How do you change the spark plugs in a '99 Lexus RX 300?

Answer 1

I can't tell you the proper way which I believe involves removing several items like the alternator and possibly the intake manifold and then unsecuring the engine and rotating it forward. I can tell you the way I did it. The first time it took me 2 hrs, the 2nd time it me 1.5 hrs so it is a matter of figuring out the little things.

1. Remove the plastic cowl on the top of the engine. Hint, after taking the 3 hex-head screws out the "Lexus" emblem screws out. 2. The front 3 spark plus are easy to remove, unplug the coil packs. 3. Unscrew the retaining bolt with a 10mm wrench. 4. Pull the coil pack straight out. 5. Use a spark plug socket and extension and unscrew the spark plugs. Reverse these steps to replace. Note: Plug gap is 44 and I would use irridium plugs. Another hint is to use silicon spray into the coil pack fittings - both the spark plug end and the electrical fitting end. A little silicon into the spark plug socket before putting in the spark plug will allow the socket to release easier when retracking the extension and socket. 6. The back three plugs are much more difficult. I removed the cruise control cable and mounting bracket from the throtle body. I also removed the PVC tubing from the left side of the intake manifold. You should then be able to insert each of your hands into the respective openings, you pretty much have to perform the rest of the steps blindly. The space is tight but I have done it 3 times now and can say that it can be done and probably easier then the factory method. 6. This will be the hardest part, unplug the the coil packs. 7. Unscrew the retaining bolt with a 10mm wrench. 8. You won't be able to pull the coil packs straight out but you can get them out but move slowly so as to not damage the coil packs - they are around $100 a piece. 9. It will be easier to get at the spark plugs if you first drop in the spark plug socket, then insert the socket extension. Make sure you get the extension plugged into the socket and then the socket secured on the spark plug. Then wiesel a socket wrench in and plug it into the extension. To crack loose the spark plugs from the right side (socket wrench handle pointed to the right) you will push toward the firewall, on the left side (socket wrench handle pointed to the left) you will pull towards you. After cracking the spark plugs loose you should be able to remove the socket wrench and using your fingers on the end of the extension unscrew the plugs. 10. To reinstall the plugs insert the plug into the socket first and remember the silicon spray into the socket, then wiesel the plug, socket and extension into the spark plug hole. Tighten the spark plug as tight as possible with your fingers. Perform final tightening with the socket wrengh. 11. Replace the coil packs and remember the silicon spray. Secure them with the retaining bolts. 12. Plug in the coil pack electrical fittings. 13. Reinstall the cruise control mounting bracket and cable, reinstall the PVC tubing and the the engine cowl and you are done.