I have a 1983 Toyota pickup with 22R motor with 284,000 miles and no major engine work. Oil consumption became high - about one quart every 500 miles. At first, I thought the oil was leaking from the front crankshaft seal. I replaced the seal, and the leakage stopped, but oil consumption was still high. Then I started noticing a little blue smoke from the tailpipe, and I found the spark plugs fouled with lots of deposits, so I realized the motor was burning oil.
I checked compression and found good pressure and uniformity in all four cylinders. Next, I wanted to try replacing the valve stem oil seals to reduce oil consumption, since valve seals are very inexpensive, but my factory manual only described replacement with the head removed. The rocker assembly can only be removed by removing the head bolts. I searched the internet, but I couldnít find any way to replace the seals without removing the head - or at least without removing the head bolts. After I thought about it for awhile, I came up with a way to replace the seals - without removing the head bolts - that worked great for me, and Iím posting a description of the method here:
1. Set the emergency brake good and tight.
2. Remove valve cover and spark plugs.
3. Before you proceed further, make sure you have no distractions, clear your mind, and give this your full attention. If you lose your concentration, you may drop a valve down inside the cylinder and then youíll suffer from much regret (and also humiliation if others are present) because youíll have to remove the head. Stay focused.
4. Rotate crankshaft by hand with a wrench to top dead center (using timing marks). Find the cylinder that is at the top of the compression stroke (both valves closed with both cam lobes pointing down away from rockers). On that cylinder, carefully mark the position of the slots of the valve adjusters on the rockers with a sharp permanent marker so it will be easier to readjust the valves later.
5. Remove one of the valve adjusters.
6. Put the transmission in a forward gear (I used 3rd). Rotate the crankshaft by hand just past top dead center until it stops turning when the play in the drive train is taken up. Apply air pressure to the cylinder through a fitting on the spark plug hole (I used about 60 psi pressure). Compress one of the valve springs (the one under the rocker with the removed adjuster) with a valve spring compressor tool such as Item #909397 from NorthernTool.com ($12.99 plus shipping) - also found in your local auto parts store. Tap on top of the tool lightly with a hammer to free the spring retainer from the valve keepers, and remove the valve keepers (I used a pencil-sized magnet). Remove the valve spring compressor tool.
7. Release the air pressure on the cylinder. The valve will drop down a little bit until it rests on the top of the piston. Put the transmission in neutral. CAREFULLY and slowly rotate the crankshaft by hand a little farther past top dead center until the valve stem drops down far enough to allow removal of the valve spring from between the head and rocker. BE CAREFUL: If you rotate the crankshaft too far, the valve will fall down inside the cylinder. Slide the rocker over as far as it will go on the rocker shaft, and remove the valve spring retainer and then remove the spring.
8. Remove the old valve seal with a pair of pliers (I found that my exhaust valve seals were crumbling). Lube up the new seal with oil and slide it over the valve stem (the seals I purchased from Advance Auto Parts came with a nice plastic sleeve to use to protect the seal from damage by the valve keeper groove on the valve stem). Tap the seal very lightly around the outer edge (not on the lip) using a small piece of wood as a punch and a hammer until the seal is snugly seated on the valve guide.
9. Reinstall the valve spring and retainer. CAREFULLY rotate the crankshaft back to top dead center to lift up the valve stem. Using a thin piece of wood shim inserted between the coils of the valve spring, lever and lift the valve up until it is fully closed. The new seal will hold the valve in place.
10. Put the transmission in a forward gear. Rotate the crankshaft by hand just past top dead center until it stops turning when the play in the drive train is taken up. Apply air pressure to the cylinder to hold the valve in the closed position. Compress the valve spring with the tool, and install the valve keepers. Remove the valve spring compressor tool. Release the air pressure on the cylinder. Reinstall the valve adjuster and locknut on the rocker and check the clearance.
11. Repeat the process (Steps 5-10) for the other valve on the same cylinder.
12. Rotate the crankshaft 180 degrees (one half turn) so that another cylinder is at top dead center of the compression stroke.
13. Repeat the process (Steps 4-12) until all valve seals are replaced.
14. Reinstall spark plugs and valve cover.
15. Recheck valve clearances with the engine hot, as specified in the manual.
After 500 miles, it looks like my 22R hasnít used a drop of oil. I think Iím good for at least another 100,000 miles on this engine.