Adjusting Valves

FJ40's have manually adjustable valve clearance. We'll adjust them in this video. This adjustment needs to be done periodically to maintain best engine performance. If there is too much clearance, the valves don't open enough which means less power. If there's not enough clearance, valves may not close completely when the engine is hot. This reduces compression, robs power and may cause the valves to burn out. After the adjustment, I did another compression test. The first compression test back in October showed very low compression of 68 psi on the number 4 cylinder. This time, we got 121. If that seems low to you, remember the test was done at 6,000 feet. Adjusted to sea level, that's 134 psi. The other 5 cylinders were all around 132 psi (144 sea level). The factory service manual says to rebuild the engine at 128 psi. This means we can leave the engine alone for now.