Valve adjustment

Valves don't always get noisier. Just as often, a valve face "erodes" which allows the valve to recede into the head, thereby reducing the lash clearance. Your valves get quieter and soon BURN from *insufficient* clearance. While this is not common with Toyota, it can happen. So pull the valve cover and get out your feeler gauges.

--
- Philip @ Maximum Torque RPM

Phil , will adjusting make a milage or performace difference. My milage is a bit low

Ain't broke. Don't fix it.

Depends. Don't ya love that one? LOL If the valves are out of tolerance to the tight side, then probably an improvement in fuel mileage, low end torque, and idle quality would result from readjustment. If the valves are out of tolerance to the loose side, then one might expect an improvement in mid range power, albeit small, from readjustment.

"A slightly tappy valve is a happy valve"

--
- Philip @ Maximum Torque RPM

IN this arena, you are in error. By your reckoning, don't adjust the valves until they are burned. That's dumb.

--
- Philip @ Maximum Torque RPM

Ahem,...showing your age there Phil,...tappy is happy? Adjust them by micro-increments until their quite.... ~(8^I)

Jason

You could use a loosening of your overhead adjustments, Jason. Some engines have valve trains that are inherently noisier than others. My 2003 Corolla is a good example. You would not start closing up the valve lash just to obtain "quiet."

"Micro-increments" LOL BTW, the word is spelled *quiet*.

-- ~Philip

"Today is Earth Day so ... you golfers ... put back your divots!"

I am a first time owner of a '99 camry 4 cyl. Looking through the manual I find reference to valve adj. check at 60,000 miles. Also under the hood there is a listing of cold and hot valve clearences. Does the 4 cyl not have hydraulic lifters etc.? What is the charge for this service (USA)? Will valve noise become a problem with high miles? Thanks for some insight on this question. jfj

It's not so much adjust valve clearance as it is "check" valve clearance. Change the oil regularly and they're likely to be fine. There is no threaded adjustment as with rocker arms. There are no rocker arms. The cams operate directly over the valves through a lifter. Actually, the "lifter" presses the valve downward. Suppose the term is a carryover from push rod designs where the lifter actually "lifted." I need to reminded myself not to call the cover a "rocker arm cover." It's almost like you have solid lifters pre set at the factory, only difference being there is a shim on top that can be replaced to adjust clearance. But you need some special tools to hold the edge of the lifter down while you remove the shim. I think someone one said they managed this with a large screwdriver, but not sure on that one. With the cam operating directly over the "lifter" reciprocating mass is minimized. Also, with the multi valve design, valves are smaller and lighter and valve springs require less tension to operate correctly. All this reduces wear on the "valve train." Actually, there isn't much of a "train" anymore. The only thing moving apart from the valve itself and the cam lobe, is the single lifter. And those things are a marvel of fine precision. Hardened steel, yet they float on a cushion of oil, moving with the lightest touch. Have heard of Dealers not even bothering to check the valves because adjustment usually is not needed. To perform the adjustment you use a micrometer to measure the shim thickness and calculate the replacement size needed. Once the valve cover is off, checking is fairly simple using thickness "feeler" gauges for intake and exhaust. Plus they can be checked with the engine"cold" which makes it even simpler. As previously mentioned, with the engine running, if you listen next to the valve cover, you should hear a light ticking. Not silence. Not loud clacking. If I understand correctly, the newer engines just use a solid lifter without the shim, so it seems Toyota recognized adjustment is seldom required.

Valve clearance is measured COLD. The reason being IF any adjustments are needed, the cool off that would occur during shim exchange would require re-warming the engine to get an accurate clearance re-check.

Listen for valve train silence, clicking, or clacking is useless. Some engines have very aggressive opening ramps which promote "clicking." Also, it is easy for the inexperienced ear to mistake valves clicking from injector clicking.

Bucket cam followers come in three designs:

1) Bucket with selective thickness shim interposed the cam and bucket. (most common) 2) Bucket with selective thickness shim interposed the bucket and valve stem. 3) Bucket itself has a selective thickness head. In this design, the entire bucket is exchanged. (Standard Corolla engine from 1998 on is this way). This design is also the lightest weight which promotes higher rpm before valve float occurs.

--
- Philip @ Maximum Torque RPM