, remove the bolts from the retainer which is being removed. There is usually one on each side of the lifter valley.
- Grasp the hydraulic lifter and remove it from the cylinder block, using a twisting action. If necessary use the GM Lifter Remover tool No. J-3049 (pliers type). In some cases, pliers can be used, but be careful not to score or damage the lifter.
- If any lifters are stuck in the cylinder block, use the GM Lifter Removal tool No. J-9290-01 (or an equivalent slide hammer type tool) to pull the hydraulic lifter from the cylinder block.
When removing the hydraulic lifters, be sure to place them in an organizer rack so that they may be reinstalled in the same engine bore from which they were removed.
Inspect the lifters for:
Wear or scuffing.
If a new camshaft has been installed, install all new hydraulic lifters. If a new camshaft or new lifter(s) have been installed, add engine oil supplement to the crankcase.To install:
- When new lifters are installed they should be coated using either a high viscosity oil with zinc (such as GM 12345501) or with a suitable engine pre-lube. It's also usually a good idea to prime any hydraulic lifter by submerging it in fresh engine oil and pumping the plunger gently a few times. This will provide lubrication to the internal components before assembly.
GM recommends that whenever a new camshaft and/or a set of new lifters has been installed, that you change the engine oil and filter, and then add GM engine oil supplement 1052367 to the engine oil upon refill.
- Install the lifters. If you are reusing the old lifters MAKE SURE each is installed in the same bore from which it was removed.
- Install the lifter retainer (and separate restrictors on 1987-93 models), then tighten the bolts to 12 ft. lbs. (16 Nm).
- Install the pushrods and rotate the rocker arms back into position. Adjust the valve lash.
- Refer to the Intake Manifold, Removal and Installation procedures in this section and install the intake manifold.
- Install the rocker arm cover(s).