4A-G Valve Adjustment

If you hear a lot of upper-engine noise on the 4A-G, you most likely have valve clearances that are out of spec. Another symptom is a slight loss in power and/or cylinder compression. Your Toyota dealer will charge $300+ for this service, so if you're comfortable doing this job, by all means, save your money! Conversely, once you've read through this a few times, consulted your experienced friends, and it still sounds confusing, don't go anywhere near the head. As always, I take no responsibility for your screw-ups!

Tools and parts you need:
• 3/8" ratchet and 10 mm socket to remove valve cover acorn bolts.
• Spark plug socket along with a long extension.
• 1/2" ratchet, an extension, and 17 mm socket to turn crank.
• Flat blade feeler gauge with a range of 0.002-0.020" or more.
• An accurate caliper or micrometer (I use the Mitutoyo 293-768-30 mike w/ a digital readout to make things easier on me) to measure valve shims.
• The SSTs to compress and hold the valve lifters would be nice, but you can get away w/ using one or two screwdrivers; Snap-On YA8825 ($36) (this should include the holding tool, YA8825-1 for $12.50, so make sure that it's included!).
• An assortment of shims pillaged f/ donor cars at the junkyard. If you find that none of the ones that you have will fit, only then should you go to your dealer and plunk down $10 for a new shim.
• Download (right click, then "save target as") and print out my valve clearance worksheet at the bottom of this page. Fill out each data box as you go through each valve in the proper order. It'll make things easier for you.

Some common compatible valve shim donors:
• 16-valve 4A-G(Z)(E)
• 4A-F(E)
• 7A-FE
• 7M-G(T)E
• 3S-G(T)E
• 5S-FE (pre-'93)

Prelimenary procedures:
1. Make sure that the engine is dead cold so that the clearances aren't off.
2. Get all of the crap outta the way so you can pull the valve covers: Cables, wires, valley cover, hoses, etc.
3. Remove the valve covers and make sure you don't lose the nuts and gasket-washers.
4. Remove the spark plugs. Loosen them all the way, but leave them in their holes so that nothing falls in.
5. Jack up the front end, remove the right front tire, and set the car down on a jackstand.
6. Remove the right engine cover to access the crankshaft pulley.
7. Turn the crank clockwise until the #1 cylinder is at TDC. How do you know which cylinder is #1 and not #4? The spark plug cords are numbered; #1 cylinder is closest to the drive belt side of the engine. The timing mark on the crank pulley should match up with the 0° timing mark. Also, the intake cam (it should be exposed by now), should have a little notch in the general area of the oil filler hole facing up. You can even pull the #1 spark plug and visually inspect that the piston is indeed at TDC.

You won't be checking the valve clearances all at one time. You only check half of 'em at a time. When Cylinder #1 is at TDC, Check only the valves that are in RED. Slide your flat blade feeler gauge in between the cam lobe and the valve shim. Write down the biggest blade that'll fit without too much friction.

When you're done checking the valves at #1 TDC, turn the crank 1 complete revolution, or 360°. Again, make sure that the timing mark on the crank pulley matches the 0° timing mark. This time, you won't be able to see the little notch on the intake camshaft. Check that #2 is at TDC. Now, you'll be checking the other half of the valves that are marked in RED. Make sure that you write down each valves clearances.

At this point, I like to re-check all of the valves, again. That way, you know that your numbers won't be off. I know that this pretty much doubles the work, but hey, you only do this every 60,000 miles! It's all 'bout reproducible results, baby!

So, now you've got a whole bunch of numbers in your hand. What do you do now? Well, you take each valve's clearances and make sure that they're within specs. For those valves that are out of spec, remove the shims one-by-one and measure them with the caliper. Write these numbers down according to which valve they came from. Here are the valve clearance specs for a cold 4A-GE:

Intake Valves Out of Spec
Here's how you figure out which shim to use to return the intake valve clearances to spec.

Exhaust Valves Out of Spec
And here's how to figure out the new shims for the exhaust valves.

Pick a shim that's closest to the N value you came up with.

If you can do a little creative "juggling," you may be able to use your old shims from the out-of-spec valves. That way, you can save a little money. For the shims that you do need to buy, make sure you know the thickness of the shims you need--for some reason, the parts book at the dealerships don't list 'em by the shim number--they do it by the thickness.