REMOVAL & INSTALLATION
See Figures 1 through 5
While the jet valve is replaced as an assembly rather than being serviced, you can disassemble it to inspect it and replace the valve stem seal. You should use tool MD 998309 or equivalent.
- Disassemble the jet valve with the special tool used as a spring compressor. The forked portion of the tool fits over the ridge at the center of the assembly while the hole in the upper section fits over the valve stem. Compress the spring enough to remove the keepers and remove them; then slowly release the pressure.
- Disassemble each jet valve assembly so all parts are kept together. Check the seat and valve faces for any signs of burning or cracks. Make sure the valve slides in the jet body smoothly and without play. If there are any signs of burning or excessive valve stem wear, the jet valve assembly must be replaced. Inspect the spring for cracks of any kind, and replace defective springs.
- Coat the valve stem with clean engine oil and insert it into the jet valve body. Sit the assembly on a flat surface, place a new seal squarely over the valve stem, and install the seal with the special installation tool, tapping downward on it gently with a hammer. Make sure the valve stem still moves up and down smoothly after the seal is installed; if movement is not smooth, the seal has been damaged or is not installed squarely.
- Install the spring and spring retainer, compress the spring with the special tool and install the keepers, making sure they remain squarely in the valve stem groove until tension is removed and the retainer covers them. If they do not lock in place securely, the valve spring could pop out either as you are working on the engine, or later, when the engine is operating.
- Coat a new O-ring with clean engine oil and coat the threaded area and sealing areas of the jet body. Install the new O-ring into the groove provided for it. Then, insert each jet valve squarely into the hole in the cylinder head and start the threads carefully. Use the special socket and a torque wrench to tighten the assembly to 13-15 ft. lbs. (18-20 Nm) keeping the wrench square to the valve stem at all times.
Before reassembly, check that all lapping compound has been cleaned from the head. Remember that each piece being reused must be reinstalled in its original position.
- Position the spring seat on the head. The seat will be forced into its final position in the next step.
- Install the valve stem seals and insure proper installation of the spring seats.
- Thoroughly coat the valve stem with clean engine oil. Insert the valve slowly from underneath, guiding it gently through the new seal. Make sure the valve will slide up and down smoothly, indicating the seal is in proper position.
- Install the valve springs with the color-coded end facing upward. Install the retainer on top of the spring. Compress the retainer with the valve spring compressor until the retainer sits below the groove in the valve stem.
- Install the keepers, making sure they stay properly positioned in the stem groove, and release the tension on the compressor slowly. Note that if the keepers do not sit squarely in the grooves, the valve spring tension could be released suddenly either as you work, or later as the vehicle is in operation. Once the keepers have locked securely, remove the valve spring compressor.
- Repeat the sequence for each intake and exhaust valve.
After valve spring assembly installation tap the top of the valve springs to make sure the valve keepers are seated properly.